This PDF file contains the front matter associated with SPIE Proceedings Volume 6996, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

In this work we present an analysis of the propagation, based on the Dirac equation, of spinor-electron quantum modes, that is, of spinor-electron guided waves in asymmetric 2D and 1D semiconductor nanostructures. Spinor-electron modes are calculated by means of Dirac equation in an asymmetric 2D semiconductor structures, analogous to the wellknown optical modes of the conventional integrated optics; moreover, by means of standard methods well stablished in integrated photonics, such as Marcatili method or Knox-Toulios method, 1D electron waveguides are studied. The study of these nanoelectronic devices based on electron waveguides in semiconductors is directed to understand better the possibilities of linking between nanoelectronic and nanophotonic devices.

We study 200 nm thick hydrogenated amorphous silicon (a-Si:H) optical strip waveguides fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique over PECVD silicon oxide on top of standard silicon wafer. The layer of a-Si:H is etched by Reactive Ion Etching (RIE). The ability to deposit a-Si:H at low temperatures (~250°C) by PECVD renders it a promising material for integration of optical waveguides with microelectronics. Waveguides with width varying from 2 μm to 10 μm exhibit low loss. Material refractive index data of a-Si:H is measured by reflectometry and is used in simulations. A high refractive index contrast between a-Si:H and air allows tight optical confinement of modes. We demonstrate Bragg gratings fabricated by e-beam writing technology on top of the waveguides. The period of the grating is approximately 300 nm and the depth of the grooves is about 30 nm. The grating on top of the waveguide act as mirror.

Silicon photonics is a rapidly progressing field, where silicon structures are developed for optical information generation, transmission and processing. Although substantial progress has been achieved in the fields of transmission and processing, significant challenges remain to be addressed in generating light on silicon. In this paper we show that by integrating a silicon resonator with organic semiconductors, light generation on silicon chips can be achieved in the visible spectral range. Unlike similar attempts in the telecommunication spectral region, the signal from our device can be directly measured by silicon photodetectors.

Hybrid organic-inorganic waveguides based on ZnO-(3-glycidoxypropil)trimethoxisilane (GPTS) have been fabricated by sol-gel route. A transparent sol of ZnO was added to the GPTS host and the resulting sol was deposited on silica substrates by spin coating technique. Waveguides with different molar composition (100-x)GPTS-xZnO (x=10, 20, 30) were investigated by different diagnostic techniques. Morphological measurements were carried out by means of an AFM apparatus, and a roughness of few nanometers was determinate for all the waveguides. Optical properties such as refractive index, thickness, number of propagating modes and attenuation coefficient were measured at 632.8, 543.5, 1319 and 1542 nm by the prism coupling technique as a function of the ZnO content. Photoluminescence measurements showed a large luminescence band in the region between 350 nm to 600 nm with a main peak centred at about 380 nm, due to the presence of ZnO nanoparticles.

In this work, we report theoretical and experimental results on the use of Cadmium Telluride (CdTe) doped with Zinc (Zn) as core material for the development of all-optical photonic devices. We include the design of optical waveguides for strong field confinement, technological processes to grow CdTe on 6" or 8" wafers (suitable for high-volume manufacturing) as well as the fabrication and optical characterization of optical waveguides with a CdTe core.

Different chemical processes occur in Ag exchanged sodalime glasses involving both silver and the host matrix. Aim of this study is to analyze the role of the Ag concentration in relation to the chemical state of silver in the glassy matrix. Four different sodalime glasses were analyzed using X-ray Photoelectron Spectroscopy. Strong changes of all the spectral features are observed increasing the silver concentration in the samples. These were correlated to changes of the electronic structure of Ag which reflect the structural arrangement of this element in the glassy matrix. These results were also correlated to the optical response of these glasses which are produced in view of telecom application.

We investigate circular grating resonators (CGR) with a very small footprint. Photonic devices based on circular grating resonators are computationally designed, optimized and studied in their functionality using finite difference time-domain (FDTD) method. A wide variety of critical quantities such as transmission and reflection, resonant modes, resonant frequencies, and field patterns are calculated. Due to their computational size some of these calculations have to be performed on a supercomputer (e.g. parallel Blue Gene machine). The devices are fabricated in SOI using the computational design parameters. First they are defined by electron-beam lithography. Then the pattern transfer is achieved by an inductively coupled reactive-ion etch process. Finally, the devices are characterized by coupling light from a tunable laser with a tapered lensed fiber. As predicted from the simulations the measured transmission spectra exhibit a wide range of different type of resonances with quality factors exceeding 1000.

We propose a finesse enhancement scheme by a simple two-ring system, in which the resonance finesse is dependent on the relative intensity buildup of the second ring with respect to the first. In lossless case, it is possible to obtain finesse two orders of magnitude higher than that of the single ring system. The two-ring system is fabricated in silicon-on-insulator using deep UV (DUV) lithography and shown to exhibit the finesse of 100 to 300. The associated finesse enhancement of 20 is in a good agreement with the theory.

We present a compact passive optical add-drop filter which incorporates two microring resonators and a waveguide intersection in silicon-on-insulator (SOI) technology. Such a filter is a key element for designing simple layouts of highly integrated complex optical networks-on-chip. The filter occupies an area smaller than 10μm×10μm and exhibits relatively high quality factors (up to 4000) and efficient signal dropping capabilities. In the present work, the influence of filter parameters such as the microring-resonators radii and the coupling section shape are analyzed theoretically and experimentally

Exploiting the formal analogy between the transfer function of a micro-resonator and the optical susceptibility of an atomic medium, we investigate the spectral and energetic properties of active cavities seen as mesoscopic "photonic atoms". The resemblance is not limited to linear regime; a structural equivalent can be found for such fundamental processes as spontaneous emission, stimulated absorption and emission, saturation of the active medium or induced transparency.

Quantitative experimental assessments of stress/strain with sub-micrometer spatial resolution are shown in both crystalline and amorphous structures of a metal oxide semiconductor (MOS), consisting of Si and SiO_x, respectively. A piezo-spectroscopic (PS) approach, based on the wavelength shift of a spectroscopic band in a solid in response to an applied strain or stress, has been used throughout this investigation. Although the PS behavior in such different structures obeyed completely different physical rules, its rationalization gave access to stress/strain information, regardless of the particular spectroscopic transition involved. In this paper, we applied two complementary PS analytic procedures suitable for MOS semiconductor devices: (i) using the LO Raman transition for rationalizing the stress state on the crystalline-Si side of the device; and, (ii) using the electro-stimulated spectrum of oxygen point defects for analyzing the amorphous SiO_x side of the device. As a further step, in this study, we challenged a nanometer-scale spatial resolution in stress assessments by applying spatially resolved PS procedures, which involved deconvolution of both laser and electron probes in the respective materials.

We report on the evolution of form birefringence due to thermal annealing in SiO_x/SiO₂ superlattices (SL) deposited by Plasma enhanced chemical vapor deposition (PECVD). Superlattices with layer thickness of 5 or 8 nm for both the SiO_x and SiO₂ layers were annealed at different temperatures from RT to 1150°C. Variable angle spectroscopic ellipsometry (VASE) was used to measure the negative form birefringence β and total thickness of the superlattice. The evolution of the ordinary (n₀) and extraordinary (n_e) refractive indices, the form birefringence and the thickness can be correlated with processes like sintering, phase separation in the SiO_x-layers and roughening of the SiO₂/SiO_x interface.

Optical properties of ferroelectric BaTiO₃ (BTO) and paraelectric SrTiO₃ (STO) multilayer structures were investigated as a possible material choice for thin-film electro-optic devices. It has been demonstrated that dielectric properties can be enhanced by optimizing the stacking periodicity of BTO-STO superlattices, and in this work, it was studied how the shifts in permittivity are transferred to the optical properties. BTO-STO superlattices with stacking periodicity varying between 27 Å and 1670 Å were grown on MgO substrates by pulsed laser deposition. In x-ray diffraction patterns, periodic satellite peaks were observed indicating the formation artificial superlattices. The evolution of electro-optic response with varying stacking periodicity was analyzed by ellipsometric transmission method. The electro-optic response reached a maximum at a stacking periodicity of 105 Å corresponding the individual layer thickness of 13 unit cells. The suitability of superlattices, and also single layer BTO thin films, in planar optical devices were evaluated by fabricating and characterizing Mach - Zehnder waveguide modulators.

Broad-band light-emitting color-center active waveguides induced at the surface of Lithium Fluoride, LiF, crystals by direct writing with low-energy electron beams show great potentialities for the realization of innovative miniaturized solid-state light sources, optical amplifiers and lasers operating in the green-red wavelength interval under optical pumping in the blue spectral range. Their full spectral characterization, hence the optimization of LiF-based single-mode active waveguides, still remains a difficult task. Color-center micro-strip waveguides induced by electron-beam lithography in LiF crystals were successfully characterized via fluorescence imaging microscopy and optical transmittance measurements performed in a versatile spectrophotometer that can measure the transmittance through microstructures down to dimensions of about 50 μm. The irradiation gave rise to the stable formation of primary and aggregate color centers within a thin surface layer of the crystal, whose refractive index is locally modified with respect to the surrounding blank material. The electronic defect volume concentrations and the wavelength-dependent refractive index modifications were evaluated as functions of the irradiation dose for three active micro-strips produced by 12 keV electrons on the same LiF crystal.

Doubly resonant microcavities can be used to enhance optical nonlinearities. We propose a coupled modes analysis of second-harmonic generation in cylindrical whispering gallery mode III-V microresonators. We show that microdisks can be used to obtain the quasi-phase-matching condition and that by engineering their refractive index it is possible to optimize the effective second order nonlinear polarization by maximizing the fundamental and second-harmonic mode overlap. In a second part we show that the use of side-coupled integrated spaced sequence of resonators (SCISSOR) can lead to an adaptation of the Fresnel phase-matching to the case of highly confining waveguides.

Recently, a new generation of high-resolution ultra-compact spectrometers (SWIFTS) has been investigated in integrated optics. Its principle consists of sampling an interferogram obtained by a stationary waves in an optical waveguide without moving parts. Then a Fourier transform of the interference pattern gives the spectral response of the optical source under test. The sampling is obtained thanks to metallic nanowires set upon the surface of the waveguide. Only a small part of the light, proportional to the light under the metallic element is scattered outside. Then this radiated part is detected on a camera through an optical lens. In this paper, this device is modelized using an Aperiodic Fourier Modal Method allowing simulation of a long SOI waveguide composed of very small metallic elements described by a complex refractive index. We demonstrate the possibility of obtaining the spectral response with this method. Instead of using a classical lens associated to a camera, we also modelize an entire compact device composed of a linear photo-detector array above the waveguide separated by a peculiar gap. This gap is chosen in order to image the interferogram without damaging the initial interferogram. Spectral resolution close to 4 nm is obtained with 1 mm waveguide length.

The semiconductor industry appears to be encouraging the photonic industry to make highly integrated low-cost optical systems. Planar lightwave circuit (PLC) technology is widely accepted for manufacturing photonic components and Silicon-on-insulator (SOI) waveguides have attracted much research for implementing the highly integrated PLC-based devices. In this work, starting with the guided-mode conversion process and the principle of transportation waves, we mathematically model the structure of corner mirrors of SOI waveguides with a model of effective reflecting interface (ERI). Then we simulate the transfer efficiencies with FDTD method and testify the simulation results with commercial FDTD software tool. Further, we analyze the simulation results and conclude that the conversion efficiency of a corner mirror is determined by several parameters including the geometrical structure, the index-difference of waveguide-reflector materials and the roughness of waveguide-reflector interface. For the corner structure from 90-120°, the optimal transfer efficiency can be achieved more than 98% and the access loss is less than 0.1 dB if the scattering loss of waveguide is not taken into account, but they become 95% and 0.2 dB if the scattering loss is taken into account. For some important PLC components, the deflection angle of 90-120° is good enough for implementing the compact design of highly integrated PLC-based devices.

A rigorous, full-vectorial and computationally efficient finite element-based modal solution, together with junction analysis and beam propagation approaches have been used to study bending loss, transition loss, mode coupling and polarization coupling in bent optical waveguides with vertical or slanted side walls. The waveguide offset and their widths have been optimized to reduce the transition loss and the mode beating.

In this proceeding, we present for the first time, a nested-ring Mach-Zehnder interferometer (NRMZI) on SOI (Silicon-on- insulator), realized using a CMOS based process. We show that the device operates in two propagating resonance modes: (1) The inner-loop resonant mode due to strong build-up inside the inner-ring and (2) the double Fano-resonance mode due to strong light interaction with the outer loop. The experimental data shows that the inner-loop resonance is highly sensitive to the MZI arm imbalance as compared to the double-Fano resonance mode. With such considerations, a good fit is acquired between theory and experiment.

Optical nonlinear effects have been widely studied in III-V semiconductor photonics. However, nonlinear performance in silicon photonics is still inefficient. An alternative silicon-based waveguide configuration, which is known as slot waveguide, has been recently proposed to improve the nonlinear performance in a very efficient way. In the slot waveguide, the fundamental mode light is highly confined in a very small region, which is called slot, of a low index contrast material between two silicon high index contrast layers. This enables the introduction of new silicon photonic devices in which the characteristics of active optical materials can be efficiently exploited for modulation, switching, sensing, and other applications. Horizontal and vertical slot waveguides for optimum nonlinear performance have been recently proposed. However, the horizontal slot waveguide is more feasible for nonlinear applications. To increase nonlinear performance in the horizontal slot region, silicon nanocrystals (Si-nc) embedded in silica (SiO₂) have been proposed to fill the slot region between the two silicon layers. It is achievable nonlinear performance in the horizontal slot region for down to 50nm thick slots. However, the lower the slot thickness is, the more difficult the coupling to fiber results. One of the most developed silicon photonics efficient vertical coupling techniques is the grating coupler. We demonstrate grating couplers for efficient coupling between horizontal slot waveguides and standard single mode fibers. Broadband and highly efficient horizontal slot waveguide grating couplers have been obtained by means of simulations. These grating couplers configuration are suitable for nonlinear performance in silicon photonics. It is achieved 61% maximum coupling efficiency for λ=1550 nm and TM polarization. Furthermore, a 35 nm 1dB-bandwidth is achievable for the designed grating couplers.

We present ultra-compact integrated optical echelle grating WDM (de-)multiplexers for on-chip optical networks. These devices are based on a design with two stigmatic points. The devices were fabricated using Silicon-On-Insulator (SOI) photonic waveguide technology thus the smallest version of the (de-)multiplexer occupies an area of only 250x200 μm. We will show measurement results on different variations of the echelle grating devices. In the measurements, we found a channel to channel isolation of 19 dB. The minimum insertion loss, relative to a straight waveguide, is only 3 dB with a channel to channel variation of 0.5 dB.nefit of the numerical reconstruction properties of DH in combination with diffraction grating to get super-resolution. Various attempts have been performed and results are presented and discussed. The approaches could be used for metrology and imaging application in various fields of engineering and biology.

This paper reports an accurate design of Er³⁺-Yb³⁺-Ce³⁺ doped ZrF₄-ErF₃-LaF₃-AlF₃ (ZELA) fluoride glass channel amplifier operating in the third window of the telecommunication systems. By considering measured spectroscopic and optical parameters, we demonstrate the feasibility of a novel optical waveguide amplifier exhibiting high gain and low noise figure. The electromagnetic investigation has been carried-out by employing a full-vector Finite Element Method (FEM) solver. The mode electromagnetic field, calculated at different wavelengths, constitutes the input data for the home-made numerical code which solves both the power propagation and population rate equations via a Runge-Kutta based iterative algorithm. The dependence of the up-conversion coefficients on erbium concentration are taken into account. In the simulations, the core shape, the waveguide length, the input pump and signal powers, the erbium and the ytterbium concentration are varied with the aim to optimize the amplifier performance. The goal of achieving high gain with a short device length is demonstrated. In particular, the simulation results show that the waveguide amplifier exhibits an optimal internal gain value close to 22.5 dB and a noise figure of 4.1 dB for a waveguide amplifier 5.5 cm long, an erbium concentration of N_Er=2.5×10²⁶ ions/m³, ytterbium concentration N_Yb=2.4×10²⁶ ions/m³, N_Ce=6×10²⁶ ions/m³, an input pump power P_p=100 mW and an input signal power P_s=1 μW.

We report on edge-emitting InAs/GaAs quantum dot laser promising as multiple wavelength light source for dense wavelength-division-multiplexing systems in future generation of silicon photonic integrated circuits. Broad and flat gain spectrum of quantum dots as well as pronounced gain saturation effect facilitate simultaneous lasing via a very large number of longitudinal modes with uniform intensity distribution (comb spectrum). A very broad lasing spectrum of about 75 nm in the 1.2-1.28 μm wavelength range with a total output power of 750 mW in single lateral mode regime is achieved by intentional inhomogeneous broadening of ground state transition peak and contribution of lasing via excited state transitions. Average spectral power density exceeds 10 mW/nm. A bit error rate less than 10^-13 is demonstrated for ten spectrally filtered and externally modulated at 10 Gb/s Fabry-Perot modes owing to a low (<0.3% in the 0.001-10 GHz range) relatively intensity noise of each individual mode. This result shows aptitude of a multimode quantum dot laser for high bandwidth wavelength-division-multiplexing systems.

CMOS image sensors (CIS) are becoming ubiquitous these days, but they still lack some fundamental ingredients of high-sensitivity imaging: low dark current, high quantum efficiency and high optical fill factor combined with CMOS signal-processing capabilities. Although these limitations are a nuisance in consumer products, they present fundamental limitations in industrial sensors and scientific instrumentation. It has been concluded from previous attempts to fundamentally change the behavior of CIS technologies that there is a need to drastically change the way of producing CMOS imagers. Espros Photonics Corp. has been founded in early 2007 to realize some of these concepts in order to provide a European technology platform in CMOS-integrated photonics. We will present the fundamental concepts together with specific examples as well as the potentials for users of this technology platform whose inherent goal is to reach the single-photon detection limit in CMOS image sensing.

On September 10, 2007 the Optoelectronics Industry Development Association (OIDA) formed the Silicon Photonics Alliance (SPA) Community of Interest (COI) group within the OIDA to focus on market and business cooperation by its members in order to enable silicon photonics product introduction to mainstream markets. This paper discusses recent development in commercialization of silicon photonics based products, the mission of the SPA in supporting commercialization of Silicon Photonics based products, SPA activities and benefits of joining the alliance. Finally contact information for interested parties is provided to assist in joining the alliance.

This paper presents an overview of the specific challenges that need to be overcome to make very-large CCD and CMOS imagers, and presents some recent innovations in this area. The complete development chain is described: research, production and industrialization. It will be shown that by innovative design and technology concepts, high-quality very large area CCD and CMOS imagers can be made, even up to wafer size (6" for CCD, 8" for CMOS).

We discuss our approach to monolithic integration of Germanium photodectors with CMOS electronics for high speed optical transceivers. Integration into the CMOS process and optimization of optical coupling into the devices is described, followed by a discussion on how the devices are deployed in 4×10 Gbs receiver and transmitter subsystems. We demonstrate -19 dBm optical sensitivity for a bit error rate of 1e-12. An improvement of several dB resulted from optimizing the transimpedance amplifier relative to a design that was targeted for hybrid integration with flip-chip photodetectors, in order to take advantage of the drastically reduced capacitance of the integrated photodetectors (below 20 fF). As an example of how the versatility of on-chip waveguides and integrated photodiodes can be used, we further describe how the Germanium photodetectors are deployed to obtain a fully autonomous Mach-Zehnder interferometer subsystem with built-in monitoring and control, that can be instantiated as a single cell in an IC design. A fully differential layout is implemented for optical, electro-optic and electrical components yielding very small mismatch between components and enabling control of the interferometer with a minimum penalty.

Silicon is the dominant material in the microelectronic industry and silicon photonics is rapidly gaining importance as a technological platform for a wide range of applications in telecom, and optical interconnect. It allows the implementation of many photonic functions through the use of wafer-scale technologies normally used for advanced CMOS-processing. In this paper some of the most important issues toward a practical implementation of Silicon photonics into an industrial device will be addressed: low loss waveguides, polarization handling, tunability, hitless switching. A tunable Add-Drop multiplexer has been chosen as a case study of a fully integrated device.

A new class of integrated optical waveguide structures ("TriPleX") is presented, based on low cost CMOS-compatible LPCVD processing of alternating Si₃N₄ and SiO₂ layers. The technology allows for medium and high index-contrast waveguides that exhibit low channel attenuation. In addition, TriPleX waveguides are suitable for operation at wavelengths from visible (< 500 nm) through the infra-red range (2 μm and beyond). The geometry is basically formed by a rectangular cross-section of silicon nitride (Si₃N₄) filled with and encapsulated by silicon dioxide (SiO₂). The birefringence and minimal bend radius of the waveguide are completely controlled by the geometry of the waveguide layer structures. Experiments on typical geometries show excellent characteristics for telecom wavelengths at ~1300 nm-1600 nm (channel attenuation ≤ 0.06 dB/cm, Insertion Loss (IL) ≤ 0.15 dB, Polarization Dependent Loss (PDL) ≤ 0.1 dB, Group Birefringence (B_g) << 1×10^-4, bend radius ≤ 50-100 μm).

In this work, several building blocks for high-performance all-optical switching on silicon are addressed. The FP6-PHOLOGIC approach is based on exploiting the nonlinear properties of silicon nanocrystals embedded in slot waveguides, in which propagating light is highly confined.

Research and development on silicon-based optoelectronic devices is increasing as the need for integrated optical devices is becoming more apparent. One component which has seen rapid performance improvement over the last five years has been a Ge-on-Si photodetector which can operate between 850 and 1600 nm with high quantum efficiencies and bandwidths. We have reported on three types of these detectors; normal incident illuminated p-i-n detectors, waveguide p-i-n detectors, and avalanche photodetectors (APDs). The former has achieved -14.5 dBm sensitivity at 10 Gb/s and 850 nm, which is comparable to similarly commercially packaged GaAs devices. Waveguide photodetectors have achieved bandwidths of approximately 30 GHz at 1550 nm with internal quantum efficiencies of 90%. Normal incident avalanche photodetectors operating at 1310 nm have achieved a primary responsivity of 0.54 A/W with a 3-dB bandwidth of 9GHz at a gain of 17.

A high speed and low loss silicon optical modulator based on carrier depletion has been made. It is based on carrier depletion and consists of a p-doped slit embedded in the intrinsic region of a lateral pin diode. This device has advantages such as a low capacitance and low optical insertion loss. Experimental results are reported. Using a Mach-Zehnder interferometer with 4 mm-long phase shifter, contrast ratio of 14 dB has been obtained with insertion loss of 5 dB. A 3 dB-bandwidth of 10 GHz has been measured at λ = 1.55μm. Driving electrical power is evaluated. For a 5 mm-long active region, driving power is 100 mW at a frequency of 10 GHz. A large contribution of the dissipated power comes from the 50 Ω load at the end of the device. By integrating the modulator and its driver on CMOS chip, the load value could be varied and driving power could be reduced to a few tens of mW.

Low cost, robust and efficient light sources are suitable for optical high speed communications in integrated circuits. Microdisk resonator lasers correspond to one of the most adapted solution in regard to their performances and their processing easiness. They mix low space dimension and low power consumption (threshold<50 μW). The use of dies of InP membranes bonded onto 200 mm SOI wafers allows the fabrication of a complete optical link, with an optical InP based microsource, Si waveguides and sensors for signal collection. Contacting such sources complies with the necessity of using metals - more generally optical absorbing elements - and the necessary low power consumption to stand up traditional electrical circuits. In this paper, we investigate design rules of contacts using a simple model for fast estimated results which are compared to 3D FDTD simulations. In a second part, we will discuss the coupling between a microdisk resonator and a Si waveguide. Then we will describe the fabrication of such devices with a 200mm CMOS pilot line and point out the technological induced limitations.

Amorphous Al₂O₃ is a promising host material for active integrated optical applications such as tunable rare-earth-ion-doped laser and amplifier devices. The fabrication of slab and channel waveguides has been investigated and optimized by exploiting reactive co-sputtering and ICP reactive ion etching, respectively. The Al₂O₃ layers are grown reliably and reproducibly on thermally oxidized Si-wafers at deposition rates of 2-4 nm/min. Optical loss of as-deposited planar waveguides as low as 0.11±0.05 dB/cm at 1.5-μm wavelength has been demonstrated. The channel waveguide fabrication is based on BCl₃/HBr chemistry in combination with standard photoresist and lithography processes. Upon process optimization channel waveguides with up to 600-nm etch depth, smooth side walls and optical losses as low as 0.21±0.05 dB/cm have been realized. Rare-earth-ion doping has been investigated by co-sputtering from a metallic Er target during Al₂O₃ layer growth. At the relevant dopant levels (~10²⁰ cm^-3) lifetimes of the ⁴I_13/2 level as high as 7 ms have been measured. Gain measurements have been carried out over 6.4-cm propagation length in a 700-nm-thick Er-doped Al₂O₃ waveguide. Net optical gain has been obtained over a 35-nm-wide wavelength range (1525-1560 nm) with a maximum of 4.9 dB.

The use of broadband efficient sensitizers for Er³⁺ ions relaxes the expensive conditions needed for the pump source and raises the performances of the optical amplifier. Within this context Si nanoclusters (Si-nc) in silica matrices have revealed as optimum sensitizers and open the route towards electrically pumped optical amplifiers. Up to date two have been the main limiting issues for achieving absolute optical gain, the first one is the low quantity of erbium efficiently coupled to the Si-nc while the second is the carrier absorption mechanism (CA) within the Si-nc, which generates additional losses instead of providing amplification. In this work we will present a detailed study of the optical properties of a set of samples prepared by confocal reactive magnetron co-sputtering of pure SiO₂ and Er₂O₃ targets. The material has been optimised in terms of the increasing of Er³⁺-related PL intensity and lifetime as well as the decreasing down to 3 dB/cm of the propagation losses in the rib-loaded waveguides outside the absorption peak of erbium. Our signal enhancement results show that we have been able to reduce the CA losses to less than 0.2 dB/cm at pump fluxes as high as 10²⁰ ph/cm² s. Around 25% of the optically active erbium population has been inverted through indirect excitation (pumping with a 476nm laser line), leading to internal gain coefficients of more than 1 dB/cm.

We generated 2 nJ, ~690 fs pulses with 10 MHz repetition rate from a linear cavity mode-locked Er³⁺-doped fiber laser with a fiber taper embedded in carbon nanotubes (CNTs)/polymer composite. Evanescent field out of the taper section can interact with CNTs to see saturation of absorption. With the fiber based saturable absorber this laser has simple and robust all-fiber configuration comparing to traditional linear cavity mode-locked lasers with semiconductor saturable absorbers. In addition, we have demonstrated a mode-locked ring laser, with a similar saturable absorber, by using an ion-exchanged Er³⁺-Yb³⁺-codoped planar waveguide as the gain medium.

We present a multimode longitudinal pumping scheme for integrated rare-earth doped waveguide amplifiers which allows an efficient use of low cost multimode pump sources. The scheme is based on evanescent pump light coupling from a multimode low loss waveguide, which is gradually transferred to a single mode Si-nc sensitized Er³⁺ doped active core. Population inversion is ensured along the whole amplifier length, thus overcoming the main limitation of conventional single mode pump butt-coupling in case of strongly absorbing active materials. Great flexibility in controlling the pump power intensity values within the active core is also provided. We propose this pumping scheme at 477 nm for Si-nanocluster sensitized Erbium doped waveguide amplifiers, in which top pumping by LED arrays is limited by the low pump intensity values achievable within the active region. The coupling between the multimode waveguide and the active core has been numerically studied for slab waveguide structures using a 2D split-step finite element method. Numerical simulation results, based on propagation and population-rate equations for the coupled Er³⁺/Si-nanoclusters system, show that high pump intensities are indeed achieved in the active core, ensuring good uniformity of the population inversion along the waveguide amplifier. Although longitudinal multimode pumping by high power LEDs in the visible can potentially lead to low-cost integrated amplifiers, further material optimization is required. In particular, we show that when dealing with high pump intensities, confined carrier absorption seriously affects the amplifier performance, and an optimization of both Si-nc and Er³⁺ concentrations is necessary.

A review will be presented of recent work on Si/SiGe heavy-hole to heavy-hole quantum cascade emitters showing progress towards a laser using the bound-to-continuum design for the active region. The sample was grown by low energy plasma enhanced chemical vapour deposition in significantly less time than comparable structures and designs in III-V or Si/SiGe technology using molecular beam epitaxy or more standard chemical vapour deposition techniques. Clear intersubband electroluminescence is demonstrated at 4.2 K between 6.7 and 10.1 THz. This is inside the III-V restrahlung band where III-V materials cannot lase, unlike Group IV materials. A review of waveguide losses will also be presented and some ideas of how to design an active region with gain higher than the waveguide losses will be discussed.

Progress and take-up of photonic integration is hampered by a too large variety in devices and technologies. Generic integration platforms, which support a broad range of applications and can be made accessible through foundries, can deliver the cost reduction needed for a broader take-up. Silicon is ideally suited as such a generic integration platform and can support large-scale photonic integrated circuits. The ePIXnet Silicon Photonics Platform was set up to offer access to high-end silicon facilities for research and prototyping and to help establish photonic foundry processes on the longer term, bridging the gap between research and the market.

We present a tool for the simulation of active and passive photonic integrated circuits (PIC) based on EME (eigenmode expansion) for modelling the details of circuit elements plus the travelling wave time domain (TWTD) technique for connecting the circuit together and modelling non-linear elements such as SOAs. We show how the two algorithms can be linked together using FIR filters to create a highly efficient PIC simulator. We discuss the strengths and weaknesses of the approach and illustrate it with the simulation of a variety of active and passive examples.

We propose a scheme based on two-ring resonator system that can realize flat delay and transmission response with delay-bandwidth product (DBP) higher that those achieved in previously proposed schemes. The spectrum flatness and DBP are two key parameters that characterize the maximum number of bits that can be buffered without distortion for certain signal operating bandwidth. Simple time domain simulation shows that our scheme can achieve the same buffering time with 2 to 4 times smaller number of modules, which indicates DBP of 2 to 4 times larger than those of side-coupled ring structure and coupled resonator optical.

Communication between processors and memories has always been a limiting factor in making efficient computing architectures with large processor counts. Reconfigurable interconnection networks can help in this respect, since they can adapt the interconnect to the changing communication requirements imposed by the running application, and optical technology and photonic integration allow for an easy implementation of such adaptable systems. In this paper, we present a proposed reconfigurable interconnection network in the context of distributed shared-memory multiprocessors. We show through full-system simulation of benchmark executions that the proposed system architecture can provide a significant speedup for shared-memory machines, even when physical limitations due to low-cost optical components are introduced. We propose then a reconfigurable optical interconnect implementation, making use of tunable sources and a selective broadcasting component, and we report on the first fabricated optical components of the design: refractive microlenses, fiber connectors, microprism holders and alignment plates.

The analysis of a subcarrier multiplexing free space optical transmission system with ASK electrical modulation is presented in this paper. The designed system based on SCM-ASK-FSO allows the optimized exploration of the available spectral frequency bandwidth. The performance for the SCM - FSO subsystem obtained using ASK electrical modulation was evaluated in terms of eye diagram and bit error rate. It was verified that the FSO channel does not generate intermodulation between the subcarriers, allowing a uniform interchannel spacing. The necessity of the channel insertion was evaluated as a function of the reduction in the distance between the system transceivers. SCM techniques integrated to a FSO system operating at 1550 nm were simulated with the commercial software Optisystems from Optiwave, Inc.

A novel integrated optical device based on electrooptical control of Bragg gratings has been developed and fabricated. The device provides a possibility of a versatile control of the grating spectral transfer function and can be used as a dynamically recofigurable spectral encoder/decoder for OCDMA networks. Electrooptical control of the device ensures a high speed of dynamic reconfiguration (switching between codes) that can be used not only for the multiplexing of different channels in a network but for modulation of optical signals in the channels with information content and for development of new modulation formats.

This paper presents a magnetooptical way to reduce the modal birefringence of planar waveguides, which is a critical point for applications. Indeed, composite material, made of Cobalt ferrite (CoFe₂O₄) nanoparticles embedded in a silica/zirconia matrix by the sol-gel method, are used to develop a phase matched magnetooptic planar waveguides. Such thin composite films coated on a pyrex slide using the dip-coating technique were studied. They were submitted to a UV-treatment, under an applied magnetic field. Two techniques were used to characterize these thin films: M-lines spectroscopy and Ellipsometry. Results show the dependence of the modal birefringence ΔN value as well as the TE-TM phase mismatch on the magnetic field orientation (in plane or out of plane) applied during the UV exposure phase. They prove that a phase match is achieved on a waveguide having a 1,5 refractive index and 1,8 μm of thickness, at 820 nm. Interpretations of these results, due to a linear permanent anisotropy led by the nanoparticles orientation in the film, are given.

We discuss properties of line defect waveguides in planar photonic crystals with a triangular lattice of ring shaped holes (RPhCWs). We introduce slow-light RPhCWs with tailored dispersion properties and a compact and efficient coupler to efficiently inject light into such slow-light waveguide sandwiched between strip waveguides. We will also discuss the potential application of the RPhCW in biomedical applications and show experimental results on the RPhCW fabricated on the silicon-on-insulator substrate.

Results of the Discrete Layer Peeling (DLP) inverse scattering algorithm do not directly correspond to Bragg grating's technological parameters. We propose a method of transforming a stack of discrete complex reflectors resulting from DLP into physical and geometrical parameters of a Bragg grating suitable for fabrication in planar technology. Particularly, the method keeps lengths of grating sections (teeth and grooves) above a required technological minimum. While the stack of complex reflectors is a natural output DLP, it can also be computed from a space distribution of the complex coupling coefficient determined in other ways.

In this work is presented a macroscopic quantum-mechanical analysis of quantum light progression in different kinds of integrated photonic waveguide structures with coupled modes, and therefore with validity, for instance, for integrated optical waveguides (conventional integrated optics), photonic crystal waveguides, nano-optical waveguides (plasmonic modes) and so on. The main goal of the work is to give a consistent and explicit derivation of the quantum Momentum operator, and therefore to calculate the corresponding Heisenberg's Equations. Quantum propagation of nonclassical light states are analyzed in different linear and nonlinear integrated devices.

Polymers are increasingly attractive for the creation of optical integrated circuits particularly owing to a high thermo-optical coefficient (-10^-4 °C^-1) which allows to design optical functions tunable according to temperature. For example, tunable filters or multiplexers are attractive in telecom applications for bringing broadband services to subscribers. Moreover, the large available range of refractive index, leads to large scale of integration, lowering the fabrication costs and could be an alternative solution to semiconductor or inorganic dielectric technologies. In this work, optical functions were created using standard photolithography and Reactive Ion Etching (RIE). Photolithography was used with particular conditions to improve pattern resolution. Firstly, the details of making optical polymer waveguides and wavelength micro-ring based filters are given. Optical loss measurements of waveguides and optical characterisation of micro-ring resonators are also shown for which the results are in agreement with the modelling. Secondly, the same micro-ring resonators were observed with the temperature change and we noticed that the variation of resonance wavelength is about 0.2 nm.°C^-1. This is just what is needed for the creation of tunable filters or multiplexers without electrical high power, considering the very small size of the component.

An integrated ratiometric wavelength monitor is proposed and designed, which consists of a Y-branch and two directional couplers acting as edge filters with opposite spectral responses. With a local supermodes solution, the optimal separation distance between two waveguides and the interaction length of the directional coupler are obtained to meet the desired spectral response with significantly less computation time by comparison to a parameter-space scanning method. The wavelength discrimination ability of the designed ratiometric structure is demonstrated numerically.

The radiation loss in the whispering gallery resonators causes the eigenvalues of the Maxwell equations with the corresponding boundary conditions complex. The corresponding operators are nonhermitian and for these operators the standard perturbation techniques have some difficulties. In this paper by employing the Floquet theorem a new technique for the φ periodic perturbations is developed. The method is applied to obtain the change of resonance frequencies and losses of φ -perturbed microresonators with cylindrical symmetry. The results are compatible with that are obtained by the Volume Current Method.

Studies considering different modulation techniques used in the integration of subcarrier multiplexing (SCM) optical transmission systems are presented in this paper. The analysis of SCM systems operating in the 1550 nm signal wavelength range involves ASK, QPSK, 16QAM and 64QAM electrical modulations. From experimental results and by numerical simulation, the frequency response of the fibre for the ODSB and OSSB systems is obtained. The simulated results suggest that using dispersion compensating fibre (DCF) it is possible to compensate the dispersive effect in optical fibre for ODSB signals, allowing the system to get OSSB similar frequency response. SCM systems simulations were performed using the commercial software Optisystems from Optiwave, Inc. The system bandwidth increase was analysed in terms of fibre length and dispersion considering different links, subcarrier spacing and number of subcarriers. From experimental results, the intermodulation effect, generated by the optical fibre, is verified and indicated the necessity of using unequal spacing between the subcarriers, which is a factor that limits the SCM systems' performance.

This paper a simple semi-analytical model for calculation of the time evolution and spatial variation of the electric field in microring resonators in the presence of The Kerr effect and two-photon absorption (TPA) is presented. The theoretical analysis is based on the delayed feedback model, which is well known in microring theory. The model is applied to the Chalcogenide glass and AlGaAs microrings to study the Kerr and TPA effects on the spatial and temporal variation of electric field respectively across the microring. The effects of microring parameters and input signal shapes on the transient behavior are taken into consideration. It is shown that, the results are in good agreement with the full numerical method.

One dimensional periodic and non-periodic silicon photonic structures have been designed and fabricated on silicon-on-insulator substrate for the investigation of the electro-tuning effect in composite system Photonic Crystal - Liquid Crystal. The reflection spectra registered for non-periodic structures demonstrate the phase polarisation shift for bands of high reflection, while for the periodic structure the shift of the photonic band gap edge was observed. Under an applied electric field in the range from 2V to 10V, the shift of the polarised reflection spectra, caused by reorientation of the LC director from planar to homeotropic alignment, has been obtained. A significant change in the refractive index close to Δn=0.2, which is a characteristic feature for LC E7, has been achieved due to LC reorientation in all structures just after LC infiltration. It was found that after switching-off the applied electric field the initial planar orientation of LC molecules is not restored. This effect is related to weak anchoring of LC molecules to the silicon side-walls which results in the transition of LC to the pseudo-isotropic alignment after the applied voltage is off. A relatively smaller (with Δn=0.07), but highly reproducible electro-tuning effect was revealed during the LC reorientation from pseudo-isotropic to homeotropic alignment. The shift of the edge of PBG by Δλ=0.16 or by Δλ/λ=1.6% in relative shift units was observed in this case. The response time estimated under applied square shaped ac pulses of various frequencies was found to be around 30 ms.