Temperature dependence of photorefractive properties of a Cu-doped barium strontium potassium sodium niobate crystal

The gain of forward two-wave mixing (FTWM) and time response of a Cu-doped barium strontium potassium sodium niobate (KNSBN) crystal are investigated at 514.5 nm in the temperature range 20–120°C. It is found that the gain reaches its maximum value at about 90°C. The effective photorefractive charge density decreases with temperature. The response and erasure rates increase with increasing temperature. Moreover, the erasure process can be described by a diexponential function. A band diagram of the two-center charge transport model is presented. The phenomena are explained qualitatively.