A multi-context holographic memory recording system for Optically Reconfigurable Gate Arrays

Optically reconfigurable gate arrays (ORGAs) offer the possibility of providing a virtual gate count that is much larger than those of currently available VLSIs by exploiting the large storage capacity of a holographic memory. The first ORGA was developed to achieve rapid reconfiguration and a number of reconfiguration contexts; it consisted of a gate array VLSI, a holographic memory, and a laser diode array. The ORGA achieved a 16 mus to 20 mus reconfiguration period that was faster than that of FPGAs, with 100 reconfiguration contexts. However, the ORGA requires the gate array to halt during reconfiguration. Therefore, the ORGA cannot be reconfigured frequently because of the associated reconfiguration overhead. On the other hand, new ORGA-VLSIs that have less than 10 ns reconfiguration capability without any related overhead have already been fabricated. However, to date, a multi-holographic reconfiguration system that is suitable for such rapidly reconfigurable ORGA-VLSIs without any overhead has never been developed. For such realization, this paper proposes a four-context ORGA architecture and a multi-context holographic memory recording system used for it. In addition, experimentally demonstrated results of recording a holographic memory and reconfiguring an ORGA-VLSI are described.