Dynamic Photorefractive Interconnects With Analog Weights

Abstract

Multiplexing of holographic gratings has potential application in the implementation of optical interconnects betweeen individual processing elements (or neurons) of two distinct planes in a neural network. Therefore, the capability of continuously modifying a given strength (or weight) without affecting the others is a critical issue. In this paper, we analyze grating erasure in photorefractive materials for the realization of interconnects with analog weights. The effects of both intensity and phase modulation of the writing beams on the diffraction efficiency and on the response time are considered. The phase modulation analysis includes the double-exposure and time-average techniques. Some insight on the limiting factors to the storage capacity which ultimately determines the number of possible interconnections are also given. Finally, preliminary results of an interconnect system that utilizes fast liquid crystal modulators are described.