OBSERVATION OF PHOTOREFRACTIVE EFFECT OF KNbO₃ CRYSTAL AT μW ILLUMINATION

The photorefractive effects of the as-grown and proton-implanted KNbO₃ crystals were studied by two-wave mixing at 62.2μW/cm² illumination. At this pump power level, the as-grown crystal showed little photorefractive effect, while the proton-implanted crystal showed an obvious effect. Furthermore, there seemed to exist two photorefractive gratings with response times of 22.54 and 1596.30s, at 62.2μW/cm² pump power level, in the proton-implanted sample. This phenomenon has been attributed to the influence of proton-implantation.