Optoelectronic integrated systems based on free-space interconnects with an arbitrary degree of space variance

It is appealing to contemplate how VLSI or wafer-scale integrated systems incorporating free-space optical interconnection might outperform purely electrically interconnected systems. This paper first provides a uniform treatment of a general class of optical interconnects based on a Fourier-plane imaging system with an array of sources in the object plane and an array of receptors in the image plane. Sources correspond to data outputs of processing “cells,” and receptors to their data inputs. A general abstract optical imaging model, capable of representing a large class of real systems, is analyzed to yield constructive upper bounds on system volume that are comparable to those arising from “3-D VLSI” computational models. These bounds, coupled with technologically derived constraints, form the heart of a design methodology for optoelectronic systems that uses electronic and optical elements each to their greatest advantage, and exploits the available spatial volume and power in the most efficient way. Many of these concepts are embodied in a demonstration project that seeks to implement a bit-serial, multiprocessing system with a radix-2 butterfly topology, and incorporates various new technology developments