Secondary Grating Formation by Readout at Bragg-null Incidence

We show that when a dynamic hologram is read out by illumination at the Bragg nulls of a previously recorded grating the diffracted beam inside the medium can result in the recording of two secondary gratings that alter the final selectivity curve. This is confirmed experimentally. This effect can cause cross talk in hologram multiplexing that is stronger than interpage cross talk when a small number of holograms with high diffraction efficiencies are multiplexed

Optical memory for computing and information processing

The high data transfer rate achievable in page-oriented optical memories demands for parallel interfaces to logic circuits able to process efficiently the data. The Optically Programmable Gate Array, an enhanced version of a conventional FPGA, utilizes a holographic memory accessed by an array of VCSELs to program its logic. Combining spatial and shift multiplexing to store the configuration pages in the memory, the OPGA module is very compact and has extremely short configuration time allowing for dynamic reconfiguration. The reconfiguration capability of the OPGA can be applied to solve more efficiently problems in pattern recognition and digit classification

Optically programmable gate array

The Optically Programmable Gate Array (OPGA), an optical version of a conventional FPGA, benefits from a direct parallel interface between an optical memory and a logic circuit. The OPGA utilizes a holographic memory accessed by an array of VCSELs to program its logic. An active pixel sensor array incorporated into the OPGA chip makes it possible to optically address the logic in a very short time allowing for rapid dynamic reconfiguration. Combining spatial and shift multiplexing to store the configuration pages in the memory, the OPGA module can be made compact. The reconfiguration capability of the OPGA can be applied to solve more efficiently problems in pattern recognition and database search

Optically programmable gate array

The Optically Programmable Gate Array (OPGA), an optical version of a conventional FPGA, benefits from a direct parallel interface between an optical memory and a logic circuit. The OPGA utilizes a holographic memory accessed by an array of VCSELs to program its logic. An active pixel sensor array incorporated into the OPGA chip makes it possible to optically address the logic in a very short time allowing for rapid dynamic reconfiguration. Combining spatial and shift multiplexing to store the configuration pages in the memory, the OPGA module can be made compact. The reconfiguration capability of the OPGA can be applied to solve more efficiently problems in pattern recognition and database search