Threshold effect of incident light intensity on the photorefractive light-induced scattering in double-doped lithium niobate crystals and its application

The formation mechanism of fanning noise in lithium niobate crystal is theo retically studied using the multi-wave mixing model. The threshold effect o f incident light intensity for the photorefractive light-induced scattering in double doped lithium niobate crystal is explained by combining the mult i-wave mixing model with the two-photorefractive-sensitive-center model for single charge-carrier. Light amplification competition between the fanning noise and the signal beam in doped lithium niobate crystals is also studie d. The existence of optimum photovoltaic field and optimum pump intensity i s predicted theoretically.