Abstract

Although the photorefractive sensitivity of the semiconductors is many orders of magnitude larger than the oxides, their small Pockels electro-optic coefficient has been a serious drawback. By taking advantage of the quadratic effects near the band-edge, nonlinearity and sensitivity of semiconductor photorefractivcs can be dramatically improved. Recently, two-beam-coupling gain coefficients of 16.3 cm⁻¹ in GaAs [1] and 26.0 cm⁻¹ in InP [2] have been reported near the band-edge. Quantum confinement of excitons in multiple quantum wells (MQWs) provides an additional enhancement of the resonant electro-optic nonlinearities. We have recently demonstrated how enhanced photorefractive sensitivity can be obtained in semi-insulting MQW devices [3]. These devices were made semi-insulting through ion-implantation to provide sufficient density of traps for the photorefractive process as well as relieving the need for any pixelation.

© 1991 Optical Society of America