Alexandra K. Wettlaufer (Faux Titre, 236) Rodopi Amsterdam — New York 2003 310 pp Pb $71.00 € 60.00

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 +/-0.5 mm lateral tolerances, parallel optical interconnects were successfully achieved at 10 MHz. The lateral misalignment between chips was on average 20 microm and at worst 60 microm.

A simple assembly technique that makes use of a machine vision system is proposed to build alignment -free optoelectronic systems. It does not require any alignment marks neither on the optics or the optoelectronic chips.

Optical interconnections and integrated optoelectronic devices are expected to be promising candidates that expand interconnection bandwidth between large-scale integrated circuits (LSIs). We have constructed an optoelectronic parallel computing system that has a reconfigurable free-space parallel optical interconnection module called OCULAR-II. It has a multi-layer architecture that eliminates the data transfer bottleneck between optoelectronic processing modules by reconfigurable free-space optical interconnections. An optoelectronic processing module is composed of a two-dimensional processing element array where each pixel has its own optical output channel by a VCSEL and optical input channel. The optical interconnection is integrated into a compact module where an optically addressable phase only spatial light modulator and an imaging optical system are compactly fabricated. Each component of the OCULAR-II system has been designed to be modular and compact. Therefore, just cascading optoelectronic processing modules and optical interconnection modules makes a pipelined parallel processing system. In the optical interconnection module, a custom designed Fourier Transform lens has been used to reduce the working distance of the lens system. A Computer Generated Hologram (CGH) is written on a liquid crystal display (LCD) that is coupled by a fiber optic plate (FOP) to the optically addressable SLM. The interconnection topology between optoelectronic chips is controlled by changing the CGH patterns, which is calculated in advance. A global interconnectivity among processor arrays is also achievable since the communication channels are constructed via optical path in free-space. The data broadcasting between processors that are located spatially far away can be efficiently implemented by free-space optical links in OCULAR-II's optical interconnection module.

In this paper we present different configurations for a compact free-space optical interconnection (FSOI) module by combining two radial gradient refractive index lenses (GRIN) and/or two arrays of refractive microlenses. Based on our findings with ray-tracing and radiometric analysis we discuss how we have selected the proper optical system configurations and how we have chosen the different design parameters to optimally accommodate different types of opto-electronic emitters such as LEDs, micro-cavity LEDs and VCSELs. We hereby focused on maximizing optical coupling efficiencies and misalignment tolerances while minimizing inter-channel cross-talk Furthermore we discuss the experimental optical characteristics of two such prototype modules that we completed together with the first experimental results of their use in parallel data communication demonstrator systems.

A multi-layered optoelectronic parallel processing system, which is called Optoelectronic Computer Using Laser Arrays with Reconfiguration is shown. This system consists of layers of processing modules, which are composed of electronic programmable processing element array each having parallel optical input/output connected by optical interconnection modules. Every module is designed to be modular and cascadable. The algorithms for this system are also shown which exploit the aggregate bandwidth supplied by optics and the computation versatility given by electronic processors.

In this paper, we investigate the imaging properties of curved large diameter (similar to mm) Gradient Index Polymer Optical Fiber (GIPOF) for massively parallel optical interconnects. We consider that in such large fiber light can propagate following the laws of geometrical optics. A program of ray-tracing through curved GIPOF has been developed based on an algorithm proposed by Sharma et al (1). From simulations we found out that some S-shaped fiber patterns can fulfill all the requirements needed for flexible parallel board-to-board optical interconnects, namely small spot size, low distortion and high transmission efficiency if small divergence angle sources such as VCSELs are used. However the shape and the length of the fiber should be well controlled and the displacement between optoelectronic chips should not exceed a few centimeters.

In the original optical computing paradigm it was generally envisaged that large arrays of simple optoelectronic logic elements would be used to implement single instruction multiple data based algorithms such as data base management and mathematical morphology.

Mathematical morphology and parallel digital logic operations are approaches to early image processing. Usually they are either implemented as software for electronic computers or as optical correlators based on spatial light modulators (SLM).

We present and demonstrate a novel proof-of-principle system with parallel optical input/output to perform mathematical morphological operations on discrete gray level images. Experimental results of erosion and dilation of 8 by 8 images are presented, as well as threshold decomposition of a 6-gray level image into series of binary slices.

In this letter, we present an optoelectronic system for fast gray-level image decomposition into binary slices. To perform thresholding, we are making use of the differential nature of optical thyristors and compare the light level of the image pixels to that of a reference intensity. As input a gray-level image was generated using a nematic liquid crystal spatial light modulator (SLM) and as a reference intensity a VCSEL light source combined with a diffractive fan-out element was used. We also introduced a compact, large field of view telecentric optical system based on gradient refractive index lenses to image between the SLM and the array. A frame rate decomposition of a six gray-level image has been obtained at 1.8 kHz. Future prospects for system improvements are discussed.

The significant progress which has been made irt the development of differential pairs and arrays of differential pairs of light-emitting thyristors has made the construction of optical computing systems,vith high speed interconnections a realistic possibility. In this paper we review our work on the practical implementation of these optoelectronic transceiver devices in systems and demonstrate most of the basic functionalities necessary to build a primitive digital parallel optical processor, We demonstrate the transcription of digital optical data between cascaded single elements and between 8 x 8 arrays of completely-depleted optical thyristor differential pairs. We also show results of digital optical logic NAND, NOR, AND, OR, NOT operations, logic plane to logic plane imaging with a diffractive fan-out and parallel digital data input with a computer controlled liquid crystal micro-display. As an example of a sub-system module which has reasonable complexity we focus on a demonstrator platform which combines optical thyristor logic planes, polarisation-selective diffractive optical elements, liquid crystal variable retarders and large diameter gradient index lenses, and successfully demonstrate dynamically reconfigurable nearest neighbour interconnects. We conclude by discussing the future system performances in the light of system scalability.

The presence of microfilamentous-like structures of tubular appearance (MFS) in cell walls and extracellular sheath material (ES) in a number of isolates of Ophiostoma novo-ulmi Brasier grown on various substrates and following various treatments is reported. Standard fixation or high-pressure freezing methods were used, and cytochemical tests were carried out to detect fungal and host wall components and, in some cases, fungal DNA. In some cases, serial 0.2-μm-thick sections were examined at 120 kV and tilted to obtain stereoscopic images. Whether the fungal cell walls were thick and composed of an outer opaque and inner more electron-lucent layers, or thin and barely perceptible, MFS were observed to extend from the cell cytoplasm as parallel structures across the walls into the surrounding medium, including host cell components in infected elm tissues. MFS were associated (in samples from inoculated trees) with cleavage and desquamation of fungal walls. ES and MFS did not label for cellulose or chitin, but generally labelled slightly for β-(1-3)-glucan and mannose, and strongly for galactose. Only the lucent, inner fungal wall layer labelled for chitin and cellulose. DNA labelling was confined to nuclei and mitochondria in fungal cells from cultures on agar medium; in cells from cultures on millipore membranes, it was pronounced over imprecisely delimited cell regions. The possible ontogeny of MFS components and their importance are discussed. Key words: chitin, Dutch elm disease, fungal fimbriae, fungal walls, gold-complexed probes, microfilamentous structures (MFS).

We show how the polarization properties of VCSELs can be exploited usefully in order to realize reconfigurable optical interconnects. We present three set-ups in which the VCSEL light output falls on a polarization-selective diffractive optical element (PSDOE): polarization switching by current modulation, polarization switching by optical injection, and the use of two independent orthogonally polarized VCSELs. A PS-DOE was designed to generate a different spot array for each of the two orthogonal linear polarization states.

There has recently been significant progress in the development of arrays of fast and sensitive optoelectronic emitters, detectors and transceiver devices. If arrays of these devices are to be successfully incorporated into switching fabrics, data communication or information processing systems, then highly efficient optical systems must be developed to interconnect them. It is indeed important to minimise transmission losses, because the bandwidth of such data channels strongly depend on the amount of optical power impinging on the receivers. The highly divergent nature of some of these sources, such as Lambertian emitters and microcavity LEDs, does not facilitate this task, because of the high insertion losses at the input of the optical system. Moreover we want these systems to be compact, low cost, robust and easily assembled. In this paper we present a novel, hybrid and compact optical system, based on large diameter radial gradient refractive index (GRIN) lenses and microlenses that fulfills these requirements. We also model this system with raytracing software and evaluate its performances experimentally.

We demonstrate reconfigurable, data transparent optical interconnects between planes of optical thyristors using polarization-selective diffractive optical elements in combination with a liquid crystal based polarization controller. A reconfigurable fanout element and a switchable digital optical logical inverter are presented as examples of applications.

A polarization-switching VCSEL is combined with an anisotropic diffractive optical element to demonstrate, for the first time, reconfigurable free-space optical interconnects at a rate of 30 MHz. The same set of components is also used in a proof-of-principle demonstrator for data transparent reconfigurable optical interconnects at a bit rate of 1 MHz and a reconfiguration rate of 40 kHz.

We present a high speed compact optical system with a large field of view, dedicated to optically interconnect planes of microemitters and receivers.