Abstract

We propose an optical circuit unit consisting of two beam splitters and two Ba- TiO₃ phase conjugate mirrors (PCMs). The reflective gain of a PCM is up to 260% using r42 electrooptic coefficient. Circuits of this type can be connected in cascade because of the high gain. An input beam goes to the first PCM (PCM₁) through the beam splitter, and its amplified reflected beam is led to the second PCM (PCM₂). As the two PCMs are connected by the two beam splitters, a feedback loop is constructed between them. PCM₁ forms a phase conjugate (PC) image of the input in the mask plane, and PCM₂ forms a PC image of this PC image, that is, it reconstructs the original in the output plane. Because of the beam splitters a beam passes back and forth between the two PCMs. In the mask plane, the PC image by PCM₁ and the original image by PCM₂ coincide although they propagate in opposite directions. Controlling transmittance of the mask, we can perform a nonlinear operation to the input image with this feedback system.

© 1989 Optical Society of America