Abstract

In 1984 Ducharme and Feinberg¹ showed that the speed of the photorefractive effect in barium titanate was not a linear function of the light intensity I but varied instead as I^x with x < 1. This sublinear dependence prevailed over 4 orders of the light intensity (0.01 W/cm² < I < 100 W/cm²). They also showed that the exponent x increased with increasing temperature. In 1988, Mahgerefteh and Feinberg² showed that the speed of the photorefractive effect in barium titanate obeyed the same I^x power law for pulsed illumination as well as for cw illumination, even though the peak intensities used in the pulsed case were 10⁴ times that of the cw experiments. This result suggested that the I^x power law was valid for a range spanning 8 orders of magnitude in the light intensity.

© 1990 Optical Society of America