Abstract

The presence of natural optical activity in Bi₁₂SiO₂₀, renders the two-beam coupling effects in this crystal highly sensitive to the polarization direction of the interacting beams. We derive analytic expressions for the steady state signal amplification when a strong pump beam and a weak signal beam write a grating G through the diffusion of photo-electrons. Two commonly used transverse configurations, G// <001>and G//<110>, are studied. We prove the experimentally found fact that only the <001> orientation is suitable for signal amplification. The results obtained for the diffusion regime can be applied, without significant error, to the more common and more intricate drift regime in which a bias electric field is applied to the crystal to enhance the coupling effect.

© 1987 Optical Society of America