Photorefractive Material KNSBN:Cu

This paper reports systematically the crystal growth and photorefractive properties of Cu-doped KNSBN, and the mechanism of the Cu ions' effects on the photorefractive properties of KNSBN. The Cu ions doped in KNSBN can form two energy levels in the band gap, thus play important roles in the photorefractive process. They increase the effective electron combination center concentration, which results in the modification of the photorefractive properties of KNSBN. The two-wave coupling gain coefficient of KNSBN: Cu is two times greater than that of KNSBN. The photorefractive sensitivity of Cudoped KNSBN is estimated to be in the order of 10 -3 cm 2 /J. Its cat-SPPC reflectivity can reach 65％ corresponding to an response time less than 8 s.