Abstract

Gain is one of the most attractive aspects of the photorefractive effect. Phase conjugators and other applications become possible when photorefractive gain exceeds absorption losses. Semiconductors, such as InP and GaAs, have small electro-optic coefficients, so it has been necessary to apply electric fields of several kV/cm to realize large gains. In InP:Fe, a gain of 3 cm^-1 first was reported with a 10 kV/cm AC applied field¹ and later a gain of 4 cm^-1 was obtained with an 8 kV/cm DC field.² Recently gains as large as 6 cm^-1 have been reported for an 8 kV/cm DC field.³ While it is not possible to have such large gains in InP:Fe without an applied field, the high voltages required are not practical for device applications.

© 1990 Optical Society of America