Photorefractive and photochromic effects in Sn2P2S6 at various temperatures

Photochromic effect in nominally pure and doped Sn2P2S6 photorefractive crystals is investigated in the temperature range 120–310 K. This effect determines a mechanism of the amplitude hologram formation at low temperatures, and we show that a competition between the photorefractive (phase) and the amplitude gratings occurs at increasing temperature.