Photorefractive Gain Dependence on Diffraction Efficiency in Bi12SiO20 Crystal

Photorefractive gain in Bi12SiO20 (BSO) crystal was studied using a two-wave mixing configuration. It was clear that the gain was strongly dependent on the incident plane in the BSO crystal rotated clockwise around the direction where the rotation angle of zero coincided with the direction. There were two regions in the gain, i.e., the gain was negative in the range of 10°~170° and positive in the range of 190°~350°. The energy exchange between two coherent beams could be explained by the diffraction efficiency of the diffracted beam being a function of the rotation angle of the crystal. The experimental results agreed well with the theoretical results.