Abstract

The intensity dependence of wavefront reflectivity in four-wave mixing in photorefractive materials is highly nonlinear. Use of this nonlinearity can produce interesting image modifications such as image intensity inversion. Intensity inversion, i.e., l_out ∝ 1/l_in, is obtained when the intensity of the signal beam, l_in, is very much greater than the total intensity of the reference and readout (pump) beams.^1,2 We have observed inversion for a dynamic range of the signal beams between 10:1 and 100:1 using bismuth silicon oxide as the nonlinear medium. Experimental results showing the extent of inversion as a function of the beam intensities, interaction angle, and applied voltages are presented.

© 1986 Optical Society of America