Abstract

An information-bearing laser beam propagating in a photorefractive material, such as barium titanate, can generate its own phase-conjugated replica with high fidelity, as a result of beam fanning. We have studied the temporal stability in this self-pumped phase conjugation (SPPC) and its accompanying total-internal-reflection (TIR) ring, as a function of the laser intensity, the orientation between the c-axis of the crystal and the beam, as well as the spatial-frequency content of the beam. This is important in applications such as dynamic associative memory storage and real-time optical signal processing. The degree of stability varies with the spatial-frequency content of the incident beam. There are regimes of unstable (chaotic) behavior and regimes with relatively stable output. We have considered the use of an incoherent second beam to stabilize the SPPC and to improve the diffraction efficiency of readout from the crystal. We have also studied the trade off between the storage and recall of information in the crystal by exploiting SPPC and TIR ring patterns.

© 1990 Optical Society of America