The device specifications for an all optical bit-parallel WDM single fiber link for the cluster computer network community are intended for dissemination to the opto- electronic device research community to stimulate synergy between the two, ultimately leading to early availability of new devices to the computer network researchers. It is also hoped that early adoption of these devices by the research community will promote limited production of these devices by industry. Background information on our investigation of this problem will first be given. Then the detailed design of a long distance all optical bit-parallel WDM single-fiber link with 12 bit-parallel channels having 1 Gbytes/sec capacity is given. The speed-distance product for this link is 32 Gbytes/sec-km. Means to improve this speed-distance product using the pulse shepherding effect will be described. Finally, a detailed description of the BP-WDM component requirements is given.

The US government has tried to help high-tech start-ups with subsidy programs, the largest being Small Business Innovation Research (SBIR). Despite spending about $6 billion, there is scant evidence that it had any economic effect. That is, the US high-tech economy would have advanced as it has without any subsidy. Program evaluation by the government has avoided the hard questions and the programs continue undiminished. Only two bright spots have appeared, both in the Department of Defense, wherein new technology in young companies has apparently been substantially helped by SBIR. Only three startup firms in the 80s can be held up as examples of SBIR investment leading to public shareholding in the 90s. SPIE companies can expect continued subsidy from which they can gather development funds at the risk of becoming addicted to investment that demands no market discipline. Keywords: start-up company, government subsidy, SBIR ATP, new technology, evaluation

This paper shows basic concepts for the application and integration of arrayed waveguide grating multiplexers (AWGM) in larger network topologies. Stations are directly connected the AWGM in a physical star topology. The architecture offers the possibility to evolve from unidirectional logical ring structures to a fully meshed interconnection. The number of input and output ports of the AWGM has to be a prime number in order to avoid subrings that do not connect all stations. Several possible topologies to incorporate AWGM into multihop networks are considered. A new multihop architecture in the shape of a soccer ball is proposed.

An eight-channel dense wavelength division multiplexing (DWDM) system has been constructed and tested for applications to video, audio, and data transmission. The system uses DFB laser sources with wavelengths separated by 200 GHz and centered around the 1550 nm silica fiber transmission window. After transmission through the fiber, the demultiplexing of the signal requires that the optical wavelengths be separated while maintaining high isolation between channels, preferably with low insertion loss. Eight- channel DWDM demulitplexers are currently available with better than 20 dB isolation using one of several different approaches: planar arrayed waveguide gratings, bulk optical gratings, and multiple dielectric filters. For this system we are using a planar arrayed waveguide grating DWDM demultiplexer based on integrated optics fabrication techniques. The optical insertion loss ranged from 5 to 7 dB. Individual laser wavelengths were tuned to each respective demultiplexer channel by temperature tuning of the DFB laser. The overall system design requires that each wavelength carry 10 uncompressed video channel sat 8-bit coding, or 8 video channels of 10-bit coding. The data transmission rate is currently 1.2 Gbit/s per wavelength for an effective bandwidth of 9.6 Gbit/s. Results from our testing have shown channel separation of 1.6 nm with an isolation exceeding 30 dB. Bit error rates are less than 10^-12 per wavelength channel. With 8-bit video, a total of 80 channels can be transmitted simultaneously with this approach. We conclude that a system of this design is well suited for the simultaneous transmission of multi- channel video, audio, and data, and will be a very appropriate system for multi-media applications. The system is also scaleable to even higher bit rates per wavelength and to a larger number of wavelengths. Thus, systems carrying more than 1000 uncompressed video channels simultaneously appear feasible.

In this paper, we propose and demonstrate a novel compact optical cross point switch configuration using electrical current tuning. The device is made on InP/InGaAsP material. It has a digital switching characteristics, a switching current of 40 mA and switching speed of nanosecond. For NxN switches, only N electrodes are needed. The switching electrode is only 600-micrometers long. It has a cross-talk of -40 dB.

Volume photorefractive optical interconnect elements (V- POIEs) which operate at approximately 850 nm are being designed for integration into a low power, optoelectronic integrated circuit architecture. When a tunable laser is integrated with the V-POIE crystal, a photonic random optical memory access system may be developed for wavelength division multiplexing and volume holographic storage applications. The insertion of V-POIE technology will allow interconnect patterns to be stored at approximately 0.1 nm wavelength intervals and will provide wavelength selective interconnect reconfigurability at system clock speeds.

This paper describes the development and testing of a 4 channel, 10 Gbps/channel WDM module. This model incorporates four DFB lasers whose wavelengths are spaced 1.6 nm apart within the 1550 nm fiber window. A driver circuit have been developed based on a commercially-available monolithic amplifier which provides high-speed operation at low cost. The performance of the module was measured at 10 Gbps and 2.5 Gbps. Time-domain performance and crosstalk results are presented.

A method of propagation functions and transfer amplitudes suitable for the design of integrated optical circuits is presented. The method is based on vectorial formulation of electrodynamics: the distributions and propagation of electromagnetic fields in optical circuits is described by equivalent surface sources. This approach permits a division of complex optical waveguide structures into sets of primitive blocks and to separately calculate the transfer function and the transfer amplitude for each block. The transfer amplitude of the entire optical system is represented by a convolution of transfer amplitudes of its primitive blocks. The eigenvalues and eigenfunctions of arbitrary waveguide structure are obtained in the WKB approximation and compared with other methods. The general approach is illustrated with the transfer amplitude calculations for Dragone's star coupler and router.

Optoelectronic components and lightwave systems continue to rapidly advance in capabilities and complexity. CAD tools must also advance to meet the needs of the advanced lightwave systems of tomorrow. As integrated CAD tools are available for the hierarchical design of electronics systems, CAD tools for optoelectronics and lightwave systems must also offer designers an integrated, hierarchical design environment in which to effectively and efficiently design complex optoelectronic components and systems which employ them. LaserLab, Maskerade, and iFROST are examples of advanced CAD tools for optoelectronic component and lightwave systems design which are designed for use in such an integrated hierarchical design environment. LaserLab is used for material, device, and component design, simulation, and analysis. Maskerade is used for hierarchical mask layout of photonic integrated circuits with efficient treatment of the non-Manhattan geometries present in such circuits. iFROST is used for mixed-level waveform simulation of lightwave systems and can be used to analyze eye diagrams and the BER of such systems.

A novel method of interconnecting high-performance computers, predicated on the bit-parallel transmission of data, using monolithic, mode-locked WDM array sources, ten wavelengths wide, operating at greater than 20 GHz, is being developed. The byte-wide data is coupled to a single-mode fiber of appropriate dispersion characteristics, and the byte synchronism is maintained by means of a 'shepherd soliton'. The shepherding condition requires that the photonic components between the WDM array and the single- mode fiber, not introduce any skew which cannot be corrected by the shepherd soliton. This requires that the passive component skew be within the capture range of the shepherd pulse. In this paper we describe the impact of the shepherding condition on the design of the passive WDM components, and we describe a suitable coupler design, based on planar lightwave circuits and the corresponding planar lightwave circuit design rules.

High-end printed circuit board manufacturing technology is receiving increasing attention due to higher functionality in smaller form factors. This is evident from the industry efforts to produced reliable microvias and related trace features to pack as much circuit density as possible. Cost, density and performance requirements have prodded entry into a market that was mainly reserved for ceramic and molded packages for the last forty years. To successfully meet the demanding specifications of this market segment, a worldwide effort is underway for the development of new materials, processes and equipment. A novel base technology that is applicable to most of the major packaging and redistribution elements in an electronic module is presented.High density multilayer circuits with landless blind and buried vias can be fabricated by filling the conductor paste into photoimaged dielectrics and thermally processing it at a relatively lower temperature. Via layers are prepared directly on the inherently planarized circuit layer in an identical fashion. Because these composite materials are applied in an additive fabrication method, metal substrates can be employed for high thermal dissipation and excellent CTE control over a wide temperature range. The conductor material is based on interpenetrating polymer and metal networks that are formed in situ from metal particles and a thermosetting flux/binder. The metal network is formed when the alloy particles melt and react with adjacent high melting point metal particle. Interaction also occurs between the alloy particles and pad, lead or previous trace metallizations provided they are solderable by alloys of tin. The new alloy composition created by the interdiffusion process within the bulk material has a higher melting point than the original alloy and thus solidifies immediately upon formation. This metallurgical reaction, known as transient liquid phase sintering, is facilitated by the polymer mixture. INtegration of the polymer and metal networks is maintained by utilizing a thermosetting polymer system that cures simultaneously with the metallurgical reaction. Although similar in concept and performance to cermet inks, these compositions differ in that their process temperatures are compatible with conventional printed wiring board materials and that the polymeric binder remains to provide adhesion and fatigue resistance to the metallurgical network.

To support a reliable transmission in higher rate optical transmission networks this paper suggests an efficient method of test management in the transmission system or network. This test management function supports the synchronous transmission network on the basis of the fault cause and the position detection, and the exact performance information of the transmission path to be based on the path pursuit, it will enhance the effective fault localization, recovery and the survivability of the transmission network. It test signals by generating Pseudo Random Binary Signals, transmitting, receiving and automatically detecting the discontinuity and degradation of the signal via multiplexing, add/drop, and cross-connection functional modules of the equipment between the end-o-end points in the transmission network. These test methods localize faults in the equipment, connections which have not been completed, or misconnections of the paths. Also, this paper suggests an efficient fault location detecting methods by using supervisory channel in optical transmission line like WDM.

Unlike InP-based systems for long-distance communication applications, GaAs-based optoelectronic systems mostly for local-area network, optical interconnection or optical computing are very cost-sensitive because often these optoelectronic devices constitute most of the cost for these applications and fewer users share the cost. Thus besides technical issues, the processing cost should be addressed in the selection of materials and fabrication methods. We discuss a number of major advantages of Al-free InGaAsP/GaAs lasers for these applications, such as not coating- requirement, low cost, high long-term reliability, high performance. We discuss recent preliminary results of Al- free lasers as a first step toward these optoelectronic applications.

Vertical-cavity surface-emitting lasers (VCSELs) emitting in the 1530-1565 nm region of flat gain in Er-doped fibers offer the potential for low-cost transmitters for wavelength division multiplexing (WDM). Methods are described to produce precisely-defined vertical-cavity surface-emitting laser arrays which: 1) efficiently utilize wafer real estate; 2) have precise and uniform wavelength distributions despite wafer thickness nonuniformity and wafer-to-wafer thickness variation; 3) are compatible with known multiplexing technologies; 4) have minimum wavelength variation with temperature. Epitaxial growth on patterned substrates with varying-size mesas has been shown to produce multiple-wavelength VCSEL arrays by Iga's group at the Tokyo Institute of Technology. This can be combined with additional refinements to fine tune the wavelengths, increase yield, and to maximize VCSEL efficiency, manufacturability and performance. Multi-wavelength VCSEL arrays represent a much lower cost, more controllable alternative to distributed-feedback laser arrays for WDM sources. The difference in laser output powers can be largely compensated via use of an Er-doped fiber amplifier within the transmitter. Reports such as that by ElectroniCast point to transmitters and receivers as being the most vital WDM components, in terms of both cost and technology.

Foster-Miller is developing a family of low cost active WDM components based on electronically switchable Bragg gratings (ESBG) in holographically polymerized polymer dispersed liquid crystal. These provide approximately 50 microsecond(s) switching speeds, adequate for many network reconfiguration functions.Space switches, wavelength selective add-drop multiplexers, attenuators and switchable taps may be integrated in a variety of architectures on chip by using ESBGs with different periods and device geometries. ESBG fabrication is a one step, low cost process compatible with standard silicon optical waveguide techniques.

In order to lower the cost of optoelectronic packaging, a novel solvent bonding technique has been developed to bond two thermoplastic surfaces, permanently, with a room- temperature cure of approximately 30 seconds. This technique has been applied to a pigtailed PIN module with a canted fiber. As model has been developed as a design tool to simulate the responsivity and the optical back reflection of various configurations of different angled fibers and canted angles with respect to the PIN detector. Close agreement between simulations and measurements of responsivity and optical back reflection has been achieved. With this design tool, a low cost pigtailed PIN module utilizing a novel solvent bonding technique has been developed to meet CATV applications.

An advanced polymeric waveguide technology was developed for affordable WDM components that address the needs of both the Telecom and the Datacom industries. We engineered high- performance organic polymers that can be readily made into both multimode and single-mode optical waveguide structures of controlled numerical aperture and geometry. These materials are formed from highly-crosslinked acrylate monomers with specific linkages that determine properties such as flexibility, toughness, loss, and environmental stability. These monomers are intermiscible, providing for precise adjustment of the refractive index from 1.3 to 1.6. In polymer form, they exhibit state-of-the-art loss values, high thermal stability, high humidity resistance, low dispersion and low birefringence. Waveguides are formed photolithographically, with the liquid monomer mixture polymerizing upon illumination in the UV via either mask exposure or laser direct writing. A wide range of rigid and flexible substrates can be used, including glass, quartz, oxidized silicon, glass-filled epoxy printed circuit board substrate, and flexible polyimide film. Waveguiding structures measuring tens of inches in length can be produced on computer boards, and guides that are meters long can be printed on rolls of plastic. We describe the fabrication of both Bragg gratings and waveguide grating routes in our polymers for filtering and demultiplexing applications in Telecom WDM systems. In Datacom, we describe polymeric components that we produced for aerospace WDM sensor systems. The importance of CAD tools in designing WDM devices is emphasized in this work. We further discuss the low-cost manufacturing of WDM components in an industrial environment.

Using molecular beam epitaxy (MBE) and lattice engineering techniques, the feasibility of combining photonic devices applicable to the 1.3 to 1.55 micrometers wavelength range and monolithic microwave integrated circuits (MMICs) on GaAs is demonstrated. A key factor in the MBE growth is incorporation of an InGaAs active layer having an indium arsenide mole fraction of 0.35 or greater and its lattice compatibility with the underlying semi-insulating GaAs substrate. The InGaAs layer used for the photonic devices, can also serve as the active channel for the high electron mobility transistors for application in MMICs. Several examples of active and passive photonic devices grown by MBE are presented including an optical ridge waveguide, and a photodetector for detection of light in the 1.3 $mUm range. The material structure includes a 3-layer AlGaAs/GaAs/AlGaAs optical waveguide and a thin InGaAs absorbing layer situated directly above the optical waveguide. Metal-semiconductor- metal (MSM) photodetectors are formed on the top surface of the InGaAs layer for collection of the photo-induced carriers. The optical ridge waveguide is designed for lateral incidence of the light to enhance the MSM photodetector responsivity. Initial measurements on the optical waveguide and photodetector are presented.

We report on AVE's research on a new family of smart analog vision chips and ancillary software capable to adaptively select image processing parameters and regions of interest int he field of view. The project aims to adapt the wedge- and-strip (WS) position-sensitive configuration to real- time, multi-object detection. To that end, we use semiconductor WS detector (WESD) arrays with spatial prefiltering implemented via image algebra. The WESD have the ability to locate the centroid of an incident light spot and, with appropriate prefiltering, to locate the centroids of multiple light spots. A unique analog mode centroid computation scheme facilitates on-chip data processing, while an overall undemanding geometry simplify electronics fabrication. Based on results of preliminary design and analysis, very significant cost reductions over existing massively parallel vision processors ar foreseen. Superior optical resolution results even when the sensor is manufactured with 'coarse line width' semiconductor processing technology, which may lead to detectors with large photosensitive areas. Departing from photosensitive element miniaturization provides the opportunity to launch a new class of vision chips, with active area limited only by the semiconductor wafer size used to manufacture the array. We suggest several applications of this new technology, including an efficient and robust WDM demultiplexing device.

Realization of microelectromechanically wavelength tunable Fabry-Perot filters using high index-contrast distributed Bragg reflectors (DBRs) comprising GaAlAs/AlO_x and Si/SiO₂ material system are reported. Due to the broadband nature of these high index-contrast DBRs, the 3dB transmission bandwidth of the cavity resonance is narrow and stable over the tuning range. While the three different sets of GaAlAs/AlO_x based filters with different number of DBRs exhibited linewidths of 0.5nm, 2.0nm and 0.47nm with tuning ranges of 59nm, 83nm, and 60nm respectively, the silicon-based filter exhibited a linewidth of 0.3nm and a tuning range of 12nm. Transmission spectra from these devices displayed varying magnitudes of higher order spatial modes were attributed to lensing effect caused by partially oxidized AlGaAs layers within the mirror layers. One of the GaAlAs filters showed a frequency response of 500 KHz at 3dB cutoff point indicating a switching time of 2 microseconds.

We report a four channel integrated wavelength division multiplexer (WDM) and demultiplexer (WDDM) based on volume holographic gratings and substrate-guided waves at near IR wavelengths. The four operating wavelengths are centered at 750, 780, 810 and 840 nm respectively. The WDM and WDDm are demonstrated using 50/125 multimode fibers. The channel-to- channel crosstalk level is measured to be less than -40 dB. The system insertion losses are -23dB, -21dB, -22dB respectively for 750 nm, 780 nm, 810 nm and 840 nm.

A 2D wavelength-division demultiplexing device is demonstrated to separate and to distribute optical signals of different wavelengths by use of substrate-guided wave optical interconnects. In our experiment, two stacked input holographic gratings are fabricated to steer two optical wavelengths into two different routing directions and to zigzag within a waveguiding substrate. Input coupling efficiencies of 70 percent and 76 percent are experimentally confirmed at the input wavelengths of 780 nm and 790 nm, respectively. Two arrays of 1-to-10 cascaded output holographic grating couplers are employed to couple out the optical signals with surface-normal fanouts. The crosstalk is measured to be < -30 dB. The fanout energy fluctuation is within +/- 10 percent for each wavelength.

Ann add/drop multiplexer/demultiplexer using volumetric holographic crystal Bragg gratings and without use of circulators has been demonstrated. Multiplexed gratings with angle multiplexed reflection filters provide wavelength- selective reflection of one or more channels into or out of the fiber without disturbing the through channels. Overall channel add/drop losses of less than 3 dB and through channel losses of less than 0.5 dB have been demonstrated. Fabrication of holographic filters with the desired passband characteristics has also been demonstrated.

Recently Ortel Corporation won a major contract to manufacture wavelength division multiplexing optical transmitters. A number of interesting design and manufacturing issues unique to the program will be discussed.

Real-time multi-object detection has been an elusive goal of automated target recognition (ATR) scenarios that employ on- board millimeter-scale processors at low light levels and reduced power requirements. This paper discusses an adaptation of the wedge-and -strip anode to yield design analyses for a silicon wedge-and-strip detector (WESD). In practice, a WESD could compute the centroid of an incident light-spot and, with appropriate prefiltering can locate centroids of multiple light-spots. Due to on-chip processing and a nondemanding geometry, the WESD approach drastically reduces electronics fabrication complexity and cost. Based on results of preliminary design and analysis, significant cost reductions over existing massively parallel vision processors (MPVPs) are foreseen for object location via centroid computation. Algorithms and simulations are expressed in image algebra, a rigorous, concise, computationally complete notation that unifies linear and nonlinear mathematics in the image domain. Developed at University of Florida over the past decade, image algebra is a unifying language for image and signal processing that has been implemented on numerous workstations and parallel computers. Thus, our algorithms are rigorous and widely portable. Circuit analysis emphasizes effects of capacitance and electrode configuration on WESD spatial resolution. Simulation results show that the WESD has centroid computation accuracy comparable to equivalent-resolution array detectors supported by on-board MPVPs. Additional technical discussion pertains to the feasibility of space- division multiplexing for multi-object detection and location at video rates.