Application of phase conjugation elements in optical signal processing networks

Summary form only given. Parallel optical information processing systems are well suited for information reduction and preprocessing. Three important specifications for such applications have to be fulfiled: High space-bandwidth-product, amplification for signal restoring, and compensation of aberrations. The introduction of phase-conjugating elements into optical information processing systems will help to realize these specifications. The advantages of phase conjugation in optics, like exact counterpropagation and phase reconstruction, are well known, but the number of experimental realized applications is still small. This report gives a applications of phase conjugation. In a first part we report on setups of phase conjugating mirrors in combination with different types of interferometers (Michelson, Sagnac, and Fabry-Perot). Applications on image subtraction, contrast amplification, phase visualisation, and parallel optical feedback systems will be presented. In all our experiments we used BaTiO ₃ photorefractive crystals and Ar⁺-ion laser for pump/signal waves. In a second part we report on storage of 64 volume holograms in photorefractive BaTiO₃ using a novel orthogonal phase encoding storage technique developed in our group. The new kind of volume memories offers enormous data storage densities, fast access times associated with the parallel readout of large memory portions or pages and a potential associative access and data processing in the optical phase