Abstract

Linear photorefractive mixing is limited to constant intensity. However, the operation theory becomes nonlinear when one of the inputs is amplitude modulated. As in electronics, it is often essential to have amplitude modulation. In this paper, we introduce the solution for the nonlinear photo-refractive mixing theory for weakly absorbing materials with constant intensity response-time product in the low coupling limit. The correction terms to the linear solution appear as a low frequency term (possibly including a dc component) and a high frequency multiplicative absorptive ripple that modulates the sum of the linear and low frequency terms. For many photorefractive mixing devices, any amplitude modulations used produce corrections that are extremely small, typically less than 1%, and these vary inversely proportional to the amplitude modulation frequency.

© 1992 Optical Society of America