This PDF file contains the front matter associated with SPIE Proceedings Volume 8555, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.

In this article, two dimensional (2D) metallic gratings of different period and silver nanocubes are fabricated and used as the SERS substrate. The SERS signals of rhodamine6G (R6G) on different substrates are compared. Experimental results show that the SERS signals is much weaker if the R6G molecules are placed on the bare silver film, but the signals will be greatly enhanced if the substrates are composed of both the silver nanocubes and metallic gratings. We attribute this enhancement to the coupling between localized surface plasmons and propagating surface plasmons. Further, we study SERS signals from different parts of the 500nm and 1000nm period 2D metal gratings including the silver nanocubes. The grating of smaller period shows more reproducibility, which arises from the uniformity in the incident laser coverage.

Here we demonstrate a new class of designer plasmonic materials for use in the mid-infrared (mid-IR) region of the electromagnetic spectrum. By heavily doping epitaxially-grown semiconductor materials, we are able to grow single-crystal materials whose optical properties in the mid-IR mimic those of metals at shorter wavelengths. We demonstrate materials with plasma frequencies from 5.5-15μm and low losses, compared to their shortwavelength counterparts. In addition, we demonstrate the ability of subwavelength particles formed from our materials to support localized surface plasmon resonances, and measure the near-field absorption of these structures using a novel nanoscale infrared spectroscopy technique. Finally, we show good agreement between our observed results and analytical and finite-element models of our materials and structures. The results presented offer a path towards nanoscale confinement of light with micron-scale wavelengths.

Recently, dielectric loaded surface plasmons (SPs) elements are inducing highly interesting in the field of nanooptics, which are composed of dielectric nanostructures fabricated on a metallic thin film. This configuration will provide a route to novel integrated micro-optical devices and components combining photonics and electronics on the same chip. The advantages are easy fabrication, easy integration, and also the potential to realizing active plasmonic devices. In this talk, we will present our recent work in this field. Polymer (PMMA) nano-structures are fabricated on a silver film by the electron beam lithography (EBL) and laser interference lithography. These nano-structures are used to manipulate the behaviors of the SPs, such as converging, diverging, and guiding the propagation of SPs in subwavelength scale. Except for the pure PMMA nano-structures, dye materials (Rhodamine B, RhB) doped PMMA structures are also fabricated on the silver film. The RhB molecules will work as the active medium to excite the SPs or compensation the loss of SPs wave. The dye doped PMMA nanostructure provides a choice to realize active plasmonic elements, such as SPs Bragg gratings. On the other hand, the interaction between the fluorescence molecules and SPs will give rise to some new optical phenomena, such as directional fluorescence emission, anisotropic fluorescence emission. These polymer based plasmonic structures are investigated with a home-built leakage radiation microscopy (LRM).

A new type of subwavelength plasmonic waveguide based on a core-shell structure has been proposed. It is based on a semicylinder-shape dielectric-loaded plasmonic waveguide supporting the excitation of surface plasmon polaritons (SPPs). Simulation results reveal that the proposed waveguide exhibit a better trade-off in terms of mode localization and propagation length when compared to the traditional dielectric-loaded plasmonic waveguide. In addition, a ring resonator formed with the proposed waveguide shows a perfect performance with 1.8nm bandwidth and 23dB extinction ratio.

A simple dual-core single-polarization single-mode (SPSM) photonic crystal fiber (PCF) is proposed. It has ultra-wide band and short coupling length, which can be tuned by the design parameters. Most importantly, the simultaneous low confinement loss transmission of 1.30/1.55μm can be obtained in the SPSM region. Also, the wavelength division demultiplexer(WDDM) can be realized by using this kind of PCF.

We propose a compact Terahertz (THz) wave broadband reflector based on the effect of guided mode resonance in photonic crystal slabs. The photonic crystal slabs consist of a square array of circular air holes in silicon. A novel method based on a map of localized bandwidth with defined reflectivity is introduced to analyze the impact of normalized thickness and hole size. The rigorous coupled-wave analysis (RCWA) technique is then applied to analyze its performance. The numerical simulations show that the proposed configuration can offer a broadband frequency range from 2.27THz to 2.89THz with beyond 95% reflectivity.

A thin photochromic film on top of the resist layer can be used as a virtual mask to fabricate super-resolution lithography patterns. In this letter, based on the azobenzene polymer, the absorption intensity of the 365nm LED is effectively modulated by 532nm laser, the modulation degree reaches to 87%.When the silver nanocubes are dropped onto the surface of the polymer film, the modulation degree is significantly higher than that without the nanoparticles in the same intensity of 532nm laser due to the field enhancement of excitation of surface plasmons. The absorption modulation features of the polymer film are favorable for the further smaller line width nanolithography.

Based on the few-mode fiber Bragg grating’s reflection characteristics, we propose and demonstrate a transverse modes switchable fiber laser fiber laser, fundamental mode and 1st higher order modes, and the states be switched by tuning the laser’s oscillating wavelength. The radial vector beam is also obtained by splitting the degenerated 1st higher order modes.

Single quantum dot-cavity system with a deep confinement potential quantum dot is detailedly investigated, with both s- and p-exciton incoherent pump. Through gradually increasing pump rate (about 10^-4=ps ∼ 12=ps), the mean photon number shows a linear-dependence on pump power, the photon probability distribution, characterized by g⁽²⁾(0), transforms from antibunching to bunching through Poisson, and the spectra go from the doublet to a singlet, the linewidth shows clear reduction in the lasing region. If we increase pump rate further, the mean photon number decreases monotonically to zero, g(2)(0) reaches its maximum value 2, and all the electrons stack at upper lasing level, indicating thermal light generation. The results show, the deep QD-cavity system under s- and p-exciton pump can generate laser although it is not an ideal coherent light, and with only p-exciton pump considered, in spite of the coherent light generated, this pump method is unreasonable to simulate the experimental conditions for the negligible energy spacing between s-exciton and p-exciton.

We have proposed a novel approach of realizing all-optical logic gates and combinational circuit using external cavity based single mode Fabry-Pérot laser diodes (SMFP-LDs). Different techniques and critical parameters for injection locking the any one of the modes of SMFP-LDs are discussed. Taking consideration of wavelength detuning and input injected power, we have proposed and demonstrated multi-input injection locking, supporting beam injection locking with the conventional injection locking which are used for demonstrating different logic gates (NAND, AND, XNOR, XOR, NOT, NOR) and digital circuits (Half adder and Comparator). Since we have used SMFP-LDs, there is no requirement of additional probe beam and associated components as required by other optical technologies making the realization simple in configuration, cost effective and power efficient. Clear output waveforms, eye diagrams, risingfalling times and BER are presented to verify the proposed method. All-optical logic units and digital circuit are demonstrated at the data rate of 10 Gbps with the waveform of NRZ signal waveform and measured eye diagram and BER of the PRBS of 2³¹-1 signal. The maximum power penalty among all demonstrated units is below 1.4 dB at the BER of 10^-9.

Indium tin Oxide (ITO) is widely used in touch panel as a conductive material. However, it is fragile and has low transparency in low resistance. In this paper, a ITO-free transparent conductive film (TCF) has been proposed. Micronano structured patterns are designed to induce the silver paste composed by nano silver particles and organic solvents, which form the circuit of touch panel sensor conveniently. Mesh patterns are fabricated by UV nanoimprinting technology to form microgrooves on flexible polymer films coated by UV adhesive such as PET (polyethylene terephthalate). And then nano silver ink is filled into the grooves which constitute the conductive area of the TCF. The optical performance including the transmittance and haze of the TCF is tested. Finally, the TCF with the transmittance 87% and the square resistance less than 50 Ω/sq will be obtained, which can satisfy the applications in touch panel devices.

Multi-wavelength fiber lasers are under intense research due to their potential in many application fields like wavelength-division-multiplexing communication, fiber-based sensing, ranging, microwave photonics and terahertz generation, etc. In this manuscript, we will present our detailed investigation on tunable high power multi-wavelength double-clad fiber laser pumped by high-power multimode laser diode. The fiber laser is constructed in a ring-cavity. By adjusting the polarization-controller inside the cavity, the laser can operate at single-wavelength, dual-wavelength and triple-wavelength regime. The maximal output power is 5.5 watt and the conversion efficiency is 68.8%.

A tunable triple-channel-wavelength fiber laser based on a digital-micromirror-device (DMD) is demonstrated. The DMD processor is controlled by a FPGA system to load grating image to the device storage, and the device driver switches the pixels array to generate reconfigurable reflective digital diffraction gratings on DMD surface. When light irradiates on DMD, corresponding wavelengths are selected and sent to erbium-doped fiber amplifier (EDFA). Hence, a multiple-wavelength laser is generated with laser line - width of 0.02nm. The tunning is fine enough to cover the C-band with a step of 0.08nm and the side mode suppression ratio (SMSR) is larger than 50 dB at room temperature. The switching speed of DMD to generate new gratings on the array is as fast as 1.92 ms.

A scheme of all-optical QPSK signal regeneration is proposed which based on cross phase modulation (XPM) in semiconductor optical amplifier (SOA) with subsequent an optical filter. Simulations and theoretical analysis are conducted to validate the feasibility of the proposal. The QPSK signal is distorted by the negative chirp after fiber transmission, and then the distorted QPSK will be regenerated due to the positive chirp which is induced by XPM in the SOA. A power penalty 2.3dB is improved after QPSK regeneration with the receiver sensitivity of -30.7dBm.

In this paper, a novel optical generation of millimeter waves based on the birefringence in a single-mode fiber ring cavity is proposed and investigated theoretically. The input pulsed laser stimulates two orthogonal eigen-modes in a single-mode fiber ring cavity, the birefringence of single-mode fiber causes a phase mismatch for the two eigen-modes, this phase mismatch leads the generation of millimeter waves, out of the ring cavity a pigtail polarizer is used to combine the two eigen-modes, and then the millimeter wave signal is obtained by using heterodyne method. The effects of straight- through coupling coefficients, phase delay factor, and refractive index difference on millimeter wave signal are discussed.

All-optical modulation at telecommunication wavelength is theoretically studied and simulated by using the gain modulation effect in side mode injection locked multi-mode Fabry-Pérot laser diode (FP-LD). Research results show that the output probe signal with modulation depth of about 8 dB can be achieved in the end of the device, and the corresponding response time is in the picosecond regime. In addition, the properties of outcome signal are strongly dependent on the peak level of input controlling signal, operation speed, and frequency detuning between injection signal and probe wave.

One of the current research trends in silicon photonics is to integrate many kinds of optical functionalities on a single chip. In this paper, based on Silicon-on-Insulator (SOI) we design a tunable filtering waveguide consisted of a Fabry-Pérot cavity and a straight waveguide. The Fabry-Pérot cavity is used for wavelength selectivity and the waveguide is used for light guide. The transmission characteristic of the device has been numerically simulated. The result shows that the Full-Width Half-Maximum (FWHM) is inversely proportional to pairs of the DBR. The tunable filtering waveguide can be integrated with waveguide photodetector, and hopefully to be used in WDM system.

In order to obtain the suitable photocathode which could be applicable for the field of ocean exploration, the p-type zinc (Zn)-doped reflection-mode GaAlAs photocathode sample using exponential-doping technique is grown by metal organic chemical vapor deposition, the Al component of GaAlAs emission layer is designed to be 0.63. After the chemical etching, the photocathode samples are heated in vacuum at high-temperature of 650°C and 600°C respectively, the vacuum variation curves during the heat cleaning are measured, which correspond to the desorption of oxides in the surface of GaAlAs emission layer. The (Cs, O) activation for the photocathodes is executed after heat cleaning. Different proportion of Cs and O is performed on the different photocathode samples. The activation photocurrent curves of two samples with different heat cleaning temperature show that the GaAlAs surface treated by higher heat cleaning temperature is more sensitive to the Cs-O adsorption. The photocathode activated with the larger Cs current has a shorter time to reach the first photocurrent peak, and also obtains a bigger final photocurrent peak. According to the measured spectral response curves, it could be found that a suitable heat cleaning temperature and a moderate Cs/O current ratio are very important to prepare high performance GaAlAs photocathode. The prepared reflection-mode GaAlAs photocathodes are response to the blue-green light, and the cut-off wavelength is at about 580 nm.

Add/drop filters are key components of Wavelength Division Multiplexing (WDM) communication systems. Free spectral range(FSR) is a key parameter for Add/drop filters, the FSR should operate within the entire C-band (1530-1562nm).And flat-top drop-port response with a sharp rolloff is also import, Flatness of the passband, sharp roll-off from passband to stop band are necessary to minimize the pulse broadening and the packing efficiency of wavelength channels. In this paper, we proposed an asymmetric approach to design high-order microring filters, The aim is to achieve large extension ratios and adequate suppression of the spurious interstitial mode, meanwhile, flat-top and steep-side response in filter could be obtained by this approach. Our simulation results showed an extended FSR of 40nm, reducing the interstitial peak suppression from 5dB to 35dB and a boxlike filter response with sharpe factor(SF) of 0.68. And a quality-factor of 2961 and a 3-dB bandwidth of 0.52nm is achieved.

A coplanar lumped electroabsorption modulator (Co-LEAM) based on n-type InP substrate is designed and fabricated, which shows a capacitance of 0.62 pF and a high reverse breakdown voltage (VBR) nearly -26 v. Other characteristics are compared with the common LEAM with the back n-electrode.

In this paper, we proposed a novel photodetector composed of cascaded microring resonators on silicon-on-insulator. In order to enhance the tolerance of signal wavelength drifting in optical communication, the photodetector was designed with a flat-top steep-edge response. In the photodetector, we used polarization insensitive cascaded silicon microring resonators as optical filter cavity, and used a silicon racetrack resonator bonded in p-i-n chip as optical detecting cavity. We used finite element (FE) mode solver, finite different time domain (FDTD), and transfer matrix method (TMM) to simulate the behavior of the polarization insensitive optical filter. With optimized parameters, the photodetector showed high quantum efficiency, narrow line width, and flat-top steep-edge.

GaAs/Si and InP/GaAs wafers growth was performed by low-pressure metal-organic chemical vapor deposition (LPMOCVD) using a two-step growth method. The wet chemical etching methods were used to characterize the dislocations density. For the GaAs/Si wafer, the chemical etching was performed in molten KOH at temperatures about 350°C and for duration about 1.5min. For the InP/GaAs wafer, the chemical etching was performed in H3PO4: HBr (2:1) solution (Huber etchant) at temperatures about 20°C and for duration about 2min.Then, the morphology of the dislocations characteristics of the etch pit density (EPD) were examined with a high-resolution field-effect scanning electron microscope (SEM). There are some ellipse dislocations pits of the GaAs/Si wafer with a density about 2.0x10⁷cm^-2, and sizes ranging from 700nm to 1500nm in diameter, and there are many sunken dislocations pits of the InP/GaAs wafer with a density about 2.0x10⁸cm^-2, and sizes ranging from 300nm to 700nm in diameter. So the method has been accurate and convenient to show the dislocations characteristics of metamorphic GaAs/Si and InP/GaAs wafers.

A 1.65μm three-section Distributed Bragg Reflective (DBR) laser for CH₄ gas sensor was reported. Wide tunable range covering R3 and R4 methane absorption line manifolds. Wavelength tunable properties and temperature stability were characterized and analyzed. Several advantages were demonstrated compared with traditional DFB laser in harmonic detection method.

A novel technique for instantaneous frequency measurement of unknown microwave signal based on both phase modulation and intensity modulation is theoretically and experimentally demonstrated. Based on the output microwave power through dispersive fiber links, three amplitude comparison functions (ACFs) are established, which are combined to measure the frequency of input microwave signal with improved measurable range and accuracy. In the frequency estimation process, the measured calibration ACFs are utilized as the look-up table. The experiment results show that measurement error smaller than 200 MHz can be obtained for the frequency from 0.5 GHz to 20 GHz.

InAs/GaAs quantum dots (QDs) were grown by Metal-Organic Chemical Vapour Deposition (MOCVD) in the Stranski-Krastanow growth mode. The influence of growth parameters such as V/III ratio, growth temperature, QDs deposit thickness and the deposition rate of the overgrowth layer have been investigated. Through the room temperature photoluminescence (PL) spectra, we have obtained the quantum dots’ characters. The growth of QDs is very sensitive to the parameters, and the parameters influence the QDs quality nonlinearly. After an extensive study of these growth parameters, we achieve a balance of all the growth parameters with which InAs/GaAs QDs with 80meV of full width at half maximum (FWHM) at 1.12μm have been achieved.

Graphene, due to its linear energy band structure and the Pauli blocking principle, exhibits broadband optical saturable absorption. We experimentally demonstrated the saturable absorption in graphene with different layers at 800 nm. By performing the balanced twin-detector method, we are able to characterize the nonlinear optical property of the as-fabricated different layer graphene samples. Under strong illumination, we find that absorption of graphene decreases with the increase of incident power, and by fitting the experiment data with theoretical model, the saturable intensity and the normalized modulation depth is measured to be 7.911 GW/cm² and 10.6% in 3 layers sample and 2.77 GW/cm² and 73.6% in monolayer sample, respectively. The experimental result shows that graphene may be a promising saturable absorber, with the potential laser photonics applications, such as laser mode locker or Q-switcher, at 800 nm band.

We have investigated novel optical-wireless architecture to provide WiMax orthogonal frequency division multiplexing (OFDM) signals over fiber access network by simulation. The proposed architecture utilizes direct detection for WiMax OFDM. The simulation results show that it can transmit a high capacity WiMax OFDM signal over 250km SMF successfully.

Based on the definition of beam propagation factor, the relation between beam propagation factor and normalized frequency of TE1 mode of planar waveguide is presented. As the value of beam propagation factor of TE1 mode is close to three for a certain range of normalized frequency, it is rational that the field distribution of TE1 mode of dielectric planar waveguide is expressed by the first order Hermite-Gaussian approximation. When the equivalent mode field half width expressed by the geometric mean of the two kinds of mode field half widths based on the differential operator definition and the second moment definition is employed as the waist size of Hermite-Gaussian approximation, the matching efficiency between the TE1 mode field of planar waveguide and its first order Hermite-Gaussian approximation is near to unit for a certain range of normalized frequency. For giving the characteristics of the beam propagation factor and equivalent mode field half width obviously, the fitting expressions for beam propagation factor of TE1 mode field of planar waveguide as function of normalized frequency and the equivalent mode field half width of the first order Hermite-Gaussian approximation as function of normalized frequency are suggested respectively.

A new scheme of demodulating DPSK signal is proposed based on structure of differential delay interference which is suitable for variable bit-rate and the tuning speed is faster than the existed demodulator. The demodulation of variable bit-rate NRZ-DPSK formats of 10Gb/s and 40Gb/s are demonstrated, the BER after demodulating is lower than 10^-9. It is proved that this demodulator can be used to demodulate 10Gb/s to tens Gb/s bit rate DPSK signal. The demodulator can realize one-, half-, or quarter-bit delays for DPSK signals. Compared to other DPSK demodulators, this demodulator is tunable and the tunable speed is faster.

In this paper, the silicon avalanche photodiode (Si-APD) size in micron, which was comprised of separate layer of absorption charge and multiplication (SACM) has been studied. The influence of different thicknesses and different doping concentration of the absorption, charge and multiplication layer on the electric field distribution, current-voltage characteristic and breakdown voltage were simulated and analyzed respectively. The structural parameters optimization has be done with the simulation results. The results show that the better gain and low bias voltage can be achieved with layer thicknesses in micro/nano-sized, which can give a high gain of 10₆ and low bias voltage of 127V. Also the fabrication process conditions has been given.

A liquid crystal (LC) microlens with a new type of electrode pattern is designed. The both bottom and top ITO electrodes of LC microlens are placed face to face, and are separated by glass spacer with the thickness in micron scale, and then LC materials are injected into the cell constructed by them. Because of the two electrodes directly and closely facing the LC layer injected, the design can largely decrease the driving signal voltage for LC lens. The bottom electrode is designed with one round hole pattern. The top electrode is four circle patterns. The diameters of round hole and circle are 500μm and 160μm, respectively. Each circle pattern electrode can be used to focus incident light into different region over the focal plane of LC lens. When the four circle electrodes are driven by different signal at the same time, the focus can be moved off-axis over the focal plane of LC lens, and thus the voltage amplitude can be varied in the range from 0V_rms to 20V_rms. So, we realize a LC microlens with tunable-focus over the focal plane of LC lens driven by low-amplitude voltage signal.

In this study, an innovative temperature-insensitive and no adhesive package for FBG pressure sensor was designed. We presents an package construction to compensate for temperature deviation of a FBG by mechanical properties of different metal materials; the package realize no adhesive utilizing combined technique of electroless plating NI-P and electroplating NI and laser spot welding technology. On the basis of the study on the Material structural properties and the compensation principles analysis of the FBG, the finite element method is used to analysis of the feasibility of the construction and optimize the construction parameters. The results show that this compensation construction can effectively reduce the temperature sensitivity of the FBG.

In the paper, a 45 degree TFBG was fabricated in photosensitive fiber successfully using phase mask technique. The polarization-dependent loss characteristic of the TFBG was experimentally researched in the paper using a special measurement system. The measurement results showed that the 45 degree TFBG could act as a polarization possession element. Based on the 45 degree TFBG, a linearly-polarized Yb-doped fiber laser was demonstrated. The polarization-extinction ratio of the output laser is about 30 dB. The output power was about 13 mW with the pump power of 100 mW. The central wavelength of the laser is 1064nm and the wavelength bandwidth was about 0.7nm. Being a polarization device, the TFBG has the advantages of in-fiber, compact, good polarization capability and low price.

The stability for reflection-mode GaN photocathode has been investigated by monitoring the photocurrent and the spectral response at room temperature. We watch that the photocurrent of the cathode decays with time in the vacuum system, and compare the spectral response curves after activation and after degradation. The photocurrent decay mechanism for reflection-mode NEA GaN photocathode was studied by the surface model ［GaN (Mg) :Cs］:O-Cs. The reduction of the effective dipole quantity, which is caused by harmful gases, is the key factor of the photocurrent reduction.

this paper, we have prepared c-axis inclined Na_xCoO₂ thin films on 10° and 20° tilted c-Al₂O₃ substrates and studied its light-induced thermoelectric voltage effect by using an ultraviolet pulsed laser as light source. A giant open-circuit voltage signal with the peak voltage V_p of tens of voltage was observed when the film surface was illuminated by the 308 nm pulsed radiation, and the V_p increased linearly with the inclination angle as well as the laser energy on the film. In addition, we found that Ag doping in Na_xCoO₂ films can improve the sensitivity of the thermoelectric voltage signal. The results demonstrate that c-axis inclined Na_xCoO₂ thin film has a great potential application in the detection of weak ultraviolet pulsed radiation.

Based on the weakly waveguide approximation, the eigen mode field distribution of fundamental mode step index square waveguide is suggested, and the overlap integral formula between two mode field distributions is employed, the expression of coupling efficiency between fundamental mode step index square waveguide and fiber is suggested. As the values of beam propagation factors of fundamental mode step index square waveguide and fiber are closed to unit in a certain range of normalized frequency, it is rational to express the mode field distributions of fundamental mode square waveguide and fiber by the Gaussian approximation in some range of normalized frequency. As the equivalent mode field size which defined by the geometric mean of second moment mode field size and differential operator mode field size is employed to express the waist sizes of Gaussian approximation for fundamental mode step index square waveguide and fiber, the coupling characteristics between fundamental mode step index square waveguide and fiber is discussed, and a useful optimum coupling condition is suggested. The conclusions would be beneficial to the assembling technology of optical waveguide device.

In order to avoid the low sensitivity common problem of 532nm sensitive narrow-band response photocathode, variable doping narrow-band response GaAlAs photocathode structure is designed. The photocathode is composed of GaAs substrates, Ga1-x1Alx1As buffer layer, Ga1-x2Alx2As doping concentration gradient emissive layer and GaAs protection layer from bottom to top. Among them, exponential doping method is applied to Ga1-x2Alx2As unit layer from the bottom to the top. And a preparation methods of GaAlAs photocathode is developed. For the GaAlAs photocathode components which grow well, chemical cleaning, heating purification and (Cs, O) activation are operated, and ultimately Cs / O activation layer is formed on the surface of Ga1-x2Alx2As doping concentration gradient emissive layer. The highest sensitivity of the photocathode peak response is at 532nm, and the photocathode quantum efficiency in 532nm peaks at 36%.

A multimode Y-branch interconnect optical waveguide was designed and fabricated. The transmitting properties of the Y-branch splitter were designed and simulated by using commercial waveguide simulation software. For a 1×2 Y-branch splitter with 50μm×50μm channel waveguide, the relationship between insertion loss and splitting angle was calculated. According to the theoretical result, a multimode Y-branch waveguide was fabricated based on a UV-lithography method on the printed circuit board. To balance the trade-off between the insertion loss and the component size, the Y-branch waveguide was designed of two sections with different splitting angles. An insertion loss of 0.36dB was obtained theoretically with a 5cm Y-branch waveguide.

A 974 nm laser diode(LD) pumped 1120 nm ytterbium(Yb)-doped fiber laser has been experimentally demonstrated, which will be subsequently used to pump 1178 nm Raman fiber laser based on stimulated Raman scattering(SRS) effect. The resonator composes a normal single-mode Yb-doped fiber and a pair of fiber Bragg gratings(FBG). The maximum output power of 8.4 mW is achieved when the launched pump power is 183.7 mW with an optical-to-optical conversion efficiency of 4.6 %. The central wavelength is 1120.93 nm with a linewidth as narrow as 0.02 nm.

A novel polymer-modified PbS quantum dot (QD) optical fiber amplifier was proposed and demonstrated. It was fabricated by depositing a PbS QD doped film around the tapered single mode fiber (SMF) coupler. The PbS QDs were synthesized in an organic phase and then transfer into water by polymer modification. A 1550 nm semiconductor light emitting diode as the signal source and a 980 nm laser diode source as the pump were injected into the fiber coupler simultaneously. Through evanescent wave excitation, we obtained a significant gain of about 6dB within the wavelength range between 1450 and 1650 nm.

A long-distance Optical Printed Circuit Boards (OPCB) was fabricated to realize high-speed optical interconnects. The OPCB was made up of polymer optical waveguides fabricated by using ultraviolet (UV) photolithography technique. The length of OPCB is 30cm. The minimal transmission loss of the optical waveguide is approximate 5.36dB at 850 nm wavelength. Two MT-RJ optical connecters were assembled on the OPCB to realize optical coupling between optical fibers and waveguides. The dependence of coupling loss on misalignment was obtained with different offset value theoretically and experimentally. The minimal total insertion loss is only 8.06dB. With 10 gigabits-per-second (Gbps) optical transceivers as the input/output module, we tested the performance of the OPCB. The date rate of 10Gbps can be transmitted successfully.

A series-cascaded fractal topological structure of microring arrays is proposed, by introducing fractal topological structures to series-cascaded all-pass microring resonators. Its analytical model is established by the transfer matrix method. Then the characteristics of this structure are investigated by the effects of coupling coefficients and loss. Generally, there are dips with the resonator number in the transmission spectra. As the loss increases, the average intensity decreases. However, the delay becomes interesting positive and negative delays. With the ring-bus coupling coefficient decreases, the dips of the spectrum become degenerated. However, there are several delay peaks with some positive delays and the other negative ones. These kinds of multiple positive and negative delays can be developed for applications in all-optical delay lines.

A high stable wavelength-tunable fiber laser is experimentally demonstrated by using a digital-micromirror-device (DMD) processor and a polarization-maintaining erbium-doped fiber amplifier (EDFA).The electronic-addressed DMD processor is able to select and couple a waveband from of the polarization-maintaining EDFA back into the fiber ring to generate a narrow line-width laser output. The tunable fiber laser shows a line-width of 0.02nm, a tuning step of 0.08nm over the c-band and a side mode suppression ratio (SMSR) greater than 50 dB. The output power uniformity of 0.016dB is achieved by using the automatic power control (APC) system under room temperature. The center wavelength fluctuation during 1 hour is below 0.01 nm.

We demonstrate a tunable erbium-doped fiber ring laser based on an all-fiber filter. The filter consists of an optical circulator, a fiber loop mirror(FLM) and a polarizer which is spliced to a segment of polarization maintaining fiber (PMF) at the angle of 45° with respect to the fast axis of the PMF. The laser can be tuned by adjusting two polarization controllers (PC) in the laser. The tuning range can reach to 6.08nm (1553.92-1560.1nm) with side mode suppression ratio (SMSR) over 38 dB. The stability of the laser is verified at room temperature in one hour, and the power fluctuation of the laser is less than 0.5 dB.

Optical microlenses have been developed for 30 years, and thus are widely used in various application fields including imaging, optical communication, optical interconnection, sensors, and so on. Traditional optical microlenses, which are usually fabricated by common optical materials such as typical glasses or silicon materials, have generally immobile shape and fixed focal length and focus distribution over the focal plane of the lens. But it has certain limitations because of the fixed optical properties, for example, a zoom lens for a CCD or CMOS camera need a change of the focal length or the lens power achieved by mechanical movements of several individual lenses in lens system. Current research demonstrates that liquid crystal (LC) is a kind of excellent electro-optic materials, because they have relatively large electrical and optical anisotropies, and their optical properties can easily be shifted by external electric fields applied. Compared to traditional optical microlenses, the focal length of LC microlenses can be changed according to the variance of the alternating signal voltage applied over the LC microlenses. A relatively wide range adjustable and precise output voltage signal can be utilized to perform well in the controlling LC microlenses array, because the variance of focal length can be set in a relatively large range when the voltage of the signal is varied in a relatively large dynamic region. According to the above demands, a digital control device with a wide-range adjustable precise output voltage is designed and realized for LC lens.

Visible light communication (VLC) is expected to be the next generation technology of indoor wireless broadband access. In order to achieve high data transmission rates, the multiple input multiple output (MIMO) VLC is proposed to break the bandwidth limitation due to the slow response time of LED devices, as MIMO-VLC offers the potential to transmit data in parallel between multiple sources and detectors. In addition, MIMO processing removes the need for precise alignment of transmitters and receivers, if the channel matrix is known and of full rank. Therefore, MIMO provides a solution to the design of wide field-of-view (FOV) receiving device for indoor VLC system, which is expensive if traditional optical components are used. This paper demonstrates the feasibility of such FOV receiving device with an integrated small size detector array, and discusses the device properties in terms of optimal channel capacity, complexity and robustness to misalignment. A physical model is proposed for system simulation based on the single lens optical transform. The aim of this effort is to design and realize the integrated receiving device of wide FOV for LED visible light communication systems.

In this paper, a three-dimensional (3-D) relaxation method is used to model the dynamic response behavior of liquid crystal (LC) directors in LC micro-optics structures with complex patterned electrodes. The method is based on Frank- Oseen continuum elastic theory by using a vectorial representation. This method can deal with liquid crystal structures with arbitrary patterned electrodes, and it is quite computational stability. Different numerical results obtained according the method are as follows: (1) the nematic LC structures with complex patterned electrodes applied by a constant voltage signal, and (2) the nematic LC structures with different thickness of LC layer, and (3) the nematic LC structures with different signal voltage. The typical results include the distribution of LC directors in LC layers, the distribution of electric potential in LC layers, and the distribution of phase retardation. The results show that the method can be used to effectively predict the formation of disclination lines, which has a strong impact on the performance of LC micro-optics structures.

In this paper, we demonstrate the fabrication and measurement of the special nano-graphene-detectors for infrared (IR) radiation. We first transfer the graphene film with a thickness in nanometer scale onto different infrared wafer including Ge, GaAs, Si, and SiO₂. The graphene microstructures consist of the transferred graphene film over IR wafer and metal electrodes fabricated over graphene sheet utilized. Because of the special band structure, the fabricated graphene microstructures can generate a large number of electron-hole pairs in a relatively broad wavelength range including ultraviolet (UV), visible, IR, and THz wavelength. In our studies, the current-voltage relationship of the graphene microstructure fabricated, which means that certain direct voltage is applied over two metal electrodes fabricated, is measured before and after illumination graphene microstructure by IR lasers. As tested, the graphene microstructures demonstrate a high optical transmittance in several typical wavelength range mentioned above. We also research the current-voltage performance of the graphene microstructure. The typical result is as follows: when the graphene microstructure is illuminated by the laser beam of 1.1μm wavelength and 0.9W power, an inflection point and remarkable current gain can be discovered. Because of the low light absorption of graphene film, the photocurrent of the graphene microstructure is limited in about 1~3mA/W under certain voltage applied. We believe that the nanometer graphene film and semiconductor materials connected directly with graphene film already forms a kind of special energy band gap, which affect the photocurrent generation.

Micro-cavity lasers with directional emission are getting more and more attention in the optoelectronic device and application field. In this paper, we presented two kinds of micro-cavity with the limason and triangle shape cavity for the directional emission application. By using quantum cascade material, the two kinds of micro cavity lasers are compared about output emission characteristics such as the far-field patterns, light output and the threshold current. The two kinds of micro-cavity lasers show good directional emission, and the limason cavity laser can reach about 30° on the main lobe of the far-field pattern with about 4.3mW peak power and the triangle can show a large one lobe with about 110° on the one side emission pattern. From the measurement result of the threshold current of the two lasers, the cavity quality factor Q finally has been obtained.

Homoepitaxial grown InGaN/GaN p-i-n junction was deposited on GaN/Si template with AlN/GaN supperlattice as interlayer by molecular beam epitaxy. Different surface microstructure of the p-GaN was affected by the amount of Mg flux. Light-emitting diode was fabricated from the p-i-n junction. The crystal properties of InGaN/GaN p-i-n junction and the related light-emitting diode properties were investigated.

An analytical model based on interconnect parameters is presented for the analysis of thermal effects on crosstalk and performance of multi-channel optoelectronic modules. The model is accurate for computing crosstalk of interconnects used in chip packaging. In addition, model is used to determine the thermal critical frequency, f_crit, above which signals becomes severely deteriorated and can be applied in the design and packaging of optoelectronic transmitter modules for reliable data transmission.

Applying coherent detection technique to advanced modulation formats makes it possible to electronically compensate the signal impairments. A key issue for a successful deployment of coherent detection technique is the availability of cost-efficient and compact integrated receivers, which are composed of an optical 90° hybrid mixer and four photodiodes (PDs). In this work, three different types of optical hybrids are fabricated with polymer planar lightwave circuit (PLC), and hybridly integrated with four vertical backside illuminated III-V PDs. Their performances, such as the insertion loss, the transmission imbalance, the polarization dependence and the phase deviation of 90° hybrid will be discussed.

Stereo vision based 3D metrology technique is an effective approach for relatively large scale object’s 3D geometric detection. In this paper, we present a specified image capture system, which implements LVDS interface embedded CMOS sensor and CAN bus to ensure synchronous trigger and exposure. We made an error analysis for structured light vision measurement in large scale condition, based on which we built and tested the system prototype both indoor and outfield. The result shows that the system is very suitable for large scale metrology applications.

Although efficiencies of > 10% have recently been achieved in laboratory-scale organic solar cells, these competitive performance figures are yet to be translated to large active areas and geometries relevant for viable manufacturing. One of the factors hindering scale-up is a lack of knowledge of device physics at the sub-module level, particularly cell architecture, electrode geometry and current collection pathways. A more in depth understanding of how photocurrent and photovoltage extraction can be optimised over large active areas is urgently needed. Another key factor suppressing conversion efficiencies in large area cells is the relatively high sheet resistance of the transparent conducting anode - typically indium tin oxide. Hence, to replace ITO with alternative transparent conducting anodes is also a high priority on the pathway to viable module-level organic solar cells. In our paper we will focus on large area devices relevant to sub-module scales – 5 cm × 5 cm monolithic geometry. We have applied a range of experimental techniques to create a more comprehensive understanding of the true device physics that could help make large area, monolithic organic solar cells more viable. By employing this knowledge, a novel transparent anode consisting of molybdenum oxide (MoOx) and silver (Ag) is developed to replace ITO and PEDOT-free large area solar cell sub-modules, acting as both a transparent window and hole-collecting electrode. The proposed architecture and anode materials are well suited to high throughput, low cost all-solution processing.

There are two steps to obtain as small as possible fiber Bragg gratings. First, it is to taper the fiber and reduce its diameter. A subwavelength-scale microfiber (MF) is the basic element of miniature fiber devices and sub-systems. Then it is to reduce the grating length. For short fiber grating, strong refractive index modulations are necessary. Strong refractive index modulations can be obtained inducing surface corrugation by alternating layers of different materials, one of which can be air. Several techniques have been proposed for the fabrication of surface-corrugated fiber gratings, including photorefractive inscription using etching, femtosecond lasers, and focused ion beam (FIB). So far, FIB is the most flexible and powerful tool for patterning, cross- sectioning or functionalizing a subwavelength circular MF due to its small and controllable spot size and high beam current density. In past two years, a number of ultra-compact surface corrugated microfiber Bragg gratings (SCMGs) have been successfully fabricated by FIB milling. The length of FIB milled SCGMs can be as small as tens of micrometers. In addition, there are several novel proposals on SCMG including wrapping a microfiber on a microstructure rod or put a microfiber on a surface-corrugated planar grating. In this paper, we will introduce recent advances in these ultra-small SCMGs and their characteristics and applications.

This paper reports the design procedure of planar lightwave interleavers based on Echelle gratings structure, introduces two methods to eliminate the device aberration, two-point aberration-free design and elliptical grating facets design. Simulation results show that the device insertion loss and crosstalk can be effectively reduced by aberration compensation design. Design example is given in this paper. The 50/100GHz and 100/200GHz interleavers are fabricated on the SOI (Silicon-on-insulator) materials. As compared to other solutions, they are smaller and compact in structure.