Photorefraction in tin hypothiodiphosphate in the near infrared

Ferroelectric photorefractive Sn2P2S6 crystals become more sensitive to cw radiation of a Nd3+: YAG laser (λ = 1.06 µm) by preexposure with incoherent white light. Space-charge formation and hologram recording are dominated by a diffusionlike charge transport, leading to an ultimate gain factor for transmission gratings that exceeds 6 cm−1 at a laser intensity of approximately 50 W/cm2.