Abstract

Semiconductors and sillenites represent an important class of photorefractive materials because of their fast response times, ready availability and, in the case of semiconductors, utility in the near infrared. To achieve high two-wave mixing gains in these materials it is necessary to apply external electric fields. The fields may either be dc (in which case resonance must be maintained using techniques such as a moving grating) or alternating. both of these techniques have produced large two-wave mixing gains in semiconductor and sillenite materials; however, the largest gains are produced only for very weak signal beams,^1–3 As the signal beam intensity becomes comparable to the pump beam, a sharp decrease is measured in the effective gain coefficient which cannot be solely explained by pump depletion. This effect is significant for uses such as self-pumped phase conjugation, in which the buildup of the phase conjugate wave will reduce the effective gain and self limit device performance.

© 1992 Optical Society of America