Show all abstracts
View Session
- Front Matter: Volume 7135
- Photonic Integration I
- Nano Photonics I
- Wide Bandgap Semiconductor Devices I
- Novel Active Devices I
- Best Student Papers
- Novel Active Devices II
- Photonic Integration II
- Nano Photonics II
- Nonlinear Photonics
- Novel Active Devices III
- Optical Switches and Modulators I
- Si Photonics
- Photonic Integration III
- Novel Active Devices IV
- Wide Bandgap Semiconductor Devices II
- Nano Photonics III
- Optical Switches and Modulators II
- Novel Active Devices V
- Fiber and Waveguide I
- Nanophotonics IV
- Fiber and Waveguide II
- Wide Bandgap Semiconductor Devices III
- Poster Session
Front Matter: Volume 7135
Front Matter: Volume 7135
Show abstract
This PDF file contains the front matter associated with SPIE
Proceedings Volume 7135, including the Title Page, Copyright
information, Table of Contents, and the Conference Committee listing.
Photonic Integration I
Hybrid integration for advanced photonic devices
Show abstract
Hybrid photonic integration with passive assembly techniques allows compact optical modules to be realised with high
optical performance and low packaging cost. Recent advances in integrating semiconductor optical amplifiers into
practical all-optical signal processing modules is described, with applications from optical memory to sophisticated
burst-mode optical regenerators.
Recent progress on arrayed-waveguide grating multi/demultiplexers based on silica planar lightwave circuits
Show abstract
This paper reports recent advances on arrayed waveguide grating (AWG) multi/demultiplexers based on silica-based
planar lightwave circuits (PLC). After briefly summarizing the fabrication and properties of PLCs, this work describes a
Mach-Zehnder interferometer (MZI)-synchronized AWG with reagrd to reduced loss, and athermalization. The paper
then reports our recent demonstration of the integration of a PLC-based wavelength selective switch (WSS) and an
integrated single-chip VMUX/DEMUX.
Progress with the uncooled electroabsorption modulator integrated DFB laser
Show abstract
We have developed the uncooled electroabsorption modulator integrated distributed feedback (EA/DFB) lasers for small-footprint and low-power-consumption transceiver modulus. In this study, we used the temperature-tolerant InGaAlAs materials in EA modulator. We investigated the 10.7-Gbps, 40-km transmission performances over wide temperature range. The dynamic extinction ratio was 9.9 dB and 13.3 dB at the 10ºC and 85ºC. The modulated output power was more than +3.7 dBm even at 85ºC. The long-term reliability was also investigated under APC condition at ambient temperature of 85ºC with starting current of 120 mA. There was no significant degradation of the operation current up to 5000 hours. Uncooled 1300-nm range 25-Gbps and 43-Gbps EA/DFB lasers were also investigated. These devices will provide cost-effective 100-Gbps and 40-Gbps transceiver for next-generation high speed network system. A wide temperature ranged 12-km transmission with over 9.6-dB dynamic extinction ratio was demonstrated under 25-Gbps modulation. A 43-Gbps 10-km transmission was also demonstrated. The laser achieved clearly opened eye diagrams with dynamic extinction ratio of over 7-dB from 25ºC to 85ºC.
Nano Photonics I
Mode behavior in triangle and square microcavities
Show abstract
Directional emission semiconductor microcavity lasers integrated with semiconductor planar technique are potential light
sources for photonic integrated circuits. In this article, we investigate mode characteristics for equilateral triangle and
square microcavities for realizing directional emission microcavity lasers. The analytical mode field distributions and
mode wavelengths are presented for two-dimensional (2D) triangle and square resonators, and directional emission are
simulated by finite-difference time-domain (FDTD) technique. The numerical results of mode Q-factors and output
coupling efficiencies for the triangle and square resonators show that high efficiency directional emission microcavity
lasers can be realized by directly connected an output waveguide to the resonators, because the mode field patterns are
standing distributions in the triangle and square resonator. Laser output spectra of fabricated InGaAsP/InP triangle lasers
are compared with the analytical results.
All-optical integrated multiplexer/demultiplexer and add-drop multiplexer using array of ring resonators for passive optical network
Show abstract
An integrated, compact and upgradeable bidirectional multiplexer/demultiplexer and Add-drop multiplexing based on
array of ring resonators is proposed. The proposed structure is realized using basic elements in optical integrated circuit
domain. We show that using the proposed block wavelength separation in dense wavelength division multiplexing
standard is possible. Also, the introduced basic block can be used to realize other elements in all-optical networks.
Dependence of the photoluminescence from silicon nanostructures on the size of silicon nanoparticles
Show abstract
The size dependence of photoluminescence (PL) from nanostructure semiconductors is examined. Considering the dependence of PL on both the silicon nanoparticles (Si NPs) sizes and their dispersion, we incorporated quantum confinement effects along with the effects of localized surface states to obtain an analytical expression for the PL spectra of silicon nanostructures. In order to obtain an insight into the effects of various parameters influencing the PL spectral profile in silicon nanostructures, we computed the PL spectra using relevant numbers in the expression. The computer-simulated results show (i) a marked deviation of PL spectrum from the normal distribution at higher energies due to the increase in oscillator strength with the decreasing mean Si NP size, (ii) The peak position redshifts and the peak intensity reduces with an increase in the standard deviation, and (iii) the luminescence peak blueshifts as the mean Si NP size decreases. To test our model, the Si NPs embedded in silicon nitride films were prepared by helicon wave plasma-enhanced chemical vapor deposition (HWP-CVD) technique using the H2 diluted SiH4 and N2 as reactant gas sources. The simulated PL spectra fit the experimental one rather nicely. And our results can explain the reported experimental observations on the luminescence from Si NPs.
Quantum-dot coupled tensile-strain quantum-well polarization insensitive semiconductor optical amplifier
Show abstract
The optical gain of quantum-dot (QD) semiconductor optical amplifier (SOA) is usually seriously dependent on
polarization, we propose QD coupled to tensile-strained quantum-well (QW) structure to obtain polarization
insensitive QD SOA. A polarization-dependent coupled carrier rate equation model and multi-section SOA
model are used to study the performance of QD-coupled QW SOA. Gain dependence on polarization is studied,
TE gain contribution by QWs and QDs is compared, and carrier distribution competition among QWs and QDs
is analyzed. It is shown that polarization insensitive gain can be realized in a relatively wide range of
wavelength if QD-coupled tensile-strained QW SOA is properly designed.
Wide Bandgap Semiconductor Devices I
Design and characterization issues in GaN-based light emitting diodes
Show abstract
The improvements in efficiency and reliability are essential to realize high performance light emitting diodes (LEDs). Uniform current spreading is very important to enhance both efficiency and reliability simultaneously. 3-dimensional circuit modeling and analysis method was developed in order to figure out influences of current crowding on performances. The method was applied to the top-surface emitting-type LEDs of 320 320 μm2 size. It was found that the current crowding was closely related to the improvements in series resistance, saturation of light output power, leakage current with operational time, and endurance of electrostatic discharge (ESD). Defects due to high ESD stress were observed at current crowding area. In order to suppress the peak electric field and enhance the ESD voltage, the floating metal was inserted near the n-electrode. About 4 times larger ESD voltages were experimentally measured at LEDs with floating metal structure compared to without one. A LED with the lozenge shape is fabricated to enhance light extraction efficiency over conventional design, i.e., rectangular parallel piped chip. A lozenge shaped LED has an additional advantage of easy chip making since it has natural crystallographic cleavage planes. About 11% larger light extraction efficiency was experimentally obtained in the lozenge shaped LEDs than conventional rectangular chips.
Reactive ion etching of ZnO using the H2/CH4 and H2/CH4/Ar mixtures
Show abstract
This work investigates the reactive ions etching (RIE) physical properties of n-type ZnO using H2/CH4 and H2/CH4/Ar
mixtures by varying the gas flow ratio, the radio-frequency (rf) plasma power and the chamber pressure. Atomic force
microscopy (AFM) results and surface topographies are discussed. Although the etching rate of the n-ZnO at an H2/CH4
flow rate of 100/0 sccm, a work pressure of 100 mTorr and an rf power of 300 W is lower than under any other
conditions, the rms roughness of 43.78 nm is the highest, and supports the application of roughened transparent contact
layer (TCL) in light-emitting diodes (LEDs). The dynamics associated with the high etching rate were highly efficient at
an H2/CH4/Ar flow rate of 38/5/57 sccm, a work pressure of 150 mTorr and an rf power of 300 W. In addition, the ZnO
with thermal annealing were studied. The slower etching rate of annealed n-ZnO is observed due to an increase the
crystal quality of the ZnO films after thermal annealing which consists with the x-ray diffraction (XRD) results.
Receiving method of maritime light wireless communication based on LED beacons
Show abstract
LEDs (light emitting diodes) can be applied in both illumination and communication. A system of maritime
wireless communication with ships based on LED beacons is proposed in this paper. The communication space model
and optical transmission model were set up, visible wireless communication manner was analyzed. An anti-fading
method combining space and time diversity is adopted due to quick signal attenuation and large noise from nature light
interference. After filtering and judgment, the received diversity signals are separated to do bit comparison using
Hamming Perception Network. Through analysis and simulation, compared to ordinary space diversity or time diversity
way, this kind of anti-fading method can increase reliable communication distance greatly, reduce equipment cost and
improve bandwidth utilization rate.
Analysis of the transmission spectra and the parameters extraction of the GaN-based films
Show abstract
Nowadays, GaN-based multi-layer materials is developing fast, and it is important to know their
interface and optical properties for devices design and fabrication. In this letter, the transmission
spectra are analyzed, and the dependence of the transmission spectra on parameters of the samples is
discussed. Sequentially, we obtain the transmission spectra of a series of GaN-based samples.
Simulation of the transmission spectra is done and useful information is extracted. For one of our
samples, the refractive index varies a little between 2.518 and 2.305 with the wavelength from 400 to
800nm, while the extinction coefficient is 6x-10-9.5exp(2700/λ), and the thickness is 2860nm. Finally,
we get the dispersion relationship of the GaN and AlGaN films, and it is compared with the results of
some other research groups.
The effect of wet chemical etching by KOH solution to the contact on the solar-blind Al0.65Ga0.35N material
Show abstract
Recently, high-Al-content AlGaN alloy systems have attracted increasing attention, and it is urgent and
important to achieve excellent Ohmic contacts with low specific contact resistivity, good thermally stability, clear
borderline and smooth surface morphology of this alloy systems to optimize the performance of photoelectric
devices. In the experiment, we found that surface disordered layer and oxides including native oxide could be
removed by boiling KOH solution. The surface status of both samples was evaluated with scanning electron
microscope (SEM) and X-ray photoelectron spectra (XPS). For comparison, then A Ti/Al/Ti/Au multilayer was
deposited on the samples with and without wet chemical etching to observe their electric properties. After annealing,
I-Vcharacteristics via Keyley236 electric analyzer was measured. Ohmic contacts with the contact specific resistivity
of 6.55×10-4Ωcm2 were obtained between treated samples and the multi-metals. However, nonlinear I-V curves
indicated that the contact on the untreated sample was still the Schottky contact.
Growth of AlN single crystals by modified PVT
Show abstract
Growth of AlN single crystals is achieved by physical vapor transport (PVT) in the reverse cone tungsten crucible, which
is induction-heated, for obtaining proper sublimation rate and ensuring effective heat and mass transport. In the
experiment, there is a little hole at the center of crucible lid where the temperature is lower than the periphery, and there
is a tungsten cover on the lid. A self-seeded AlN single crystal is grown due to the anisotropic growth property of AlN
crystals and limitation of the hole. During the following growth, the crystal as a seed becomes a large size and high
quality single crystal. By modified PVT, separate AlN single crystals with diameters of larger than 2mm on the crucible
lid have been obtained successfully for the first time.
Novel Active Devices I
VCSELs: their 30 years history and new challenges
Show abstract
We could have the 30-year anniversary since a VCSEL was invented by Kenichi Iga. We have seen various
applications including datacom, sensors, optical interconnects, spectroscopy, optical storages, printers, laser
displays, laser radar, atomic clock, optical signal processing and so on. A lot of unique features have been shown,
low power consumption, a wafer level testing and so on. In this paper, the brief history and our recent research
activities on VCSEL photonics will be reviewed. We present the wavelength engineering of VCSEL arrays for
use in high speed short-reach systems, which includes the wavelength integration and wavelength control. The
joint research project on ultra-parallel optical links based on VCSEL technologies will be introduced for high
speed LANs of 100Gbps or higher. The small footprint of VCSELs allows us to form a densely packed VCSEL
array both in space and in wavelength. The wavelength engineering of VCSELs may open up ultra-high capacity
networking. Highly controlled multi-wavelength VCSEL array and novel multi-wavelength combiners are
developed toward Tera-bit/s-class ultrahigh capacity parallel optical links. In addition, the MEMS-based VCSEL
technology enables widely tunable operations. We demonstrated an "athermal VCSEL" with avoiding temperature
controllers for uncooled WDM applications. In addition, new functions on VCSELs for optical signal processing
are addressed. We present an optical nonlinear phase shifter based on a VCSEL saturable absorber.
Also, highly reflective periodic mirrors commonly used in VCSELs enables us to manipulate the speed of light.
This new scheme provides us ultra-compact intensity modulators, optical switches and so on for VCSEL-based
photonic integration. Also, this paper explores plasmonic VCSELs.
Growth of BxGa1-xAs, BxAl1-xAs and BxGa1-x-yInyAs epilayers on (001)GaAs by LP-MOCVD
Show abstract
High quality zinc-blende BxGa1-xAs, BxAl1-xAs, BxGa1-x-yInyAs epilayers and relevant MQW structures containing 10-
period BGaAs(10nm)/GaAs(50nm) and BGaInAs(10nm)/GaAs(50nm) have been successfully grown on exactly-oriented
(001)GaAs substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). Triethylboron,
trimethylgallium, trimethylaluminium, trimethylindium and arsine were used as the precursors. Boron incorporation
behaviors have been studied as a function of growth temperature and gas-phase triethylboron mole fraction. In this study,
the maximum boron composition x of 5.8% and 1.3% was achieved at the same growth temperature of 580°C for bulk
BxGa1-xAs and BxAl1-xAs, respectively. 11K photoluminescence (PL) peak wavelength of lattice-matched BxGa1-x-yInyAs
epilayer with boron composition of about 4% reached 1.24μm.
Numerical study of multi-longitudinal-mode dynamics of semiconductor ring lasers subject to ultra-short optical pulse injection
Show abstract
A novel multi-mode model suitable for semiconductor ring lasers with ultra short optical pulse injection including all nonlinear coupling components is established and used to explore multilongitudinal-mode dynamics. Faster switching off time is predicated.
Microfluidic photonic integrated circuits
Show abstract
We report on the development of an inexpensive, portable lab-on-a-chip flow cytometer system in which microfluidics,
photonics, and acoustics are integrated together to work synergistically. The system relies on fluid-filled twodimensional
on-chip photonic components such as lenses, apertures, and slab waveguides to allow for illumination laser
beam shaping, light scattering and fluorescence signal detection. Both scattered and fluorescent lights are detected by
photodetectors after being collected and guided by the on-chip optics components (e.g. lenses and waveguides). The
detected light signal is imported and amplified in real time and triggers the piezoelectric actuator so that the targeted
samples are directed into desired reservoir for subsequent advanced analysis. The real-time, closed-loop control system
is developed with field-programmable-gate-array (FPGA) implementation. The system enables high-throughput (1-
10kHz operation), high reliability and low-powered (<1mW) fluorescence activated cell sorting (FACS) on a chip. The
microfabricated flow cytometer can potentially be used as a portable, inexpensive point-of-care device in resource poor
environments.
808nm high-power high-efficiency GaAsP/GaInP laser bars
Show abstract
808nm high power diode lasers, which is rapidly maturing technology technically and commercially since the
introduction in 1999 of complete kilowatt-scale diode laser systems, have important applications in the fields of industry
and pumping solid-state lasers (DPSSL). High power and high power conversion efficiency are extremely important in
diode lasers, and they could lead to new applications where space, weight and electrical power are critical. High
efficiency devices generate less waste heat, which means less strain on the cooling system and more tolerance to thermal
conductivity variation, a lower junction temperature and longer lifetimes. Diode lasers with Al-free materials have
superior power conversion efficiency compared with conventional AlGaAs/GaAs devices because of their lower
differential series resistance and higher thermal conductivity. 808nm GaAsP/GaInP broad-waveguide emitting diode
laser bars with 1mm cavity length have been fabricated. The peak power can reach to 100.9W at 106.5A at quasicontinuous
wave operation (200μs, 1000Hz). The maximum power conversion efficiency is 57.38%. Based on these high
power laser bars, we fabricate a 1x3 arrays, the maximum power is 64.3W in continuous wave mode when the current is
25.0A. And the threshold current is 5.9A, the slope efficiency is 3.37 W/A.
Optical feedback assistant current-driven polarization switching of VCSELs
Show abstract
This research investigated the effects of optical feedback on the current-driven polarization switching (CDPS) of
VCSELs which exhibit significant polarization-switching hysteresis loop in L-I curve. Experimental results indicated
that optical feedback can increase the bandwidth of CDPS. For VCSELs which exhibit wide polarization-switching
hysteresis loop, the extension of CDPS bandwidth is limited by the time required to modulate the current to cross the
width of the hysteresis loop. Accordingly, the optical feedback configuration which results the narrowest hysteresis loop
will conduct the largest bandwidth extension.
Best Student Papers
A six-port circulator based on multimode interference
Show abstract
As a key nonreciprocal device, the optical circulator builds optical links to several terminals in a circulating manner. The waveguide-type circulator with port count more than four has not been discussed, mainly due to the strict phase matching and adjustment. In this paper, a six-port optical circulator is proposed by introducing the nonreciprocal phase shifts (NPS) into a 3×3 multimode interference coupler. The structure with Ce:YIG material bonded to SOI waveguide is employed to illustrate the implementation and do the device simulation. There is no complex phase matching in the whole design. Good performance can be expected with the present fabrication techniques. This design scheme can also be easily generalized to the circulators with even more terminals.
Concentric silicon micro-ring resonators with enhanced transmission notch depth
Show abstract
In this work, we have analyzed, fabricated and demonstrated concentric micro-ring resonators in silicon-on-insulator (SOI) structure for enhanced transmission notches. The operation principles of the concentric ring resonators are studied by time-domain coupled-mode theory. Directional coupling between concentric rings offers another freedom in designing deep notch optical filters and ultra-sensitive biosensors. The finite-difference-time-domain (FDTD) simulations have shown the improvement of the notch depth, evenly distributed mode field and the effect of the resonance shift. The device is demonstrated in silicon-on-insulator structure. Transmission notch depth improvement of ~ 15dB is demonstrated for the 21-20.02-μm-radius double-ring structure comparing with the single 21-μm-radius ring.
Study of active width-reduced line-defect photonic crystal waveguides for high speed applications
Show abstract
We study the electrical and optical characteristic of the width-reduced line-defect photonic crystal waveguides with lateral p-i-n structures on Silicon-on-Insulator substrates. A longitudinal-section-based electrical model is built to take the holes into consideration. Compared with the classical line-defect photonic crystal waveguides, the width reduced photonic crystal waveguide has much stronger capacity in optical confinement in plane, which can allow a narrower intrinsic layer that leads to a fast electric response.
Design and fabrication of visible/mid-infrared dual-band microfilter array
Show abstract
Integrated visible/infrared dual-band filter array is the key component of compact, lightweight, rigid miniature dual-band
CCD sensing system. Interference cut-off filter array and interference absorbing filter array have been designed for
infrared and visible pass band respectively. A simple, effective and compatible with high temperature deposition process
lift-off technique for striping thick infrared film was investigated. Integrating photolithography, ion beam assisted
electron beam physical vapor deposition and improved lift-off process, dual-band microfilter array with good
performance was fabricated on the same sapphire substrate consecutively. Details of design and fabricating procedure are
elucidated, and experimental results are presented.
Phase shift of plasmons excited by slits in a metal film illuminated by oblique incident TM plane wave
Show abstract
The interactions between the optical light and sub-wavelength structures in metal film have sparked great interest on surface plasmon polaritons (SPPs). One effective way to interpret these phenomena is to make use of the phase shift between the SPP excited and the incident wave. Many theoretical and experimental studies have shown that this shift approximate to π is intrinsic at normal incidence. In this paper, the phase shift at oblique incidence is analyzed and used to interpret the transmission effect for the first time to our knowledge. A simplified 2D scattering formulation using vector finite element method is set up. Simulations show the phase shift can be approximate to π over a large range of incidence angles. With this shift, the conditions for the enhanced or suppressed transmission and the corresponding destructive or constructive interference of SPPs at oblique incidence are achieved. The transmission effect for incidence angle not satisfying these conditions, as well as its potential applications is also discussed.
The structural and optical properties of high-Al-content AlInGaN epilayers grown by RF-MBE
Show abstract
AlInGaN Quaternary Alloys were successfully grown on sapphire substrate by radio-frequency plasma-excited
molecular beam epitaxy (RF-MBE). Different Al content AlInGaN quaternary alloys were acquired by changing the Al
cell's temperature. The streaky RHEED pattern observed during AlInGaN growth showed the layer-by-layer growth
mode. Rutherford back-scattering spectrometry (RBS), X-Ray diffraction (XRD) and Cathodoluminescence (CL) were
used to characterize the structural and optical properties of the AlInGaN alloys. The experimental results show that the
AlInGaN with appropriate Al cell's temperature, could acquire Al/In ratio near 4.7, then could acquire better crystal and
optical quality. The samllest X-ray and CL full-width at half-maximum (FWHM) of the AlInGaN are 5arcmin and 25nm,
respectivly. There are some cracks and V-defects occur in high-Al/In-ratio AlInGaN alloys. In the CL image, the cracks
and V-defect regions are the emission-enhanced regions. The emission enhancement of the cracked and V-defect regions
may be related to the In-segregation.
Novel Active Devices II
Ultra-wide temperature range operation of DFB lasers at 1310 nm and 1490 nm
Show abstract
Un-cooled single mode operation of 1310 nm and 1490 nm DFB (distributed feedback) lasers across a wide temperature span of 180 °C and 170 °C has been demonstrated. The lasers showed excellent performances such as high output power and high modulation bandwidth as well. This makes them ideal candidates for G-PON (Giga bit rate passive optical network) application as key components for ONU (optical network unit) and OLT (optical line terminal).
Highly efficient diode pumped solid state lasers using mixed vanadate crystals Nd:YxGd1-xVO4 for laser communications
Show abstract
We present, for the first time, comparative studies of laser performance in the mixed vanadate crystals
Nd:YxGd1-xVO4 with direct and indirect pumping. The resulting highly efficient miniaturized laser has potential for laser
communications.
Ultrafast all-optical switching using intersubband transitions in InGaAs/AlAs/AlAsSb quantum wells
Show abstract
Ultrafast all-optical switch based on intersubband transitions in InGaAs/AlAs/AlAsSb quantum well is described.
Because of very fast intra-band relaxation in conduction band, we can obtain very fast response of around 1ps. The
operation principles and characteristics as an absorption saturation type device are described. Also described is the
operation as an all-optical phase modulator. With Mach-Zehnder interferometer configuration, error free all-optical
demultiplexing operation from 160-Gb/s to 40-Gb/s was achieved.
A strained InGaAs/InAlAs coupled quantum well with polarization-independent large positive electro-refractive index change
Show abstract
By analyzing the ground eigenstates of an InGaAs/InAlAs symmetric coupled quantum well for zero applied electric field and their changes along with an applied electric field, we find its advantages and disadvantages when it is applied to optical switching device. Hence a novel coupled quantum well structure is put forward. To obtain polarization independence, a tensile strain is applied to the quantum well layer. In the case of low applied electric field (F=15 kV/cm) and low absorption loss (for TE mode, α=55.56cm-1; for TM mode, α=75.58cm-1), a polarization-independent large electric-field-induced refractive index change (for TE mode, Δn=0.0108; for TM mode, Δn=0.0107) is obtained in the optimized InGaAs/InAlAs coupled quantum well structure at operating wavelength (λ1550nm). The large refractive index change obtained with the optimized InGaAs/InAlAs coupled quantum well under so low absorption loss and applied electric field is very attractive for the semiconductor optical switch device. This manifests the optimized coupled quantum well structure has a great potential for application to ultra-fast and low-voltage optical switches and traveling wave modulators.
Photonic Integration II
Research on photonic components: the perspective of the European Commission
Show abstract
The importance of photonic technologies for the European economy is recognized by the European Union and enjoys
continued support. The mechanisms of the European Union to support research and development by introducing the "7th
European Framework Program for Collaborative Research" are outlined. The topical content of the Framework Program
is presented, as well as its implementation and in particular the support of photonic components related research and
development. We will highlight the importance of the collaborative European effort and give examples of its impact. We
will then provide an overview of the current topics supported by the European Commission. We will conclude by
presenting the long term vision and giving indications on the likely research priorities for Photonic Components in the
ICT Workprogram 2009-2010 of the 7th Framework Program (FP7).
Nano Photonics II
Preparation and transmission loss of the nano-crystal and polymer composite Bi4Ti3O12/PEK-c films
Show abstract
Bismuth titanate, Bi4Ti3O12 (BTO), is a typical ferroelectric material with useful properties for optical memory,
piezoelectric and electro-optic devices. Its nano-crystals were compounded by the chemical solution decomposition
(CSD) technique. The structure and size of BTO were analyzed by X-ray diffraction (XRD) and transmissive electron
microscopy (TEM). Three sorts of composite films BTO/PEK-c with different BTO concentration were prepared by
spin-coating method at certain conditions. In this article, the scattering losses in thin films were obtained using the
photographic technique. The losses in the films with different BTO weight ratios were compared and analyzed.
Porous silicon-based photonic crystals optical devices for polarization band-pass filtering and sensing applications
Show abstract
We report on the design of porous silicon based polarization band-pass filters, which is not only have excellent optical properties with p-polarization transmittance and s-polarization reflectance in the NIR field, but also can be used for excellent biosensor and gas sensing applications.
Nonlinear Photonics
Nonlinear optical and near-infrared luminescence properties of Nd3+-doped heavy metal silicate glasses
Show abstract
The glass samples of SiO2-Al2O3-CdO-Li2O-K2O-Na2O with different Nd3+-doped concentration are prepared by high-temperature
solid-state reaction method, and test the absorption spectrums as well as emission spectrum excited at 488
nm, 532 nm and 808 nm. The third-order optical nonlinear properties of glasses samples are investigated by the z-scan
technique. With the increment of doping concentration of Nd3+, the third-order nonlinear refractive index and the
absorption index increase, so it belongs to the self-focusing and reverse saturated absorption medium. The glass samples
open a outlook of application for nonlinear optical medium and excellent luminescence materials.
The research of properties of Eu3+-doped cadmium aluminium silicate glass
Show abstract
We have prepared (40SiO2-14Al2O3-(40-x) CdO-2Li2O-2K2O-2Na2O -x Eu2O3) cadmium aluminium silicate glasses
doped with europium by high temperature solid-state reaction method. The absorption spectra, excitation spectra,
emission spectra are obtained. With the increase of Eu2O3, the absorption peaks are founded increasing to the best doped
concentration and then reducing, which is nonlinear relationship. The charge-transfer band is moved to 320 nm due to
the addition of Cd2+. We can see that the ratio of peak in 591 nm and 615 nm is 0.6-0.75 in general, and is unrelated to
doped concentration. By changing concentration of Eu3+.We can adjust and mix different intensity of light according to
the demand.
Nonlinear phenomena analysis of tunable external cavity semiconductor laser with sampled fiber grating
Show abstract
The theoretical model considering nonlinear effects in the external cavity semiconductor laser with sampled fiber grating
has been presented. Such effects are including the asymmetric side mode suppression ratio (SMSR) or power
characteristics, and hysteresis phenomena. This theoretical model is based on the transmission line theory on compound
cavity. The parameters of the laser, e.g. active section length and phase section length, have been optimized to suppress
such nonlinear effects, which makes the device control simple and reliable, while the performances such as 16nm tuning
range, 40dB SMSR, 8.5mW output power can be maintained.
LD-pumped all-solid-state yellow laser based on frequency-doubled self-Raman laser
Show abstract
LD-pumped all-solid-state yellow laser based on frequency-doubled Nd:YVO4 crystal self-Raman laser was demonstrated. Through extracavity frequency-doubling with KTP crystal, the maximum average output power of the yellow laser was measured to be 495 mW with the incident pump power of 18 W. The corresponding optical conversion efficiency was about 2.75 %. The highest pulse energy, the shortest pulse width and the highest peak power of the yellow laser were obtained to be 19.9 μJ, 4.5 ns and 3.88 kW, respectively.
Second harmonic generation in periodically poled lithium niobate waveguide using femtosecond laser pulses
Show abstract
We present in this paper the fabrication and characterization of thermally stable double line waveguides in Z-cut periodically poled Lithium Niobate crystals. The waveguides were fabricated by using a femto-second laser, and utilized for second-harmonic generation. Our experiments have shown that a quasi-phase matching wavelength of 1548.2 nm, a tuning bandwidth of 2 nm, and a tuning temperature range of 150.4±1.6°C can be achieved.
Nonlinear optical properties of Ho3+-doped borosilicate glass
Show abstract
Using an improved borosilicate glass with small third-order optical nonlinearities, i.e., nonlinear refractive index (NLRI)
and nonlinear absorption coefficient (NLAC), as the matrix and comparative glass, two types of Ho3+-doped glass are
prepared with a solid-phase smelting process at a relatively low temperature, and their third-order optical nonlinearities
are measured by the closed-aperture Z-scan technique using nanosecond laser pulses at 532nm wavelength. It is found
that the matrix glass possesses a positive third-order NLRI and a positive third-order NLAC, and both the third-order
NLRI and NLAC of Ho3+-doped glasses are one order larger than those of the matrix glass, respectively. Also, an open-aperture
Z-scan experiment and an optical limiting experiment further demonstrate that the Ho3+-doped glasses have a
high third-order NLAC. All the experimental results show that this Ho3+-doped glasses have good protection
performance for the 532nm-laser.
Novel Active Devices III
Single dye molecule laser via energy transfer mechanism
Show abstract
Motivated by the recent progresses in one-atom laser and single-molecule manipulation, this work presents the model and simulations of a single dye molecule laser device, which consists of a single dye molecule as an acceptor in a microcavity pumped by multiple donors via the intermolecular resonance energy transfer mechanism. The photon intensity is calculated at the emission peaks of donor and acceptor dyes for different pump rates and donor numbers. Finally, it is demonstrated that stimulated emission gains a distinct advantage over spontaneous emission under appropriate conditions. This work would have many important applications in a wide range of fields from physics and chemistry to nanotechnology in future.
A novel bottom-emitting VCSEL's one-dimension array
Show abstract
A novel 980nm bottom-emitting VCSELs array with high power density and good beam property of Gaussian far-field
distribution is reported. This array is composed of 5 symmetrically-arranged elements of 200&μm,150μm and
100μm-diameterμwith the center spacings of 300μm and 250μm respectively. The maximum power is 880mW at a
current of 4A, corresponding to 1KW/cm2 average optical power density. The differential resistance is Ω with a
threshold of 0.56A. The novel array is compared with a 300μm-aperture-size single device and a 4*4 2-D array with
50μm element aperture size and 250μm centre spacing. The three devices have the same lasing area. The conclusion is
that the novel array is better in the property of output power, threshold current, lasing spectra, far-field distribution etc.
Optical Switches and Modulators I
Transformation optics and invisibility cloaks
Show abstract
In this paper, we briefly summarize the theory of transformation optics and introduce its application in achieving
perfect invisibility cloaking. In particular, we theoretically show how the task of realizing cylindrical invisibility
cloaks can be eased by using either structural approximation or material simplification. The corresponding
invisibility performances of the approximate or simplified cylindrical cloaks are presented in detail.
Linearization of periodic phase response for liquid crystal modulator
Show abstract
Liquid crystal modulator(LCM) is now widely applied, especially in optical telecommunication networks. However,
according to the electro-optic characteristic of liquid crystal, we will obtain nonlinear phase response when LCM is
driven by the voltage varying with time linearly(v=kt+v0). And in practical application this nonlinear phase response will
affect the modulation precision, communication modulation efficiency and so on. This paper presents a logarithm driving
signal model to linearize the nonlinear phase response of LCM between 0 and π. When driven by a periodic signal whose
voltage varies from 2.0 to 10.7V in the way of logarithm in every periods, the LCM's phase response hops in the point of
intersection of two voltage periods. Therefore, we advance another periodic logarithm driving signal, whose voltage
ascends from 2.0 to 10.7V in first half periods and descends from 10.7 to 2.0V in the other half periods. Furthermore, We
find that the degree of phase response linearization of LCM decreases with the frequency of driving signal increasing.
This paper proposes mapping the nonlinear phase response to linear one to overcome this problem. The experimental
results indicate that obtaining the linear phase response of liquid crystal between 0 and π with different-frequency driving
signals is feasible.
A novel wavelength switchable fiber ring laser
Show abstract
We demonstrate a fiber ring laser with a dispersion compensation fiber (DCF) and a delayed
interferometer (DI), which is able to switch eleven wavelengths one by one. In ring cavity,
DCF supplies different effective cavity lengths for different wavelengths, DI generates a
wavelength comb corresponding to the ITU grid, a flat-gain erbium-doped fiber amplifier
(EDFA) provides uniform gain for each lasting wavelength, and a semiconductor optical
amplifier (SOA) not only acts as active modulator, but also alleviates homogeneous
broadening effect of EDFA. Stable pulse trains with a pulsewidth about 40 ps at 10 GHz have
been obtained by injecting external optical control signals into the laser. Wavelength switching
process among eleven wavelengths is achieved by merely tuning an intracavity optical delay
line.
Compact optical modulator based on carrier induced gain of an InP/InGaAsP micro-disk cavity integrated on SOI
Show abstract
A compact electro-optic modulator on silicon-on-insulator is presented. The structure consists of a III-V microdisk cavity heterogeneously integrated on a silicon-on-insulator wire waveguide. By modulating the loss of the active layer included in the cavity through carrier injection, the power of the transmitted light at the resonant wavelength is modulated. ~10 dB extinction ratio and 2.73 Gbps dynamic operation are demonstrated without using any special driving techniques. The results are consistent with the theoretical simulations.
Reflection mechanism in the total-internal-reflection optical waveguide switch
Show abstract
The modal expansion method is utilized to study the reflection mechanism in the total-internal-reflection (TIR) switch. Due to the confinement of the waveguide, the beam reflection within the TIR switch is completely different from that in the free space. Its essence is the degeneracy between the even and odd modes in the waveguide of the reflection region.
Si Photonics
Integrated photonic beamformer employing continuously tunable ring resonator-based delays in CMOS-compatible LPCVD waveguide technology
Show abstract
In this paper a novel CW laser-compatible, squint-free, continuously tunable ring resonator-based optical beamformer
mechanism for a phased array receiver system is proposed and partly demonstrated. When the optical delay elements and
optical signal processing circuitry are integrated on a chip, a single-chip optical beam forming network (OBFN) is
obtained. The optical delay elements are ideally continuously tunable to achieve continuous control of the beam
direction, and should have a flat delay and magnitude response over the signal band, to avoid distortion. In the proposed
system architecture, filter-based optical single-sideband suppressed-carrier modulation and balanced coherent optical
detection are used. Such architecture has significant advantages over a straightforward architecture using optical
intensity modulation and direct optical detection, namely reduced complexity of the OBFN chip, and enhanced dynamic
range. Measurements on an actual 1×8 OBFN chip and an optical sideband filter chip are presented. Both are realized in
CMOS-compatible planar optical waveguide technology (TriPleX).
Terahertz wave dielectric properties of P-type silicon
Show abstract
We have measured the absorption spectrum of three kind resistivity p-type silicons by backward-wave oscillator
(BWO).The absorption spectrum is examined and analyzed by least square method. The refractive index, absorption
coefficient, and dielectric functions of various resistivity p-type silicons are obtained in the frequency range extending
from 0.23 THz to 0.375 THz. The experimental results indicate that the absorption coefficient of the p-type silicons are
decreased with the resistivity increase and its least absorption coefficient equals 3.87x10-4 cm-1. Our results demonstrate
that the applicability of the backward-wave oscillator THz absorption spectroscopy to p-type silicon characteristic
analysis by calculating the absorption spectra. This work establishes the basic spectra data for the various resistivity ptype
silicons are very significative to design the terahertz waveguide with low loss.
The effect of argon ion implantation and preanodization argon ion implantation on photoluminescence of porous silicon
Show abstract
Photoluminescence of Ar+ implanted porous silicon and porous structure of Ar+-implanted silicon (porous silicon by
preanodization ion implantation) at energy of middle-energy (30keV) are investigated to gain insight into the
photoluminescence properties and photoluminescence mechanism. The results show that the photoluminescence intensity
of Ar+ implanted porous silicon was reduced, which was attributed to the removal of surface oxygen and creation of
defects that act as nonradiative recombination; And whether samples were prepared by p-type or n-type silicon wafers,
the photoluminescence intensity of porous structure of Ar+-implanted silicon was enhanced that we attribute these to the
enhanced formation of porous silicon microstructure induced by ion implantation and oxygen-related defects were
increased.
100 mm integration of III-V and silicon-on-insulator wafers for the realization of distributed feedback silicon evanescent lasers
Show abstract
Abstract 100 mm wafer bonding of InP-based structure and silicon-on-insulator wafers is presented with the use of a lowtemperature
(300 °C) O2 plasma-assisted wafer bonding process. An efficient vertical outgassing channels (VOCs) design
is developed to eliminate the fundamental obstacle of interfacial voids in bonding due to intrinsic chemical reactions.
Generated gas species of H2O and H2 can quickly diffuse to VOCs, etched through-holes to buried oxide layer (BOX), and
absorbed by the BOX layer owing to the open network structure and large gas permeability. The interfacial void density is
reduced from 55,093 cm-2 down to 3 cm-2, more than five orders of magnitude reduction for appropriate design of VOCs.
Uniform patterning of VOCs leads to no outgassing "dead zone" across the entire bonding area, and decrease of the
thermal mismatch-induced interfacial strain potentially as well, which both result in the wafer scale-independent bonding.
In addition, we present distributed feedback silicon lasers realized on the hybrid silicon evanescent platform. The laser
operates continuous wave with a single mode output at 1600 nm. A continuous wave (CW) low threshold of 25 mA with a
maximum output power of 5.4 mW is demonstrated at 10 °C. The obtained side mode suppression ratio of 50 dB, 3.6
MHz linewidth, and over 100 nm single mode operation band are comparable to those of commercial III-V DFB devices.
These highly single mode lasers may find applications in computer interconnect.
Photonic Integration III
40 Gb/s InGaAlAs EML module based on identical epitaxial layer integration scheme
Show abstract
High-speed AlGaInAs multiple-quantum-well (MQW) electroabsorption modulated lasers (EMLs) based on identical epitaxial layer (IEL) integration scheme are developed for 40 Gb/s optical fiber communication systems. The electroabsorption modulator (EAM) section adopts a narrow high-mesa waveguide formed by inductively coupled plasma (ICP) dry etching technique, and a self-aligned planarization technique is employed to further reduce the device capacitance. Resonances are observed in the small signal modulation response of the packaged EML module, which are attributed to parallel-plate modes of the coplanar waveguide (CPW) transmission line used for modulation signal feeding and the residual reflection at the modulator facet, respectively. The influence of such resonances on the large signal eyediagram performance of the device is studied, and methods for their suppression are presented. Clear eye opening under 40 Gb/s non-return-to-zero (NRZ) modulation has been demonstrated for the optimized EML module.
InP-based monolithically integrated 1310/1550nm diplexer/triplexer
Show abstract
Multiple streams of high definition television (HDTV) and improved home-working infrastructure are currently driving
forces for potential fiber to the home (FTTH) customers [1]. There is an interest to reduce the cost and physical size of
the FTTH equipment. The current fabrication methods have reached a cost minimum. We have addressed the costchallenge
by developing 1310/(1490)/1550nm bidirectional diplexers, by monolithic seamless integration of lasers,
photodiodes and wavelength division multiplexing (WDM) couplers into one single InP-based device. A 250nm wide
optical gain profile covers the spectrum from 1310 to 1550nm and is the principal building block. The device fabrication
is basically based on the established configuration of using split-contacts on continuos waveguides. Optical and electrical
cross-talks are further addressed by using a Y-configuration to physically separate the components from each other and
avoid inline configurations such as when the incoming signal travels through the laser component or vice versa. By the
eliminated butt-joint interfaces which can reflect light between components or be a current leakage path and by leaving
optically absorbing (unpumped active) material to surround the components to absorb spontaneous emission and nonintentional
reflections the devices are optically and electrically isolated from each other. Ridge waveguides (RWG) form
the waveguides and which also maintain the absorbing material between them. The WDM functionality is designed for a
large optical bandwidth complying with the wide spectral range in FTTH applications and also reducing the polarization
dependence of the WDM-coupler. Lasing is achieved by forming facet-free, λ/4-shifted, DFB (distributed feedback
laser) lasers emitting directly into the waveguide. The photodiodes are waveguide photo-diodes (WGPD). Our seamless
technology is also able to array the single channel diplexers to 4 to 12 channel diplexer arrays with 250μm fiber port
waveguide spacing to comply with fiber optic ribbons. This is an important feature in central office applications were
small physical space is important.
Novel Active Devices IV
AlGaInAs quantum-well saturable absorbers for a diode-pumped passively Q-switched Nd:YVO4 laser at 1064 nm
Show abstract
We report the use of AlGaInAs quantum wells (QWs) as a saturable absorber in the
Q-switching of a high-power diode-pumped Nd-doped 1064nm laser. The barrier layers are
designed to locate the QW groups in the region of the nodes of the lasing standing wave for
avoiding damage. With an incident pump power of 22 W at 878nm, an average output power of
6.8 W with a Q-switched pulse width of 0.85 ns at a pulse repetition rate of 105kHz was obtained.
Twin-contact high brightness tapered laser for high modulation efficiency high speed signal modulation
Show abstract
We report a compact transmitter with 0.4 W output optical modulation amplitude at 1 Gb/s using a twin-contact directly
modulated laser with a ~100 mA applied current swing and a 2 A constant bias current. Bit-error-ratio measurements
confirm high signal quality for optical wireless communication applications.
Wide Bandgap Semiconductor Devices II
A blue-violet enhanced BDJ photodetector and its application in the color measurement of RGB LEDs for solid-state lighting
Show abstract
A blue-violet enhanced BDJ photodetector which can simultaneously determine the centroid wavelength and the
radiant power of LEDs from 380 to780nm was investigated, and its application in the color measurement and the white
balancing of RGB white LEDs was demonstrated. This BDJ photodetector directly gave the chromatic coordinates of a
LED that was approximated as a monochromatic stimulus due to its narrow spectrum compared with the CIE colormatching
functions. Maximal simulated and experimental errors Δ'u'v' to the target white point of the white balanced
RGB LEDs was 0.0154 and 0.0214. The BDJ photodetector also performed to be sensitive to the spectrum variation
characterized by CCT, and was preferable as a sensor for monitoring the white point.
Strain relaxation characteristics of a single InGaN-based nanopillar fabricated by focused ion beam milling
Show abstract
A free-standing nanopillar with a diameter of 300 nm, and a height of 2 μm is successfully demonstrated by focused ion
beam milling. The measured micro-photoluminescence (μ-PL) from the embedded InGaN/GaN multiple quantum wells
shows a blue shift of 68 meV in energy with a broadened full-width at half maximum, ~200meV. Calculations based on
the valence force field method suggest that the spatial variation of the strain tensors in the nanopillar results in the
observed energy shift and spectrum broadening. Moreover, the power-dependent µ-PL measurement confirms that the
strain-relaxed emission region of the nanopillar exhibits a higher radiative recombination rate than that of the as-grown
structure, indicating great potential for realizing high-efficiency nano devices in the UV/blue wavelength range.
Epitaxial Lateral Overgrowth of GaN-based Light Emitting Diodes on SiO2 Nanorod-Array Patterned Sapphire Substrates by MOCVD
Show abstract
High efficiency GaN-based light-emitting diodes (LEDs) are demonstrated by a nanoscale epitaxial lateral
overgrowth (NELO) method on a SiO2 nanorod-array patterned sapphire substrate (NAPSS). The SiO2 NAPSS was
fabricated by a self-assembled Ni nano clusters and reactive ion etching. The average diameter and density of the formed
SiO2 nanorod-array was about 100 to 150 nm and 3 x 109 cm-2. The transmission electron microscopy images suggest
that the voids between SiO2 nanorods and the stacking faults introduced during the NELO of GaN can effectively
suppress the threading dislocation density. The output power and external quantum efficiency of the fabricated LED by
NELO method on NAPSS were enhanced by 52% and 56% respectively, compared to those of a conventional LED. The
improvements originated from both the enhanced light extraction assisted by the NAPSS, and the reduced dislocation
densities using the NELO method.
Nano Photonics III
Multiwavelength quantum-dot semiconductor fiber ring laser
Show abstract
We have demonstrated a novel approach to achieve a stable multi-wavelength laser system (MWLS) which is making
use of a quantum dot semiconductor optical amplifier (QD SOA) as a highly birefringence material and an optical
polarizer at the same time. Both the channel frequency spacing and the central lasing wavelength of the QD MWLS can
be accurately set by using the desired-designed QD SOA with the certain operation conditions and by setting the
polarization controller properly. The detailed working principles and the experimental results have been reported in this
paper. The proposed QD MWLS technology can be used for characterizing the intrinsic properties of the QD
semiconductor waveguide materials that could also be used for spectral narrowing of a laser system. We have
experimentally confirmed that the QD SOA is highly inhomogeneous gain material as compared with QW SOA.
Synthesis of ultraviolet luminescent silicon nanocrystals by nanosecond pulsed laser ablation in water
Show abstract
We report the preparation of silicon nanocrystals with efficient ultraviolet luminescence by nanosecond pulsed laser ablation in de-ionized water at a high laser fluence condition. Atomic force microscopy results show that nano-grains form in the process of laser ablation. Fourier transform infrared spectroscopy analyses indicate that silicon nanocrystals are formed and partially oxidized during synthesis. The photoluminescence measurement and the ultraviolet-visible transmittance spectroscopy of the samples prepared at various fluences reveal that all the prepared samples present an efficient ultraviolet emission at room temperature and it can be attributed to the quantum confinement effect and surface defect states. The emission wavelength of silicon nanocrystals is far shorter than visible light, which means potential applications in optoelectronic devices.
Optical Switches and Modulators II
Design and fabrication of 2×2 InP/InGaAsP optical switch
Show abstract
An InGaAsP/InP 2×2 Mach-Zehnder interferometer (MZI) optical switch based on multimode interference (MMI) couplers was presented. The switch characteristics were simulated using a three-dimensional beam propagation model. The switch structure was designed to be single mode operation and insensitive to polarization. The light signal can be switched from cross port to bar port with an injection current of 43mA by carrier modulation on the principle of injection free carriers, bend-filling effects and bandgap shrinkage. The measured crosstalk is -19.2dB and -14.3dB at the on and off state, respectively. This optical switch can be easily integrated with other active devices and has potential application in future DWDM and OXC systems.
All-optical SOA-based wavelength converter assisted by optical filters with wide operation wavelength and large dynamic input power range
Show abstract
All-optical wavelength converters (AOWCs) based on nonlinear processes of semiconductor optical amplifiers (SOAs) have attracted interest to overcome the wavelength blocking issues in future transparent networks. While many schemes work well, pattern effect impairments that are due to the finite lifetime of charge carriers are an issue most of the time. Recently, wavelength conversion and pattern effect mitigation techniques that work by properly shaping the passband of filters following the converter have been introduced. However, due to the necessity of selecting filter slope and position precisely, one would expect that the schemes are extremely sensitive to any drift of the center wavelength. In this work, we demonstrate a 40 Gbit/s SOA-based wavelength converter with more than 15 dB dynamic input power range. In addition, the center wavelength of the converted signal has a tolerance of ~0.2 nm towards the red spectral region and of ~0.1nm towards blue spectral region, respectively. This success is due to combining advantageously pattern effect mitigation techniques connected to the pulse reformatting optical filter, the red-shift and the blue-shift optical filter.
Degradation by the cross-polarization modulation of the conversion efficiency of a wavelength converter based on FWM in a SOA
Show abstract
This communication addresses, theoretically and experimentally, the effect of the cross polarization modulation (XPolM)
phenomenon on the performance of a wavelength converter based on a four wave mixing process (FWM) developed in a
semiconductor optical amplifier (SOA). The main studied parameter for evaluating the performance of the wavelength
converter is the conversion efficiency, whose degradation, provoked by the XPolM, is analyzed when the four wave
mixing process is developed with input signals linearly co-polarized at 0, 45, 90, and -45 degrees. The analysis is based
on the theoretical and experimental determinations of the polarization mismatch of the pump and probe signals. Finally,
it is demonstrated that classic models lacking the inclusion of the XPolM effect can reflect a significant error in the
estimation of the conversion efficiency of a wavelength converter based on FWM.
40 Gbit/s FSK all-optical wavelength conversion and NOT gate using periodically poled lithium niobate waveguides
Show abstract
All-optical wavelength conversion is considered to be a key technology in future high-speed large-capcity dense
wavelength-division-multiplexed (DWDM) optical networks. Transparent wavelength conversion is highly desired
especially for various advanced modulation formats. We report a novel 40 Gbit/s all-optical transparent frequency-shift
keying (FSK) wavelength conversion and logic NOT gate by exploiting cascaded second-harmonic generation and
difference-frequency generation (cSHG/DFG) in a periodically poled lithium niobate (PPLN) waveguide. In addition,
transparent wavelength conversions for optical duobinary (ODB) and alternate-mark inversion (AMI) modulation
formats are demonstrated in the experiment.
Novel Active Devices V
Highly stable white light from ultraviolet laser diode
Show abstract
A phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet
(n-UV) light and phosphors that emit in the red/green/blue region when excited by the n-UV light was fabricated.
The relationship of the luminous flux and the luminous efficacy of the white light with injection current were discussed.
Based on the evaluation method for luminous efficacy of light sources established by the Commission International de
I'Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the maximum luminous efficacy of
this white light fabrication method were also presented.
High power diode laser with beam coupling
Show abstract
As the increasing applications of the semiconductor lasers in the laser processing, the single 2-D stack optic-power
density has not satisfied the actual requirements. It demands to couple several diode laser stack beams to one to improve
the brightness, and it becomes the central issue to adopt the appropriate beam coupling technology which would offer
high quality and high efficiency. In this paper, it mainly introduces the beam shaping and the technology of spatial
coupling, polarization coupling, and wavelength coupling. The coupling key elements are presented and indicated.
Finally, the development of the diode laser on beam coupling in our country fell behind through analyzing the statement
of the world. Our lab is studying on polarization coupling and wavelength coupling. We gain some results by phase,d
which the polarization coupling efficiency can achieve 90% for two LD stacks with seven bars whose luminous
wavelength is 975nm and980nm. By two 808nm diode laser coupling effeice the efficiency of 60% can be achieved after
focusing to the beam size of 2x2mm2.
Gain spectrum and saturation characteristics of two-segment semiconductor optical amplifier
Show abstract
Two-segment semiconductor optical amplifier (SOA) is proposed and studied to manipulate the gain and saturation
characteristics of SOA; this kind of SOA is separated into two segments that are electrically insulated from each other by
two split electrodes; the two segments share the same active region and other internal structure. By changing the
injection current density of the front segment or back segment, the saturation output power, bandwidth and gain
compression can be easily controlled. Therefore it is convenient for SOA to meet various application requirements in
optics communication.
Fiber and Waveguide I
Influence of weak optical feedback on the polarization performances of current-modulated VCSELs
Show abstract
Based on the framework of the spin-flip model (SFM), for the GHz level modulation frequency, the polarization
performances of current-modulated vertical-cavity surface emitting lasers (VCSELs) subject to weak optical
feedback have been theoretically investigated. The results show that, for type I polarization switching (PS), under
small signal modulation, the variation of the modulation frequency does not affect the polarization direction of the
VCSEL output, but due to the influence of the optical feedback, the VCSEL output may behave period, doubling
period and chaos state with modulation frequency variation. For the case of the large signal modulation, optical
feedback can result in the generation of a new style of PS with the variation of the modulation frequency.
Temporal-spectral imaging of optical pulses using time lens
Show abstract
Temporal-Spectral Imaging of optical pulses constitutes a technique for the measurement of
fast optical spectral. The experiment to perform real-time spectral analysis of optical pulses in fibre by
time lens is demonstrated in this article. The use of time lens in the demodulation of the grating
wavelengths is discussed in this article.
Optimization of resolution in confocal imaging system
Show abstract
The signal intensity is derived firstly on the basis of point spread function. Then the effect of pinhole radius on
resolution is discussed for different central obstruction rate
ε. According to the simulated plots, the optimum
relationship of axial resolution to pinhole radius and central obstruction rate ε is proposed. Finally the confocal
imaging system is designed and established. The axial response is measured for different pinhole radius.
Experimental results agree well with theoretical analysis. The in-focus images of bar target is obtained by the
confocal imaging system which shows good performance
A study of polymer clad resin with higher modulus for high NA fibers
Show abstract
There has been a rapidly increasing demand for the high numerical aperture (NA) in specialty optical fibers used in
recent high power fiber lasers and remote sensing applications. Various polymer clad resins (PCR) have been reported
aimed for a low refractive index to achieve a high NA, which resulted in a lower modulus. In this study, we report a
novel PCR with a higher modulus whilst maintaining a high NA over 0.44 using newly designed fluorinated oligomer
and monomer having low refractive index and high functionality. Some resins prepared various formulations using
synthesized oligomers and then compared curing speed.
Sensible measurement of localized surface plasmon based on lithographic gratings
Show abstract
The optical diffraction efficiency of lithographic grating was probed in this study. The enhanced
first order spectral diffraction efficiency emerged from localized surface-plasmon excitation of gold
nanoparticles which are alternatively uniformly and randomly spread in grating strips. The sensible
measurement more than traditional method is reported.
Low-loss intersection of subwavelength plasmonic slot waveguides
Show abstract
The properties of crossing for two perpendicular subwavelength plasmonic slot waveguides are theoretically
investigated. Results show when encountering a nano intersection the crosstalk for the direct crossing is around
25%, almost the same as throughput. In terms of symmetry considerations and resonant-tunnelling effect, we
design two types of compact cavity-based structures. Our results show that the crosstalk is eliminated and the
throughput reaches the unity on resonance. Simulation results are in agreement with those from coupled-mode
theory. Taking material loss into account, the symmetry properties of the modes are preserved and the crosstalk
remains suppressed. Our results may open a way to construct nanoscale crossings for high-density nanoplasmonic
integration circuits.
Nanophotonics IV
Properties of nanostructured metamaterials at optical frequencies
Show abstract
A variety of metamaterials has been demonstrated recently that support backward waves and negative refraction
(Negative Index Materials, NIM.) In particular, these materials enable sub-wavelength resolution that makes them even
more interesting, especially in optical domain rather than at microwave frequencies where their unusual properties were
known for decades. We describe below theoretical and experimental studies of the so-called 'fishnet' metal-spacer holearray
metamaterials, which exhibit NIM behavior at optical frequencies, having unit cell size of a few 100s nm. We
demonstrate experimentally that their refractive index can be modulated very fast and very strongly (from -2.4 to -1.5)
around the communication wavelength of λ1.55 um, in good agreement with the FDTD results. We also discuss a
problem of loss compensation in those materials with hefty Ohmic losses by using gain media and local field
enhancement in metallic nanoparticles ensembles that enable SERS.
Femtosecond pulse generation in a C-band quantum dot laser
Show abstract
We have demonstrated femtosecond pulses from a passive single-section monolithic InAs/InP quantum-dot (QD)
semiconductor laser with the active length of 456 µm and the ridge width of 2.5 µm in the C-band wavelength range
from 1528 nm to 1565 nm. The transform-limited Gaussian-pulses are generated at the 92-GHz repetition rate with the
312-fs pulse duration without any pulse compression scheme. The average output power is larger than 13.2 mW for the
injection current of 60 mA. And the lasing threshold current and external differential quantum efficiency are 17.2 mA
and 38%, respectively. The mode-beating linewidth of the proposed QD mode-locked laser (MLL) was measured less
than 20 KHz. We have interpreted that four-wave-mixing (FWM) process and other nonlinear effects within the QD
waveguide gain materials make the major contributions to lock the phase the longitudinal modes of the QD Fabry-Perot
cavity together to achieve this strong self-pulsation process.
Fabrication and characterization of evanescent wave coupled PbS quantum dots fiber amplifier based on sol-gel method
Show abstract
In this paper, size-tunable PbS semiconductor quantum dots were synthesized by sol-gel route and a novel optical fiber
amplifier was proposed. Based on fused tapered fiber coupler, the PbS quantum dots film was deposited in the couple
region and evanescent wave coupled semiconductor quantum dots fiber amplifier was fabricated. Due to the thinned
fiber shape, evanescent wave penetrates into outer surface. When the pumped light are propagated in the evanescent field
area, the evanescent wave of pumped light is absorbed by PbS quantum dots, so the PbS quantum dots are excited from
ground state to excited state. And when the signal light are propagated in the evanescent field area, the evanescent wave
of signal light stimulate PbS quantum dots, the quantum dots return to ground state and release photons which have the
same frequency and phase with signal light. With interaction between the evanescent wave power and the coated PbS
quantum dots film, the light can be amplified. The optical amplification was obtained at 1310nm wavelength with 980nm
wavelength LD as pump.
Fiber and Waveguide II
Guided plasmon polaritons for triangular metallic waveguides
Show abstract
The properties of guided plasmon polaritons supported by a triangular metallic waveguide are presented. The waveguide examined is a metal core with equilateral triangular cross section embedded in an infinite lossless dielectric media. Based on the rotation symmetry of the waveguide, the sketch of the supported fundament modes is given. The fundamental modes can be constructed by a proper combination of the corner modes and surface modes, which can be supported by isolated metal corners and metallic-dielectric interface respectively. The mode properties of the metallic waveguide, e.g., the dispersion and propagation length with the size of the metal core, mode field orientation and field distribution profiles are addressed by using a finite element method. The numerical singularities of the optical field are removed by smoothing the corners with an appropriate arc at the nano meter scale. The guided modes supported by the structure are determined and characterized for both subwavelength and suprawavelength. We find that the corner modes exist in both regimes, while the surface modes only appear in the suprawavelenth. Our results also show that the mode properties preserve a certain kind of symmetry of the waveguides. The degenerate modes exist both for the corner guided modes and for surface guided modes. The first fundamental corner modes is a polarization-independent mode without the cut-off size of the waveguides. Calculations also show how sensitively the mode changes with the corner sharpness. The propagation constant of the corner modes is sensitive to the corner sharpness, while the side modes are unaffected.
Design and analysis of non-polarizing beam splitter in a glass cube
Show abstract
The reflectance and transmittance of thin films at oblique incident angles exhibit strong polarization effects, particularly
for the films inside a glass cube. However, the polarization effects are undesirable in many applications. To solve this
problem, non-polarizing beam splitters with unique optical thin films have been achieved employing a method of
combination of interference and frustrated total internal reflection, the non-polarizing condition expressions based on
frustrated total internal reflection has been derived, and the design examples of non-polarizing beam splitters with an
optimization technique have been also presented. The results of Rp=(50±0.5)%, Rs=(50±0.5)% andΔr=(0±0.3) degree in
the wavelength range of 400-700nm have been obtained. The thickness sensitivity of NPBSs is also analyzed.
High directive antenna based on metamaterial slab with zero permittivity
Show abstract
In the present paper, the properties of an antenna centred at a metamaterial slab with zero permittivity are investigated. It
is analyzed that the antenna can achieve high directive performance. Its half power beam width (HPBW) decreases
monotonically with the increase of the width of the slab. While the gain of such antenna can only be 0dB independent of
the slab's width. When the permittivity deviates form zero to a little positive number, antenna can achieve high gain by
choosing appropriate slab's width due to the transmission resonance. The effect of loss is also analyzed.
Digital polarization encoding based on orthogonal polarization rotation in a semiconductor optical amplifier
Show abstract
We investigate the polarization-dependent mode gains and polarization rotation (PR) of the semiconductor optical
amplifier in pump-probe scheme, and find that the relationship between polarization rotation (PR) and mode gains keeps
well under different pump power. Thus we can simply obtain the PR angle by measurement of the mode gains. Choosing
suitable injected current we realize the orthogonal polarization rotation by pump laser with power of ~3.5 mW. Then we
propose a novel digital polarization encoding scheme and perform it well in a 10-km fiber transmission system with data
rate at 2.5 G-bit/s, which is promising to promote the optical power-equalized encoding communications.
Wide Bandgap Semiconductor Devices III
Characteristics of GaN-based photonic crystal surface-emitting lasers
Show abstract
Characteristics of GaN-based photonic crystal surface-emitting lasers (PCSELs) were investigated and analyzed. We
demonstrated two different lattice constant of the GaN-based PCSEL. One with lattice constant of 290nm emits a blue
wavelength at 401.8 nm with a linewidth of 1.6 Angstrom and shows a threshold energy density about 2.7 mJ/cm2 under the
optical pumping at room temperature. The other with lattice constant of 234nm observed a wavelength at 423.8nm
with a linewidth of 1.1 Angstrom and energy density about 3.5 mJ/cm2. The laser emission covers whole circularly 2D PC
patterns (50 µm in diameter) with a small divergence angle. The lasing wavelength emitted from 2D PC lasers with
different lattice constants occurs at the calculated band-edges provided by the PC patterns. The characteristics of large
area, small divergence angle, and single mode emission from the GaN-based 2D surface-emitting PC lasers should be
promising in high power blue-violet emitter applications. The lasing wavelength emitted from PCSELs with different
lattice constants occurs at the calculated band-edges showing different polarization angles due to the light diffracted in
specific directions, corresponding exactly to Γ, K, and M directions in the K-space. Furthermore, the PCSEL also shows
a spontaneous emission coupling efficiency β of about 5x10-3 and a characteristic temperature of 148K.
Poster Session
Ultra high-speed SOA-based full adder with PolSK modulated signals
Show abstract
A novel scheme for an ultrahigh-speed all-optical full adder based on dual-pump four-wave mixing (FWM), including parallel dual-pump FWM and orthogonal dual-pump FWM, in two semiconductor optical amplifiers (SOAs) is proposed. In this scheme, the polarization-shift-keying (PolSK) modulation format is used, so pattern-dependent degradation can be reduced. The proposed all-optical full adder is simple, compact, and can accommodate ultrahigh-speed operation. By numerical simulation, it is theoretically investigated using the broad-band dynamic model.
The design of large-mode-area single-mode fiber
Show abstract
Based on the frustrated total internal reflection theory, a leaky large-mode-area double clad fiber is
designed. The propagation constants and leakage loss of the fundamental mode LP01 and sub-low order
mode LP11 is investigated by using of the matrix method. Results show that the designed fiber can
operate with single-mode.
Investigation of self-collimation frequencies in 2-D photonic crystals
Show abstract
The self-collimation frequencies (SCFs) in two-dimensional photonic crystals (2-D PhC) have been investigated
systematically by the plane-wave expansion method. In the wave-vector space, the square-lattice 2-D PhCs have some
square-shaped equifrequency contours (EFCs) both for TE modes and for TM modes. Narrow-beam lights with these
frequencies can propagate in the directions normal to the flat borders of the EFCs without any significant broadening,
which is known as self-collimation effect. We consider the 2-D PhCs consisting of a square lattice of air cylinders in a
dielectric material and the 2-D PhCs consisting of a square lattice of dielectric cylinders in air respectively. Calculation
results show how SCFs of TM and TE modes change with the radius of cylinders and the refractive index of the material.
These results can be applied to designing the PhC devices based on self-collimation effect.
Tailoring of quantum dot basic cell towards high-detectivity THz-IR photodetector
Show abstract
In this paper, a high detectivity THZ-IR photodetector based on resonant tunneling spherical centered defect quantum dot
(RT-SCDQD) is investigated. Inserting the centered defect in quantum dot, increases the dipole transition matrix element
and so increases the absorption coefficient considerably (1.05x106~7.33x106 m-1 at 83μm). Therefore the quantum
efficiency in SCDQD structure enhances which leads to increasing the responsivity of the proposed system. We propose
a method for implementation of this complex quantum dot. Attaching the resonant tunneling double barrier to the
quantum dot removes the basic problem of electron collection from deep excited state without applying large bias
voltages. Also, application of the double barrier reduces the dark current. These improvements conclude to ultra high
detectivity of 2.25x109 cmHz1/2/W at 300°K and 83μm respectively.
A cross-linked electro-optic polymer for second order nonlinear optical applications
Show abstract
Electro-optic properties of a cross-linked second order nonlinear optical polymer were reported. This polymer was
synthesized via the crosslinking reaction with cross linker Trimethylolmelamine by doping the chromophores into the
cellulose diacetate system. The crosslinking temperature is 144°C. The electro-optic coefficient was measured to be 7.12
pm/v at 1550 nm after poling. The stability characteristic of electro-optic effects was studied by a combination of the
electro-optic coefficient and dielectric relaxation measurements. Results show that the cross-linked electro-optic polymer
system possesses an excellent long-time stability. The average relaxation time is as large as 5880 days and the relaxation
was modeled by KWW equation. The dielectric analyses show that the temperature dependence of the relaxation time
follows Arrhenius law.
Optimization algorithm for the pump structure of diode side-pumped lasers
Show abstract
The pump structure greatly influences the characteristics of a diode side-pumped laser. To achieve high
absorption efficiency and a homogeneous pump-beam distribution simultaneously, a systemic
algorithm has been established to optimize the pump structure, where multiple reflections occur on the
internal wall of the reflector inside the pump chamber. The absorption efficiency and the deviation of
the absorption distribution are both evaluated for a typical solid-state laser medium. A scheme for
identifying an ideal pump configuration was finally obtained from several determination procedures, in
which all pump structure parameters were taken into account.
A novel design of an efficient, highly reliable, and good beam quality diode side-pumped solid-state
laser is presented. Effort has been done to obtain a highly uniform pumping intensity in the active area,
which simultaneously reduces the effects of thermal gradient. In this design a novel lens duct
configuration is used. By this way a uniform power distribution and a maximum absorption of pump
power is resulted. Numerical analysis also indicates the superiority of the design to other methods such
as direct and diffusive pumping techniques.
Dependence of the nonlinear dynamics of the optoelectronic feedback semiconductor lasers on the continuous variation route of delay feedback time
Show abstract
The dynamics of a semiconductor laser with delayed optoelectronic feedback are theoretically investigated when the
delay time is continuously varied. The results show that, for a fixed feedback time, the output dynamics state of the
semiconductor laser with delayed optoelectronic feedback is dependent on the continuous variation route of delay
feedback time; the bistability can be obtained for a given varying range of the delay feedback time. Further more, by
adding modulation signal, the characteristics of the bistability states become more complex, and some new types of
dynamic bistability states are observed.
Chaotic output signal self-correlation characteristics of optical feedback semiconductor lasers under optical injection
Show abstract
Based on the theory describing the optical feedback semiconductor lasers (SLs) under optical injection, the
effects of the feedback strength and delay time, injected strength and frequency detuning on the self-correlation
performance of the output chaotic signal are investigated. The results show that the full-width at half-maximum
(FWHM) and peak sidelobe level (PSL) of the output self-correlation function is critically dependent on
parameters related to injection and feedback. By reasonably selecting the parameters, the self-correlation
function with 0.02ns FWHM can be obtained, which is prior to reported results.
Down-conversion luminescence properties of Er3+-doped cadmium silicate glasses
Show abstract
The cadmium silicate glass samples of 40SiO2-14Al2O3-(40-x) CdO-2Li2O-2K2O-2Na2O-xEr2O3 (x=0.15, 0.20, 0.25,
0.30, 0.35, 0.40 mol) was prepared by high-temperature solid-state reaction method, and it is pumped at 488 nm, 532 nm
and 800 nm respectively. The results indicate that the main peak wavelengths are at 547 nm, 731 nm and 1534 nm
excited at 488 nm. The relationship of the intensity between the emission light of 731 nm and Er3+-doped concentration
is nonlinear. Near-infrared light nearby 1534 nm is excited at 532 nm and 800 nm, but it is weaker at 800 nm. The glass
samples open a outlook of application for conversion luminescence materials.
Theoretical and experimental study of ASE-injection wavelength-locked Fabry-Perot laser diode
Show abstract
The influence of bias current and ASE injection power on the side-mode suppression ratio (SMSR), relative intensity noise (RIN) and gain of the ASE-injection wavelength-locked Fabry-Perot laser diode (F-P LD) have been studied experimentally. Results show that the SMSR and RIN depend on the bias current for a given ASE, and there is different optimum bias current in terms of the SMSR and RIN. With the influence of detailed spontaneous recombination mechanism and its temperature dependence and the temperature- and wavelength-dependent material gain, we propose a static model of the wavelength-locked F-P LD based on nonlinear etalon theory. The temperature dependence of gain and saturation power of wavelength-locked F-P LD is analyzed theoretically with the model. The results show that the saturation power increases as we increase the operation temperature, while it decreases as we increase the reflectivity of front facet.
Ultra-compact mode-split silicon microring resonator for format conversion from NRZ to FSK
Show abstract
We propose and experimentally demonstrate all optical format conversion from non-return-to-zero (NRZ) format to
frequency-shift-keying (FSK) format based on free carrier dispersion effect in a silicon mode-split microring resonator.
The injection of the high-power NRZ signal generates free carriers leading to the blue shift of the spectrum when a '1'
comes. Therefore, there is a selective filtering for the two probes with certain separation located at different position of
the split mode according to the information carried by the NRZ signal. Then the NRZ signal is converted to the FSK
format. The microring resonator features ultra-compact size with a radius of 10 μm thus is suitable for integration with
silicon-on-insulator (SOI) based optical and electronic devices. The split mode can provide large and variable frequency
deviation for the FSK signal. 1 Gb/s NRZ signal is successfully converted to FSK format with a frequency deviation of
40 GHz, which can find application for interconnection between a metropolitan area networks (MAN) and a passive
optical network (PON) system.
KTN-based electro-optic beam scanner
Show abstract
We report a new type of high-speed electro-optic (E-O) beam scanner based on Potassium Tantalate Niobate
(KTN) crystal. It has larger scanning angle, better angular resolution, and lower driving voltage comparing to the
traditional E-O crystal beam scanner. Compared to conventional moving mirrors such as servo-controlled mirrors and
galvanic mirrors, the demonstrated E-O beam scanner can improve the response time by 100 times. The presented
device has many other unique features such as light weight, small dimension, low power consumption, and no-moving
components particularly suitable for airborne and space-borne applications.
The noise analysis and its suppression in CMOS ROIC for microbolometric infrared focal plane array
Show abstract
The readout integrated circuit (ROIC) for micro-bolometric infrared focal plane array (IRFPA) is
commonly fabricated in silicon complementary metal oxide semiconductor field effect transistor (CMOS)
technology. There are three main categories of noise in a typical CMOS ROIC, which are 1/f noise,
KTC noise and fixed pattern noise. These noises in CMOS ROIC can seriously restrain the dynamic
range of the ROIC and degrade the performance of IRFPA. A new CMOS ROIC for micro-bolometric
IRFPA is designed to suppress the noises, and its performance is successfully verified through the theory
analysis and experimental results in this paper.
Packaging and thermal characteristics of Epi-down bonded uncooled pump lasers
Show abstract
High-power single-mode 980nm pump lasers are the key components in optical fiber amplifier. Thermal management for
the telecom applications is a key design parameter for both package and system level. In this paper, based on the
designed structural and material parameters of Epi-down bonded uncooled 980nm laser, the heat distribution of Epi-down
bonded uncooled pump laser was simulated using the finite element method, and the photoelectric properties of
designed and packaged module were tested. A fiber output power of 200mW was achieved for the Epi-down bonded
uncooled 980nm laser with fiber Bragg grating, and module can work steadily over a wide temperature range of 0~70°C, with a small wavelength shift of 0.2nm, along with a FWHM less than 1.1nm, and a SMSR of more than 45dB.
Tunable laser using semiconductor optical amplifier and its application in fiber grating sensor system
Show abstract
A tunable Fourier domain mode-locked (FDML) laser is designed and realized with Semiconductor Optical Amplifier
(SOA), and laser with wide tunable range and high stability could be acquired. Applying the tunable laser to fiber grating
sensor system could improve Signal Noise Ratio and demodulation precision, enhance the ability of multiplexing and
advance the system performance.
All-optical 20 Gbit/s NRZ-DPSK demodulation and clock recovery
Show abstract
All-optical clock recovery (CR) from 20-Gbit/s nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) signal is
demonstrated experimentally by using Polarization-Maintaining Fiber Loop Mirror Filter and semiconductor optical
amplifier (SOA) fiber ring laser. Only by adjusting polarization controller (PC), NRZ-DPSK signal were conveniently
and fast converted to pseudo return-to-zero (PRZ) signal via PMF-LMF. Then the PRZ signal is injected into the SOA
fiber laser for CR. The recovered clock signals with the extinction ratio of 10 dB and the root-mean-square timing jitter
of 850 fs is achieved under 231-1 pseudorandom binary sequence NRZ-DPSK signals measurement.
Photoluminescence properties of rare-earth doped Si-based films materials
Show abstract
The photoluminescence (PL) spectra at room temperature for the silicon-based samples doped by Nd by ion implantation
are measured. The results show that all the samples possess blue-violet photoluminescence properties under the
ultraviolet light excitation and its light emission is stable. The intensity of PL spectra is closely relative to the dose of
implantation and to the temperature of thermal annealing.The above samples were treated by anodization method. The
PL spectra of porous samples which were treated by HNO3 were measured. The results show light emission efficiency
of the porous samples that were treated by electro-chemical anodization etch and HNO3 is higher than those of ordinary
PS samples under the same measuring conditions.
White light emission from InGaN CdSe/CdS/ZnS quantum dots LEDs
Show abstract
II-VI family semiconductor nanocrystals have attracted most interests in nanometer science and technology recently. The
quantum dots have many applications in optoelectronic device such as LEDs for its superior properties resulting from the
three-dimensional confinement effect of its carrier. Hybrid inorganic/organic electroluminescent devices were
demonstrated using monolayers of CdSe/ZnS core/shell QDs sandviched between two organic thin films. However, the
luminous efficiency of the hybrid in organic/organic device was very low. In this paper, an intermediate shell of CdS was
used as the lattice parameter adaptation layer to improve the core/shell interface quality the luminous efficiency of the
core/shell QDs. White light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chips with luminescent
colloidal core/shell CdSe/CdS/ZnS quantum dots (QDs). Photoluminescence of CdSe/CdS/ZnS quantum dots
demonstrated high photoluminescence efficiency with a quantum yield more than 44%, and size-tunable emission
wavelengths from 380 to 620nm. WLED was successfully assembled by blue InGaN chip plus green and red emitting
CdSe/CdS/ZnS QDs. The InGaN chip white-light-emitting diodes with CdSe/CdS/ZnS quantum dots as the emitting
layer are potentially useful in illumination and display applications.
Deposition of nanocrystalline SiC films using helicon wave plasma enhanced chemical vapor deposition
Show abstract
Hydrogenated nanocrystalline SiC films have been deposited by using helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) in H2, SiH4 and CH4 gas mixtures at different RF powers. Their structural and optical properties have been investigated by Fourier transform infrared absorption (FTIR), atomic force microscopy (AFM) and ultraviolet-visible (UV-VIS) transmission spectra. The results indicate that RF power has an important influence on properties of the deposited films. It is found that in a 300 °C low substrate temperature, only amorphous SiC can be deposited at the radio frequency (RF) power of lower than 400 W, while nanocrystalline SiC can be grown at the RF power of equal to or higher than 400 W. The analyses show that the high plasma density of helicon wave plasma source and the high hydrogen dilution condition are two key factors for depositing nanocrystalline SiC films at a low temperature.
Formation and characterization of ZnS/CdS nanocomposite materials into porous silicon
Show abstract
ZnS/CdS were deposited by chemical vapor deposition (CVD) technique on porous silicon substrates formed by electrochemical anodization of n-type (100) silicon wafer. The optical properties of ZnS/CdS porous silicon composite materials are studied. The results showed that new luminescence characteristics such as strong and stable visible-light emissions with different colors were observed from the ZnS/CdS-PS nanocomposite materials at room temperature.
Technological processes of grating light valve as diffractive spatial light modulator in laser phototypesetting system
Show abstract
Grating Light Valve (GLV) is a kind of optics device based on Micro-Opto-Electro-Mechanical System (MOEMS)
technology, utilizing diffraction principle to switch, attenuate and modulate light. In this paper, traditional GLV device's
structure and its working principle are illuminated, and a kind of modified GLV structure is presented, with details
introduction of the fabrication technology. The GLV structure includes single crystal silicon substrate, silicon dioxide
isolating layer, aluminum layer of fixed ribbons and silicon nitride of movable ribbons. In the fabrication, lots of
techniques are adopted, such as low-pressure chemical vapor deposition (LPCVD), photolithography, etching and
evaporation. During the fabrication processes, Photolithography is a fundamental and fatal technology, which determines
etching result and GLV quality. Some methods are proposed through repeated experiments, to improve etching result
greatly and guide the practical application. This kind of GLV device can be made both small and inexpensively, and has
been tested to show proper range of actuation under DC bias, with good performance. The GLV device also has merits
such as low cost, simple technology, high fill ratio and low driving voltage. It can properly be well used and match the
demands of high light power needed in laser phototypesetting system, as a high-speed, high-resolution light modulator.
Inductively coupled plasma etching of In1-x-yAlxGayAs in BCl3/Cl2/Ar
Show abstract
In this paper, dry etching of In0.8Al0.2As/In0.8Ga0.2As/In1-xAlxAs (In1-x-yAlxGayAs) epitaxy material was studied in
BCl3/Cl2/Ar inductively coupled plasma (ICP). Etching behavior was characterized by varying the BCl3/Cl2/Ar mixing
ratio, ICP power or DC-bias. The results indicate that, in Cl2 dominant condition, smooth surfaces are achieved with
mean etch rate exceeding 2 μm/min. As the ratio of BCl3 increasing, the etch rates decrease monotonously and the
surfaces becomes rougher because of low volatility InClx etch product. ICP power influences the etch rates, and the etch
rates increase monotonously with DC-bias. The result is useful for the fabrication of extended long-wavelength response
optoelectronic InGaAs devices.
Central hole effect on Whispering-Gallery-Mode of triangular lattice photonic crystal microcavity
Show abstract
Whispering-Gallery-Mode (WGM) photonic crystal microcavity is a kind of photonic crystal application and can
potentially be used for miniaturized photonic devices, such as thresholdless lasers. In this paper we study the WGM of
photonic crystal microcavities focusing on the so called H2 cavities which are formed by removing seven air holes. The
WGM in these large-size cavities has some advantages compared with single defect WGM in the view of real device
applications. We further add a central air hole in the cavity region to analyze the effect on WGM in the microcavity by
finite difference time domain (FDTD) and plane wave expansion (PWE). It is found that the tolerance of WGM is large
enough for the fabrication of electrical injection structure.
Wavelength interleaver in a two-dimensional rod-type photonic crystal
Show abstract
A theoretical model of wavelength interleaver, which is based on an asymmetric Mach-Zehnder interferometer (AMZI) constructed in a two-dimensional photonic crystal (2D PhC), is proposed and numerically demonstrated. The 2D PhC consists of a square lattice of dielectric cylindrical rods in air. The AMZI includes two mirrors and two splitters. Light propagates between them employing self-collimation effect. The two interferometer branches have different path lengths. By using the finite-difference time-domain method, the calculation results show that the transmission spectra at two AMZI output ports are in the shape of sinusoidal curves and have a uniform peak spacing in the frequency range from 0.191c/a to 0.200c/a. When the path length of the longer branch is increased and the shorter one is fixed, the peaks shift to the lower frequencies and the peak spacing decreases nonlinearly. Consequently, the transmission can be designed to meet various application demands by changing the length difference between the two branches. For the dimensions of the wavelength interleaver are about tens of central wavelengths, it may be applied in future photonic integrated circuits.
Analysis and simulation of process parameters for epitaxy of InP-based compound semiconductor materials
Show abstract
Under a wide range of process parameters, such as varying total flow rate of gas inlet,
chamber pressure, growth temperature, wafer carrier rotation, it has been finally obtained the
favorable conditions of the better uniform distributions of steady flow and thermal field profiles
for growing high quality compound semiconductor materials inside the reactor. Then, the long-
wavelength metamorphic In0.53Ga0.47As PIN photodetectors grown on semi-insulating GaAs
substrates are successfully demonstrated by low temperature InP buffer technology. The active
area of this photodetector is 50μm×50μm and the thickness of In0.53Ga0.47As adsorption layer is
300 nm. The 3dB bandwidth of frequency response reaches 6GHz. The responsivity of 0.12
A/W to 1550 nm optical radiation, corresponding to the external quantum efficiency of 9.6%,
was achieved.
Novel optical power equalizer and optical hard limiter based on quantum-dot semiconductor optical amplifiers
Show abstract
Novel schemes of optical power equalizer (OPE) and optical hard limiter (OHL) are presented, which base on quantum-dot
semiconductor optical amplifiers (QD-SOAs) and adopt a traveling-wave QD-SOA in each arm of Mach-Zehnder
interferometer (MZI). The function of power equalization and hard limitation can be realized respectively in a wide range
by setting the phase difference between two arms of Mach-Zehnder interferometer.
Optical properties of p-type Al and N co-doped ZnO films
Show abstract
Effect of Al-N codoping ratio on the conducting and optical properties of ZnO films deposited by helicon wave plasma
assisted radio frequency magnetron sputtering under various N2 gas flow is investigated. Hall measurements show that p-type
ZnO thin films have been achieved with proper N2 flow rate. X-ray diffraction patterns indicate that all the films are
highly c-axis oriented. Room temperature photoluminescence spectra show a strong near-band-edge emission. With
increasing N doping, the intensity of the emission behaves an increased and then decreased trend while the full width at
half maximum is narrowed and then widened. In addition, photoluminescence spectrum at 77 K in the p-type ZnO film
with the highest hole concentration show a much stronger peak near 3.32 eV (due to N related neutral acceptor bound
excitons), than at 3.36 eV (neutral donor bound excitons), and the acceptor energy level is estimated to be 186 meV.
Investigation of UV photocurable microcapsule inner crosslink extent
Show abstract
UV photocuring technology has encountered increased applications in recent years, which finds a variety of applications on protective coating of the optical-fiber, ink and optical recording materials. Combined with techniques of photohardenable, microcapsule, heat-sensitive and interface-polymerization method, a novel photoheat sensitive recording material of non-silver salt is explored in this thesis. Microcapsules are particulate substance with a core and shell structure, where photopolymerizable composition, monofunctional/polyfunctional diluents, photopolymerization initiator, photosensitivity enhancing agent and dye precursor are encapsulated as the internal phase. In this paper introduced the characteristics and curing mechanism of photo-sensitive microcapsule materials. The photocuring process may be a complex-function with photopolymerizable compound and photopolymerization initiator. For the sake of high photocuring speed and degree, optimal photo-sensitive materials were selected. In order to match with the light source excitation wavelength and absorb more wider ultraviolet band, combined type of photo-polymerization initiators were employed. With the kinds and dosage of photopolymerization initiator changing, the photocuring speed and quality can be ameliorated. Through studying the UV-visible absorption spectrum and infra-red spectrum of the material , the optical response property of the inner compound can be obtained.
An improved finite-difference beam propagation method and its application in arrayed waveguide grating
Show abstract
Finite-Difference Beam Propagation Method (FD-BPM) in conventional is modified, according to more accurate
Helmholtz equation, a new arithmetic is advanced. By using the new arithmetic and the old arithmetic in calculating slab
waveguide and calculate the parameter which scales the precision of the method and the calculating time, we prove that
the accuracy of the new arithmetic is improved without affecting time performance. At last we calculate the transmission
mode in the AWG by the new method to show the practical value of the modified arithmetic.
Investigation of ultra-fast accurately synchronization control GaAs photoconductive switches
Show abstract
Experiments of a lateral semi-insulating GaAs photoconductive semiconductor switch triggered by nanosecond serial laser pulses were reported. The switches were insulated by solid multi-layer transparent dielectrics. Jitter-free electrical pulses with steady voltage amplitude from the 0.5 mm-gap GaAs switches were observed. Its change of amplitude was less than 1.1%, the triggered jitter-time was less than 10ps, and pulse width was up to sub-nanosecond. The Jitter-free and steady speciality of electrical pulses from the photoconductive semiconductor switch was analyzed. It was indicated that ultra-fast electrical pulse with steady voltage amplitude and pico-second triggered jitter-time can be obtained by controlling switch trigger condition and optimizing switch design.
Flat supercontinuum generation by nanosecond pulses pumped
Show abstract
Microchip-laser-pumped supercontinuum (SC) is successfully generated through a 30-m long photonic crystal fiber
(PCF). The spectra bandwidth of SC is 850 nm spanning from 550 nm to 1300 nm. The -15dB-flat bandwidth is 400 nm
spanning from 600 nm to 1000 nm. It is easy to achieve a much more flat SC with the sacrifice of spectra bandwidth. A
detailed simulation is carried out to help us understand more about the supercontinuum generation process. The primary
mechanism of spectral broadening is identified as parametric four-wave mixing (FWM) combined with stimulated
Raman scattering (SRS). These findings also demonstrate an effective way to generate a flat supercontinuum laser source.
The effect of water resistance in the primary coating by silane coupling agents and amine synergists
Show abstract
In order to clarify the relationship between the water resistance and compositional additives in the primary coating for optical fibers, we prepared various primary coatings that contained silane coupling agents in combination with amine synergists. We observed the appearance of the interface between glass and primary coating after soaking in water at 65° for 30 days. Water resistance was found to be heavily influenced by the content and type of silane coupling agents and amine synergists and their trends are reported.
Synthesis and nonlinear optical properties of novel fluorinated polyimides with thiazolylazo chromophores for electrooptic devices
Show abstract
A series of novel fluorinated polyimides second-order nonlinear optical (NLO) materials were synthesized from poly(hydroxy-imide)s, followed by the Mitsunobu reaction with NLO thiazolylazo chromophores. The polyimides prepared were characterized by IR, UV-vis, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetric analysis (DSC) and X-ray diffraction (XRD). These NLO polyimides possess high glass transition temperature (Tg) in the range of 193-200 °C with thermal stability up to 288 °C. The electro-optic coefficients (r33) at the wavelength of 1550nm for polymer thin films poled were measured by the attenuated total reflection (ATR) method. The r33 values of the polyimides 1a and 2a containing thiazolylazoaniline chromophore are better than that of the polyimides 1b and 2b attached thiazolylazopyrimidine chromophore, due to the thiazolylazoaniline chromophore having large hyperpolarizability in contrast to the thiazolylazopyrimidine chromophore. Low optical losses (1.8-2.1 dB/cm at 1.55 μm), which were measured via an immersion technique have been observed for these polymers. The polyimides demonstrate an excellent combination of thermal stability, electrooptic (EO) coefficients and optical loss, and therefore they are suitable for EO applications.
Pulse-LDA-pumped passively Q-switched Nd:YVO4 laser with GaAs as saturable absorber
Show abstract
A passively Q-switched pulse-LDA (laser diode array)-pumped Nd:YVO4 laser using As+ implanted GaAs as the saturable absorber is demonstrated. In the experiment, a Q-switching pulse width 7ns with a pulse energy 23.5μJ is achieved which, to our knowledge, is the shortest pulse width in a passively Q-switched Nd:YVO4 laser using GaAs as saturable absorber. The laser emits only one Q-switching pulse during each pump-pulse time with a Q-switching efficiency of 26.8%. We also investigate the characteristics of the Q-switched pulse by adjusting the pumping pulse energy, pulse width and pulse repetition rate respectively. The experimental results are discussed as well in the paper.
Influence of annealing environment on the hydrogen related bonding structure in silicon nitride thin films containing silicon nanoparticles
Show abstract
The Si-rich SiNx:H films have been prepared by helicon wave plasma-enhanced chemical vapor deposition (HWP-CVD) technique. Parts of the samples have been post-annealed at 800 °C in the H2, FG (10%H2 in N2), and N2 ambient, respectively. Fourier transform infrared spectroscopy (FTIR) and the optical absorption spectroscopy have been used to investigate the influence of different annealing environment on the structural and optical properties of the films. After the thermal annealing process, there is a significant increase of Si-N bonding density. Meanwhile, the band related to hydrogen (N-H and Si-H) decreased which indicates that the hydrogen is effused out of the films during the annealing treatment. The Si-sH stretching vibrations can be divided into three components by Gaussian distribution; the Si-H absorption band at different wave numbers corresponds to different configurations. The changes of the three peaks contributions decreased indicate that the configurations of the Si-H stretching vibrations band occurs restructuring in the different annealing environments. Furthermore, the investigation of the optical absorption spectroscopy suggests that the band gap Eg decreased after the thermal annealing process. The decreased optical gap should be related to the loss of hydrogen and the slightly increase in the mean size of silicon nanoparticles, which is in good agreement with that of the hydrogen bonding structure.
The designs of XOR logic gates based on photonic crystals
Show abstract
All-optical logic gate based on photonic crystal waveguides is a promising technique in future high-speed all-optical
signal processing. In this paper, we propose a XOR logic gate based on two dimensional triangular lattice photonic
crystals composed of cylindrical silicon rods in air. The main structure of the device is a line defect asymmetric Y
branch waveguide. It is expected that there should be a phase shift between the two input beams. Hence, if an
appropriate initial phase is introduced, the two input beams may interfere constructively or destructively to realize the
logical functions. The simulation results show that the proposed all-optical photonic crystal waveguide structure could
really function as XOR logic gates. The interference section length and width of photonic crystal waveguide structure
are optimized for achieving the optimal performance for the proposed XOR logic gates. This device is potentially
applicable for photonic integrated circuits.
3×3 coupler-based dual microring resonator array: model and analysis
Show abstract
Dual microring resonator array coupled via 3×3 couplers are studied using matrix formalisms. Transmission spectra are
investigated as functions of column numbers and coupling coefficients in detail. Multiple transparent peaks appear when
the column number increases for arrays of the first two types. The spectra for arrays of the other two types show
complicated characteristics as functions of coupling coefficients.
Optical properties of protocrystalline silicon/amorphous SiC multilayer films
Show abstract
Protocrystalline silicon/amorphous SiC multilayer films were fabricated by helicon wave plasma enhanced chemical vapour deposition (HW-PECVD). Atom force microscopy, Raman scattering and optical absorption measurements were used to analyze the microstructure and optical properties of the multilayer films. Experiment analyses reveal that through inserting transient a-SiC layer into film depositing process, well-controlled pc-Si:H films have been obtained in the growth condition of the μc-Si:H. The optical gap is observed being tuned from 2.15 to 2.43 eV by varying single pc-Si:H layer thickness. Such multilayer structure should have potential application in constructing high efficiency and stable Si-based solar cells.
High power 1064nm laser diode array and measuring chip temperature based on emitting spectra
Show abstract
High power laser diode array with an emission wavelength of 1064nm is presented. The epitaxial structure is an
InGaAs/GaAsP strained-compensated single-quantum well structure. The modules CW output power can reach to 56.5W
at current of 80A. Because the heat capacity of st rather shorter pulse duration and lower duty cycle, the average driving
power in the laser chip is quite low, so the heating effect cemiconductor laser is very small, using pulse injection can
reduce temperature rising significantly. Aould be neglected. The definite relation between lasing wavelength and chip
temperature is developed. The temperature drift coefficient is 0. 45nm/ K
Temperature characteristics of several familiar diode lasers with broad area
Show abstract
Temperature characteristics of several familiar high power diode lasers with broad area, whose wavelength was
separately 808 nm, 810 nm, 940 nm and 980 nm, were analyzed. In order to see the effect the change of the quantum
well structure on the characteristic temperatures, different structures were attempted. For the 808 nm structure, we tried
different barrier thicknesses. For the 810 nm structure, different cavity lengths were attempted. And we studied the 940
nm and 980 nm also. In this paper, the widths of these devices were all 100 μm. Characteristic temperatures of these
devices were calculated. The appropriate structure was available for different application.
High performance blue light-emitting diodes on patterned Si substrate
Show abstract
High quality crack-free GaN layers were successfully grown and the InGaN/GaN based blue LEDs
fabricated on patterned Si (111) substrates. In addition to using the patterned growth technique, thin AlN and SiNx
interlayers grown at high temperatures were also employed to partially release the residual stress and to further
improve the crystalline quality. 300 µm square blue LEDs fabricated on the islands, without thinning and package,
exhibited a high output power of around 0.68 mW at a drive current of 20 mA.
Vertical external cavity surface-emitting lasers: numerical simulation and characterization
Show abstract
Firstly, the vertical external-cavity surface-emiting lasers (VECSELs) device structure and
model was given, and the output characteristic was simple calculated. Then, in experiment, the
VECSELs were grown, bonded on to the heat sink, and optically pumped by high-power 808nm diode
laser array with fiber output module, the light emission spectra were measured. Finally, The thermal
characteristic of the VECSELs was investigated by changing the temperature of the substrate.
Strain engineered quantum dots for long wavelength emission
Show abstract
A systematic investigation about the strain distributions around the InAs/GaAs quantum dots using the finite element
method is presented. A special attention is paid to the influence of InGaAs strain reducing layer. The numerical results
show that the horizontal, vertical strains components and the biaxial strain are reinforced in the InAs quantum dot due to
the strain-reducing layer. But the hydrostatic strain in the quantum dot is reduced. In the framework of eight-band k • p
theory, we studied the band edge modifications due to the presence of strain reducing layer. Results demonstrate that, the
strain reducing layer yield the decreasing of band gap, i.e., the redshift phenomenon observed in experiments. Our
calculated results show that the degree of the redshift will increase with increasing of the thickness of strain-reducing
layer. In calculating the influence of SRL, we discussed two circumistances: the height of the strain reducing layer larger
and smaller than that of QD. The composition of the strain reducing layer on the degree of redshif is also investigated.
The calculated results can explain the experiment results in literatures, and further confirmed that the long wavelength
emission used for optical fiber communications is realizable by adjusting the dependent parameters.
Optical controllable high-speed switch based on organic coumarin
Show abstract
A novel high-speed optical switch based on organic coumarin waveguide is presented. The device principle is based on
influencing the bend loss in a waveguide by changing the refractive index contrast defining the guide. A low power
femtosecond laser is used to excite the cladding of the curved waveguide. The beam propagation method is employed in
the numerical simulation. The designed optical switch has a large extinction ratio and rapid response time (about 1.2ps).
Synthesis and characterization of silver sols for fiber-optic surface-enhancement Raman scattering
Show abstract
A method of synthesis of silver sols is introduced and characterized, which is easily made, reproducible and convenient
to combine with optical fiber. In a series of experiments, the hot spots in the mixture of silver sols just prepared and R6G
should be chosen to get the high signal-to-noise Raman spectra (RS) of analyte molecule. Surface-enhancement Raman
spectrums (SERS) of R6G are obtained in the form of thin film and liquid drop.
The dynamics of frequency upconversion in Er3+/Yb3+-codoped PLZT transparent ceramics
Show abstract
The luminescence decay curve from transitions of 4I 13/2->4I15/2 in the Er3+/Yb3+-codoped PLZT transparent ceramic was measured. A model for the dynamics of frequency upconversion in Er3+/Yb3+-codoped PLZT transparent ceramic based on the rate equations was proposed. The dynamics of the upconverted emissions were studied to evaluate energy transfer rates between Er3+ and Yb3+ ions, and the forward energy transfer rate for Yb3+ to Er3+ and the backward transfer rate for Er3+ to Yb3+ were 7.19x10-17 cm3s-1 and 3.73×10-17 cm3s-1, respectively.
Theoretical modelling of dipole photoconductive antenna for continuous-wave terahertz emission
Show abstract
Photoconductive antenna as continuous-wave terahertz photomixer has attracted much attention in these years. Its main restriction is the limited terahertz radiant power. In this paper, terahertz emission from dipole photoconductive antenna structures based on the photomixing mechanism has been studied. The terahertz output power is proportional to the radiation resistance of the antenna, the square of dc conductance and that of bias voltage. The photoconductive antenna radiation impedance as a function of frequency has been calculated numerically. And results reveal that the dipole photoconductive antenna design dominates the properties of the radiated output at resonant frequencies below 1THz, while the efficiency at higher frequencies is additionally dependent on the design of the interdigitated fingers, the effect of which is modeled by a lumped capacitance in parallel with the photoconductive area.
Numerical simulation of all-optical wavelength conversion of DPSK signal based on SOA in a Mach-Zehnder configuration
Show abstract
All-optical wavelength conversion of differential phase-shift keyed (DPSK) signals based on SOA in a Mach-Zehnder interferometer (SOA-MZI) configuration is simulated and analyzed using the transfer function of MZI and a wideband dynamic model of SOA. The operation principle is analyzed and operation point selection, influence of SOA physical parameters, different signal format and operation speed are discussed in detail.
The results of 10Gb/s operation show that SOA-MZI is compatible with both non-return-to-zero (NRZ) and return-to-zero (RZ) formatted signals. However, the conversion performance is sensitive to the operation point of the involved SOAs. To maximize the Q value of the demodulated conversion signal, the power and wavelength of the original DPSK signal and the probe light should be optimized to obtain approximately π phase difference between the upper and lower arms of MZI in the middle of each bit. Besides, SOA with short carrier lifetime and large linewidth enhancement factor is preferred for wavelength conversion applications. 40Gb/s operation is also simulated with SOA carrier lifetime of 100ps, and the results strongly suggests 40Gb/s operation with RZ formatted signals and relatively large input powers of the clock signal.
Plasmon-enhanced luminescence from nanocrystalline SiC films through adjusting spacer layer thickness
Show abstract
We report the photoluminescence enhancement of nc-SiC films by coating nanostructure Ag films and study the
influences of surface plasmon on photoluminescence properties by varying spacer thickness. PL curves of the samples
deposited with different thickness of α-SiNx present two PL peaks which are contributed to the interference in the films
and surface plasmon resonance, respectively. The PL intensity of the sample coated with Ag film is quenched due to
combination of Forster nonradiative process and coherent photonic mode reduction in nc-SiC films, while the PL
intensity of the samples with inserted spacer α-SiNx is enhanced because of the surface plasmon resonance.