Investigation of the dielectric, optical and photorefractive properties of Sb-doped Sn_2P_2S_6 crystals

摘要

In this work we report results on electro-physical, optical and photorefractive investigations for Sb-doped Sn_2P_2S_6 crystals. The crystals are obtained by two methods: the vapour-transport technique and the Bridgman technique using stoichiometric Sn_2P_2S_6 composition with different amounts of antimony in the initial compound. The good optical quality of the crystals obtained with the Bridgman technique is underlined. The dependences of the photorefractive two-beam coupling coefficient and the grating build-up time are investigated at the wavelength of 633 nm. It is found that the sample doped with 1.5% of Sb is characterized by an optimal combination of the main photorefractive parameters exhibiting a fairly high two-beam coupling coefficient (up to 20 cm~(-1)) and a short response time (1.3 ms) that is the shortest among all the previously studied Sn_2P_2S_6 crystals in the red spectral region.