Defect tolerance of holographic configurations in ORGAs

Abstract

Optically reconfigurable gate arrays (ORGAs) have been developed as a type of multi-context field programmable gate array to realize fast reconfiguration and numerous reconfiguration contexts. Along with such advantages, ORGAs have high defect tolerance. They consist simply of a holographic memory, a laser diode array, and a gate array VLSI. Even if a gate array VLSI includes defective areas, the perfectly parallel programmable capability of ORGAs enables perfect avoidance of those defective areas through alternative use of other non-defective areas. Moreover, holographic memories to store contexts are known to have high defect tolerance because each bit of a reconfiguration context can be generated from the entire holographic memory. Moreover, the damage of some fraction rarely affects its diffraction pattern or a reconfiguration context. Therefore, ORGAs are very robust against component defects in devices such as laser arrays, gate arrays, and holographic memory, and are particularly useful for space applications, which require high reliability. However, to date, the degree to which defects in a holographic memory affects holographic configurations has never been analyzed. Therefore, this paper describes analysis results of defect limitations of holographic configurations.