Abstract

We present data on the enhanced photorefractive properties of Sn₂P₂S₆ as a result of doping by Te. These new crystals were obtained by vapor-transport technique using stoichiometric Sn₂P₂S₆ composition with an additional amount of Te up to 3 mol. % in the initial compound. The optical absorption spectra of the grown crystals contain an additional band located near the fundamental absorption edge, which increases with the Te concentration. Sn₂P₂S₆:Te crystals are found to exhibit larger two-beam coupling gain coefficients G (up to 12 cm⁻¹ at a wavelength of 633 nm and up to 7 cm⁻¹ at 780 nm) as compared to pure Sn P₂S₆ (4-7 cm at 633 nm and 2.5 cm⁻¹ at 780 nm). Additionally, the grating build-up becomes faster in comparison with both, nominally pure yellow and brown Sn₂P₂S₆ modified by the growth conditions. The typical time response is 2-5 msec for He-Ne laser irradiation with an average intensity I = 0.3 W cm⁻². The results on a self-pumped ring-loop beam oscillator based on such Te-doped Sn₂P₂S₆ crystals studied at 633 and 780 nm show the reflectivity close to its theoretical limit and fast rise time of the conjugated beams.

© 2003 Optical Society of America