Abstract

Sn<sub>2</sub>P<sub>2</sub>S<sub>6</sub> is a fast responding photorefractive ferroelectric material with very attractive properties for applications in the near infrared. It exhibits high electro-optic coefficients up to <i>r</i> <sup>T</sup> <sub>111</sub> = 174pm/V at 633nm and room temperature, large transparency range in the infrared (530–8000 nm), and a high photorefractive sensitivity. We show that modifying the growth conditions and doping with Te can efficiently improve the photorefractive properties of Sn<sub>2</sub>P<sub>2</sub>S<sub>6</sub>. Photorefractive two-beam coupling gain at 860 nm increases from about 2 cm<sup>-1</sup> in conventional " yellow" Sn<sub>2</sub>P<sub>2</sub>S<sub>6</sub> to about 7 cm<sup>-1</sup> in Te-doped samples and 14 cm<sup>-1</sup> in modified " brown" samples. We demonstrate self-pumped phase conjugating reflectivities above 50 % and rise time of about 50 ms for 2.5 W/cm<sup>2</sup> pump intensity at 860 nm.

© 2005 Optical Society of America

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