Interband photorefraction in Sn_2P_2S_6 at visible wavelengths

Abstract

Continuous-wave photorefractive experiments in Sn2P2S6 crystals and interband photorefraction at the visible wavelengths of 514 and 488 nm are presented. Two-wave mixing and Bragg diffraction measurements at 514 nm show grating response times of around 100 μs at moderate light intensities of 0.6 W/cm2, i.e., 2 orders of magnitude faster than measured in the same crystal in the conventional photorefractive regime. A large two-wave mixing gain of up to Γ=60±8 cm−1 is measured, and holes are identified as dominant charge carriers for the interband photorefractive effect.