Near-infrared-sensitive photorefractive Sn2P2S6 crystals grown by the Bridgman method

Ferroelectric tin hypothiodiphosphate (Sn${}_2$ P${}_2$ S${}_6$ ) crystals are well-known for their significant piezoelectric, electro-optic, and nonlinear optical properties. These crystals have usually been grown by a vapor transport technique. We report in this paper on the first study of photorefractive nonlinearity in Sn${}_2$ P${}_2$ S${}_6$ crystals grown by the Bridgman method. Pronounced photorefraction is observed in the near-infrared region of the spectrum even with no preliminary optical sensitizing.