Submillisecond photorefractive response time of KNbO(3):Rb(+)

We investigate the photorefractive response time of diffraction gratings in Rb(+)-doped KNbO(3) crystals. Two components of charge carriers, with different response times, are found to contribute to the photoinduced index gratings. One component, which contributes to approximately 70% of the index grating, shows a submillisecond rise time when the total intensity of the writing beams is larger than 5 W/cm(2). The dependence of the response time on the light intensity and the grating wave vector is also investigated.