Enhanced near-infrared photorefractive properties of Te-doped Sn2P2S6

We investigate different types of ferroelectric photorefractive Sn2P2S6 at different wavelengths in the red and infrared. We show that modifying the growth conditions and doping with Te can efficiently improve the photorefractive properties of Sn2P2S6. Photorefractive two-beam coupling gain increases for Te-doped Sn2P2S6, up to 17 cm-1 at a wavelength of 633 nm and up to 7 cm-1 at 860 nm, compared to conventional "yellow" Sn2P2S6 which has a gain of 4-7 cm-1 at 633 nm and 2 cm-1 at 860 nm. We demonstrate self-pumped phase conjugation in ring cavity scheme at 780 nm for Te-doped Sn2P2S6 with a reflectivity of up to 30% in a relatively short rise time of less than 50 ms for 2 W/cm2 pump intensity.