High-Speed Parallel Optical Processors of Photorefractive GaAs

It is known that a photorefractive crystal can act as a phase conjugate mirror via four-wave mixing or self-pumped phase conjugation. The use of a phase conjugate mirror in the interferometric system for parallel mathematic operations has been reported[1-6]. The photorefractive materials used are BaTiO3[l-5] and Bi12SiO20[6]. The phase conjugation process can improve dynamic stability by reducing the sensitivity to beam path fluctuations and alignment. However, the slow responses of these materials make operations not only slow, but also sensitive to environmental fluctuations, such as air turbulence and vibrations of time constants shorter than those of the material response time.