Demonstration and architectural analysis of complementary metal-oxide semiconductor /multiple-quantum-well smart-pixel array cellular logic processors for single-instruction multiple-data parallel-pipeline processing.

We present an optoelectronic-VLSI system that integrates complementary metal-oxide semiconductor/multiple-quantum-well smart pixels for high-throughput computation and signal processing. The system uses 5 x 10 cellular smart-pixel arrays with intrachip electrical mesh interconnections and interchip optical point-to-point interconnections. Each smart pixel is a fine grain microprocessor that executes binary image algebra instructions. There is one dual-rail optical modulator output and one dual-rail optical detector input in each pixel. These optical input-output arrays provide chip-to-chip optical interconnects. Cascading these smart-pixel array chips permits direct transfer of two-dimensional data or images in parallel. We present laboratory demonstrations of the system for digital image edge detection and digital video motion estimation. We also analyze the performance of the system compared with that of conventional single-instruction-multiple-data processors.

Space-variant interconnections based on diffractive optical elements for neural networks: architectures and cross-talk reduction.

Optical architectures for fully connected and limited-fan-out space-variant weighted interconnections based on diffractive optical elements for fixed-connection multilayer neural networks are investigated and compared in terms of propagation lengths, system volumes, connection densities, and interconnection cross talk. For a small overall system volume the limited-fan-out architecture can accommodate a much larger number of input and output nodes. However, the interconnection cross talk of the limited-fan-out space-variant architecture is relatively high owing to noise from the diffractive-optical-element reconstructions. Therefore a cross-talk reduction technique based on a modified design procedure for diffractive optical elements is proposed. It rearranges the reconstruction pattern of the diffractive optical elements such that less noise lands on each detector region. This technique is verified by the simulation of one layer of an interconnection system with 128 x 128 input nodes, 128 x 128 output nodes, and weighted connections that fan out from each input node to the nearest 5 x 5 array of output nodes. In addition to a significant cross-talk reduction, this technique can reduce the propagation length and system volume.

Time multiplexing and control for optical cellular-hypercube arrays.

We discuss the cellular-hypercube optical free-space interconnection architecture and its implementation by two-dimensional smart-pixel optoelectronic cellular arrays. We emphasize the behavior of the cellular hypercube in performing shift-invariant parallel shifts of data, a basic requirement of most single-instruction multiple-data algorithms. We present a time-multiplexing scheme for realizing the cellular hypercube, showing that the communication time is inversely proportional to the number of optical detectors per cell. We also present an improved hybrid interconnection network with improved performance that combines the cellular hypercube and mesh, using optics for the longer-distance connections and electronics for nearest-neighbor connections.