Optical associative memory using photorefractive LiNbO/sub 3/:Fe hologram, and LiNbO/sub 3/:Fe and BaTiO/sub 3/ phase conjugate mirror

Experimental results are presented for phase conjugate (PC) wave generation, and the possibility of an application to an optical associative memory is discussed. Using an iron-doped lithium niobate single crystal, greater than 300% reflection efficiency was achieved by the degenerate four-wave mixing method, which was almost independent of the total incident optical intensity. The generator was then applied as a PC mirror to an all-optical associative holographic memory to reflect and amplify the diffracted beams. The retrieved output image was formed by using partial input illumination. Using a barium titanate single crystal, a PC reflection efficiency of about 70% was obtained by the self-pumping method. In order to accelerate the speed of the generation, a novel method called accelerated self-pumped phase conjugation (SPPC) was used. It was demonstrated that the accelerated SPPC could be directly applied to an optical associative memory to reflect the diffracted beams if a readout beam with a power of 40 mu W was used.<
>