Abstract

Photorefractive semiconductors have short response times and high sensitivity in the infrared; however, their relatively small electrooptic coefficients are a disadvantage for many devices. One possible solution is to operate at wavelengths closer to the band edge, where the electrooptic coefficient is larger and other nonlinearities may contribute. We have investigated for the first time the photorefractive effect near the band edge of a compound semiconductor. We present measurements of the wavelength dependence of the two-beam coupling gain in semi-insulating GaAs. A large increase in the amount of energy transfer is observed near the band edge, compared to values at longer wavelengths. We discuss possible uses.

© 1989 Optical Society of America