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Active optical imaging is preferred over radio frequency counterparts due to its higher resolution, faster area search rate, and relatively easier learning and interpretation of the image by a human observer. However, in imaging through atmosphere, one should consider dispersive effects of multiple scatterings and turbulence-induced wave perturbations, which give rise to intensity fluctuations and wavefront distortions. All these phenomena broaden and distort the spatial impulse response known as the point spread function (PSF). In this paper, a spatially multiplexed multi-input--multi-output imaging system design, inspired by multispot diffuse indoor communications configuration first introduced by Yun and Kavehrad [IEEE International Conference Selected Topics in Wireless Communications (IEEE, 1992), pp 262-265], is presented. At the transmitter, a computer-generated holographic beam splitter is used to generate arrays of beamlets, providing a faster area search rate and a uniformly distributed illumination over the entire target area. Then, at the receiver, an array of photodetectors is used to collect the reflected rays. While a Monte Carlo ray-tracing algorithm developed at Pennsylvania State University, Center for Information and Communications Research (CICTR), is used to model imaging in multiple-scattering turbid media, phase screens are employed to simulate turbulence-induced wavefront distortions. Hence, a comprehensive framework is exploited that takes into account possible sources of degradation. Using this framework, system performance is analyzed under different meteorological conditions. Restoration techniques such as adaptive-optics corrections, blind deconvolution, and time gating are used to improve the contrast and enhance the sharpness and resolution of the images. [c] 2010 Optical Society of America OCIS codes: 110.0113, 110.0115, 110.1080, 110.1455.

To abandon restrictions from the multiple and irregular radiation patterns of many existing LED products, the free-form microlens optics is designed based on Snell's law and the 'edge-ray principle.' This secondary optics can redistribute any LED radiation onto the target surfaces to achieve prescribed uniform illuminations without concern for the initial radiation patterns of LED sources. According to practical illumination requirements, the surface shape of the single free-form microlens can be calculated by using the ray tracing method and B-spline fitting. Some modules of free-form microlens optics were constructed to achieve rectangular illumination as well as other styles of illumination. The simulation results show that the illumination achieved has high uniformities and precise illuminating shapes as prescribed. The free-form microlens optics is very applicable in LED lighting, with cogent competitive advantages. [c] 2009 Optical Society of America OCIS codes: 080.4298, 220.2945, 080.4225.

The operation of positive index-guided submicrometer-ridge laser arrays (SLAs) that produced a near-diffraction-limited single-main-lobe far-field profile (FFP) is described. The SLAs have favored the lasing of in-phase array modes and have produced a near-diffraction-limited single-main-lobe FFP.

A narrow-linewidth MgO-periodically poled lithium niobate (PPLN) optical parametric oscillator (OPO) with two volume-Bragg-grating (VBG) mirrors in a linear cavity configuration is presented. The results showed that two VBG mirrors detuned from one another by 0.456 nm have allowed obtaining most narrow linewidth.

The fast tunable optical switches and tunable slow-light devices are designed as optical cavities entangled with quantum dots. The analytical conditions for switching and tuning the filter transmittance are based on both, dipole-induced transparency and electromagnetic-induced transparency effects.

A nonlinear dynamics approach is used to study the deterministic behavior of ultrapure microwave generators, which are also referred to as optoelectronic oscillators (OEOs). The results obtained from the nonlinear dynamics approach demonstrated that the amplitude of the ultrapure microwave does not monotonously increase with the gain.

Superconductive traveling-wave photodetector devices (STWPDs) are introduced as a general platform for ultrafast, ultrasensitive and ultralow-noise optoelectronic devices.

A monolithically integrated optical receiver with voltage-controlled sensitivity in 0.6-[micro]m BiCMOS technology is presented. The transimpedance variations are achieved by varying the control voltage of the voltage-controlled resistor changing its equivalent resistance. The optical receiver design is based on a P-intrinsic-N photodiode and on a mixed current-mode and voltage-mode approach, by using a current conveyor and a voltage amplifier. Thanks to the current-mode signal processing, the bandwidth of the optical receiver is independent of the photodiode capacitance. A linearity error smaller than 2.92%, a sensitivity dynamic range of 83.2 (38.4 dB), an offset voltage smaller than 0.56 mV, a power consumption less than 4.7 mW, and a bandwidth up to 205.5 MHz are achieved. Index Terms--Current conveyor (CC), integrated P-intrinsic-N (PIN) photodiode, optical receiver, optical storage (OS) system, optoelectronic integrated circuit (OEIC), transimpedance amplifier (TIA), voltage-controlled resistor (VCR).

In this paper, a progressive design learning approach is proposed in the course of 'applied electronics' to help students to develop system design skills through an optoelectronic sensing project. This project offers a progressive guideline to lead student teams to design, build, and troubleshoot their optoelectronic systems. Such a system contains a light-source current stabilizer, a photodiode amplifier, a microcontroller system (including input and output), and optomechanical devices. In this approach, students are motivated to learn the required knowledge and skills in a future professional capacity. Those skills include designing specification, realizing teamwork and communication, and developing a variety of optoelectronic sensing techniques. Through this project, an optoelectronic sensing system is established called a spatial radiance distribution measurement system for various light sources. In particular, this kind of system is useful and important for LED industries. The course evaluations have been obtained from classmates and instructors and these results indicate that the objectives of this course are achieved. Index Terms--Microelectronics education, optoelectronic sensing technique, optoelectronics education, project-based learning.

Optoelectronic tweezers (OET) are a powerful lightbased technique for the manipulation of micro- and nanoscopic particles. In addition to an optically patterned dielectrophoresis (DEP) force, other light-induced electrokinetic and thermal effects occur in the OET device. In this paper, we present a comprehensive theoretical and experimental investigation of various fluidic, optical, and electrical effects present during OET operation. These effects include DEP, light-induced ac electroosmosis, electrothermal flow, and buoyancy-driven flow. We present finite-element modeling of these effects to establish the dominant mode for a given set of device parameters and bias conditions. These results are confirmed experimentally and present a comprehensive outline of the operational regimes of the OET device. [2007-0225] Index Terms--Dielectrophoresis (DEP), electrothermal (ET) flow, light-induced ac electroosmosis (LACE), optoelectronic tweezers (OET).

Electronic structures at the Si/Si[O.sub.2]/molecule interfaces are studied by using Kelvin probe techniques and are compared to theoretical values derived by the Helmholtz equation. The studies have shown an increase in the electronic effects on the Si substrate by increasing surface chromophoric coverage and a major consequence of depolarization is detected while comparing the experimental and calculated values.

The fabrication of a proof of concept 4 x 4 active-matrix imager at near room temperature is discussed. Results suggest the capability of the imager in correctly imaging a 'T' pattern upon calibration.

The article describes the design and fabrication of monolithic distributed balanced traveling-wave metal-semiconductor-metal photodetectors (MSM PDs) distributed along single-mode polymer optical waveguides. Findings reveal the suitability of the monolithically integrated polymer optical waveguides on a semiconductor as efficient optical interconnects in an optoelectronic circuit.

The description of a silicon-based optoelectronic device that exhibits an enhanced response to subbandgap light is discussed. Results suggest the effective response of the unutilized device to wavelengths in the range of 1480-1580 nm with an external quantum efficiency of 3.4 percent occurring at 1523 nm at an illumination intensity of 2.4 W/ [cm.sup.2].

The report discusses about the hybrid organic-inorganic optical upconverter that converts input infrared light to output visible light.

The article shows about using nonselective regrowth for monolithic integration of InP HBTs and uni-traveling-carrier photodiodes (UTC-PDs).

The performance result of a niobium photoswitch, realized on the ground plane layer of the low-Tc FLUXONICS RSFQ process which was designed, simulated and integrated with a processing RSFQ circuit is presented.

The optoacoustic transduction efficiency can be enhanced by decreasing the thickness of the black polydimethylsiloxane (PDMS) film. The center frequency and bandwidth of the generated high-frequency ultrasound can be determined by the temporal profile of the input optical pulse and it can also be improved to above 100 MHz.

A scheme for creating metal-coated vertical mirrors in silicon, along with an integrated transparent package lid for assembling, packaging, and testing microelectromechanical systems (MEMS) devices is presented. Deep reaction ion etching (DRIE) method described here reduces the loading effect and maintains a uniform etch rate resulting in highly vertical structures. A novel self-masking lithography and liftoff process was developed to ensure that the vertical mirrors undergo uniform metallization while leaving a transparent window for optical probing. Front side ofa Si wafer was shallow-etched using DRIE to define an eventual optical window. This surface was then anodically bonded to a Pyrex wafer. Backside Si was then patterned to define thin channels around the optical window. These channels were vertically etched using DRIE, after which the unattached portions of the window region were removed. Negative photoresist was spun on the remaining vertical structures and the stack was exposed from the Pyrex side using Si structures as a self-mask. Subsequent metal sputtering and liftoff results in the metallized top and mirror sidewalls while leaving a clear window. These integrated mirrors and lids are then bonded to the active MEMS mirrors. Various processes and results are illustrated with an example of packaged corner cube retroreflectors (CCRs). Index Terms--Corner cube retroreflector (CCR), microelectromechanical systems (MEMS) packaging, microoptoelectromechanical systems (MOEMS), vertical deep reaction ion etching (DRIE), vertical mirrors.

This paper presents the optimization and characterization of SU-8 quad beam optical accelerometers based on intensity modulation. An applied acceleration causes a misalignment between three waveguides, resulting in variation of losses. Mechanical simulations have focused on the evaluation of sensitivity and the design of a robust junction between the mechanical beams and the inertial mass. Results demonstrate that perfectly rounded structures show at least 4.4 times less stress than L-shaped counterparts. Optical simulation predicts that the optimal configuration in terms of sensitivity is obtained when the waveguides are not completely misaligned, since then losses are insensitive to variations in acceleration. Numerical sensitivities ranging between 11.12 and 32.14 dB/g have been obtained. Fabrication has been simplified, now requiring only two photolithographic steps and electroplating Cu as a sacrificial layer. Experimental results show a reproducible experimental sensitivity of at least 13.1 dB/g. Index Terms--Accelerometer, compliant structures, microoptoelectromechanical systems (MOEMS), polymer technology, SU-8.

An investigation on the nanostructure and photoluminescence of polycrystalline Er-doped Y2O3 thin films, deposited by radical-enhanced atomic layer deposition (ALD) is conducted. From the energy loss spectroscopy (EELS) mapping of Er in Y2O3, results reveal that Er is distributed in layers separated by layers of Y2O3 with the separation distance between the layers controlled by the ratio of Y2O3:Er2O3 cycles during the deposition.

An improved prism-based pulse shaping setup, which is capable of dealing with spectra exceeding one-octave of bandwidth is presented. The flexible tool for dispersion compensation enables us to generate the shortest pulses directly from an oscillator and these resulting pulses are almost transform-limited and show a clean temporal profile with very low background.

Wood-Rayleigh anomalies, diffraction, and electromagnetic resonance modes including horizontally oriented surface plasmas and vertical surface resonance's are identified and described. Application of these modes to metal-semiconductor-metal photo detectors (MSM-PD) is discussed.

A physical model for a superconductor-based photomixer is presented and an analytic expression for the generated photocurrent inside the superconductor film is derived. For a photo-excited superconductor film the fundamental equations for the carriers motion inside the superconductor material are used in connection with the two-temperature model to find an analytic expression for the generated tetrahertz photocurrent inside the film.

A continuous-wave tetrahertz photomixer array source made of a high-temperature superconductor material is proposed and its radiation characteristic is studied. Employing photomixer/antenna elements in an array configuration increases the available tetrahertz power.

An assembly technique is presented to realize pluggable or fully integrated optoelectronic systems based on image relays. A method to visually align and assemble optoelectronic chips or fiber bundles to half of a relay is explained. To validate this technique, two-dimensional arrays of vertical-cavity surface-emitting lasers and photodetectors and a fiber image guide have been integrated to gradient index lenses with simple optomechanical parts. Although the connection of these modules was realized with [+ or -] 0.5 mm lateral tolerances, parallel optical interconnects were successfully achieved at 10 MHz. The lateral misalignment between chips was on average 20 [micro]m and at worst 60 [micro]m. OCIS codes: 200.4650, 220.1140, 200.2610, 060.2360, 110.2760.

Bacteriorhodopsin is photochromic, crystalline and possesses chemical and thermal stability with extraordinary photosensitivity and cyclicity to illumination. As such, bacteriorhodopsin serves as a platform for designing molecular switches for optoelectronic devices and memory compaction.

The thermally irreversible photochromic compounds, diarylethenes, are remarkably fatigue resistant and as such find use in the optoelectronic devices. Data show that the aryl groups furan, thiophene, selenophene, or thiazole rings confer thermal stability to both open-and closed-ring isomers. Structural modifications of these compounds for more robust use are discussed.

A new a-SiGe:H optoelectronic hydrogen gas sensing device has been developed.

Compressively strained quantum wells are found to produce third-order optical nonlinear susceptibilities with an enhancement factor of 3 from 0.8% compressive strain, compared to nonstrained quantum wells with an equitable linear gain.

A smart-pixel array is a two-dimensional array of optoelectronic devices that combine optical inputs and outputs with electronic processing circuitry. A field-programmable smart-pixel array (FP-SPA) is a smart-pixel array capable of having its electronic functionality dynamically programmed in the field. Such devices could be used in a diverse range of applications, including optical switching, optical digital signal processing, and optical image processing. We describe the design, VLSI implementation, and applications of a first-generation FP-SPA implemented with the 0.8-mum complementary metal-oxide semiconductor-self-electro-optic effect device technology made available through the Lucent Technologies-Advanced Research Projects Agency Cooperative (Lucent/ARPA/COOP) program. We report SPICE. simulations and experimental results of two sample applications: In the first application, we configure this FP-SPA as an array of free-space optical binary switches that can be used in optical multistage networks. In the second, we configure the device as an optoelectronic transceiver for a dynamically reconfigurable free-space intelligent optical backplane called the hyperplane. We also describe the testing setup and the electrical and the optical tests that demonstrate the correct functionality of the fabricated device. Such devices have the potential to reduce significantly the need for custom design and fabrication of application-specific optoelectronic devices in the same manner that field-programmable gate arrays have largely eliminated the need for custom design and fabrication of application-specific gate arrays, except in the most demanding applications.

A method is introduced to simplify the analysis and design of microwave and optoelectronic networks such as spectral filters, interferometric sensors, etc., comprised of 2 x 2 couplers, waveguides, reflectors, and mismatched interfaces. The key element which makes it possible to reduce topological complexity and rearrange a network into a chain of cascaded four-ports, is a generalized, single-mode lumped-element 2 x 2 coupler with arbitrary coupling paths. As a result, one can now enumerate and evaluate all possible feedback-assisted and resonant configurations. The emphasis is on providing a computationally efficient method of analysis applicable to a wide variety of networks, rather than on obtaining the simplest and most transparent analytical expressions for a particular configuration. Index Terms - Filter circuits, interferometric networks, network analysis, sensors.

We demonstrate a new type of broad-band microwave phase shifter with superior performance at frequencies up to 20 GHz. This is implemented by simply adding an offset voltage prior to the loop filter (LF) in a laser-diode-based digital optoelectronic phase-locked loop (OEPLL). Accurate control of the phase of microwave signals with a continuously tunable range exceeding 640 [degrees] ([approximately]3.6[Pi]) is achieved. The phase fluctuation and long-term drift of any desired phase shift are as small as 5 [+ or -] 0.4 [degrees] and 0.08 [degrees], respectively, at 20 GHz. The relative phase instability can be maintained within 0.09 [degrees] while operating in a phase-shift-keying (PSK) scheme. We also demonstrate accurate control of relative phase difference between dual phase-locked microwave sources using the phase shifter. Our results indicate potential application of this broad-band optoelectronic phase shifter in a phased-array antenna system. Index Terms - Microwave, optoelectronic, phase shifter.

A one-dimensional 280-nm period silicon grating designed to exhibit polarization-dependent reflection or antireflection behavior at visible wavelengths has been fabricated and tested. For normally incident 575-nm light, this grating reflects less than 3% of the incident radiation polarized perpendicular to the grating grooves and approximately 23% of the orthogonal polarization. To demonstrate the grating's broadband characteristics, reflectance measurements are presented over the free-space wavelength range 475 nm < [[Lambda].sub.0] < 800 nm, for angles of incidence in the range 0 [degree] < [Theta] < 40 [degrees], for polarization parallel and perpendicular to the grating grooves, and for planes of incidence parallel and perpendicular to the grooves. A description of the fabrication process is also given.

The Y-junction structure is fundamental to optoelectronic devices, although there are inherent limitations to the conventional Y-junction structure. Several wide-angle and low-loss Y-junction structures have been reported, and the microprism-type has potential for practical application. A novel structure combining phase-front accelerator with microprisms has been proposed. Simulated results, using the fast Fourier transformation beam propagation method illustrates the structure's performance.

We present a novel algorithm for designing optimal cellular interconnects (OCI's), which can significantly accelerate the communications among processors in single-instruction multiple-data machines with optoelectronic interconnections. We present the foundations of the OCI architecture and show that the optoelectronic OCI is the optimal topology for a space-invariant interconnect pattern. The OCI is optimal in achieving a minimum number of clock cycles per data shift for a given number of optoelectronic links. In addition, our algorithm for designing the OCI is deterministic, whereas previous designs required a trial-and-error procedure.

We report on the implementation of an optical crossbar interconnect consisting of a centralized free-space beam-steering subsystem, a distributed array of vertical-cavity surface-emitting lasers and photoreceivers, a fiber image guide, and a large-core polymer fiber array. The interconnect can in principle handle more than 350 cross-bar channels, but our implementation demonstrated only 240 channels. Transmissions of 500-Mbit/s per channel were demonstrated. Approximately 12.7-dB end-to-end optical channel attenuation was measured. Details of component design, packaging, system integration, and testing are presented and discussed. OCIS codes: 060.2330, 060.4230, 160.5470, 200.4650.

The wormhole adaptive recovery-based routing via pre-emption (WARRP) core optoelectronic chip, which integrates core deadlock-handling circuitry for a fully adaptive deadlock-free multiprocessor network router, is presented. This chip demonstrates primarily the integration of complex deadlock-recovery circuitry and free-space optoelectronic input-output on a monolithic GaAs-based chip. The design and implementation of the first-generation, bit-serial, torus-connected chip that uses 1400 transistors and six light-emitting diode-photodetector pairs is presented. OCIS codes: 250.0250, 060.4250.

A concept for a parallel digital signal processor based on optical interconnections and optoelectronic VLSI circuits is presented. It is shown that the proper combination of optical communication, architecture, and algorithms allows a throughput that outperforms purely electronic solutions. The usefulness of low-level algorithms from the add-and-shift class is emphasized. These algorithms lead to fine-grain, massively parallel on-chip processor architectures with high demands for optical off-chip interconnections. A comparative performance analysis shows the superiority of a bit-serial architecture. This architecture is mapped onto an optoelectronic three-dimensional circuit, and the necessary optical interconnection scheme is specified. OCIS codes: 070.6020, 250.0250.

Advances in VLSI and optoelectronic multichip module technologies are enabling the construction of ultracompact massively parallel processing systems. The technological parameters that define the wirability and delay characteristics of these technologies have a significant impact on the system architecture. An analytical model is presented that allows the design space exploration of the interconnection networks associated with multinode chips packaged on a single multichip module substrate. Possible system designs are evaluated for a two-level interconnect with separate k-ary n-cube networks for interchip and intrachip communication. The impact of several architectural and technological parameters on the optimal network implementation (based on average no-load latency) is analyzed. OCIS codes: 050.1970, 200.4650, 250.0250.

A dot pattern of a refractive-index change was formed by spot heating with laser-beam irradiation on sodium tellurite glasses. The 15[Na.sub.2]O [multiplied by] 85Te[O.sub.2] (mol. %) glass doped with 2 mol. % of CoO was irradiated by a green light-beam spot (532 nm) [approximately]800 [[micro]meter] in diameter from the second-harmonic generator of a Q-switched pulsed YAG laser. The map of the refractive index of the glass was determined with an He-Ne laser beam by a scanning ellipsometric technique at a resolution of 100 [[micro]meter] x 50 [[micro]meter], indicating that the spots possessing a refractive index lower by [approximately]0.05 were formed at the region irradiated by the laser beam. OCIS codes: 140.3300, 160.2750, 330.5000, 120.5710.

Optical fiber telecommunication systems are being driven further into the Access network. However the cost of optoelectronic receivers and transmitters must be significantly reduced if fiber systems are to reach directly to customer premises. The active alignment stage, to couple optical fiber to the semiconductor device, is the main cost. If the output radiation pattern of the device is matched to the input radiation pattern of optical fiber, low cost passive alignment methods can be achieved.