PULSED-PHOTOEXCITATION STUDIES IN PHOTOREFRACTIVE KNBO3

Measurements of the space-charge grating buildup in the dark are performed in potassium niobate using short pulse excitation at a wavelength of 532 nm. The experiments allow the separate determination of the lifetime of the photoexcited electrons and of their mobility in a number of KNbO3 crystals. The lifetime of (3.9+/-0.2) ns is shown to be an intrinsic property of KNbO3. Estimates of the electron mobility are refined to (0.5+/-0.1) cm2 V-1 s-1 in reduced KNbO3. From saturation effects we derive an electron donor photoexcitation cross section of (2.6+/-1.0)X 10(-17) CM2.