Perturbative analysis of effect of applied electric field on high order response of photorefractive effects

The analytic expressions for the first three higher-order harmonics of the space-charge field versus time and the applied field were presented by using perturbative expanding to the hopping model of Feinberg. The results are valid for arbitrary strengths of characteristics' fields in the photorefractive materials with arbitrary values of the modulation depths. The effect of the applied field on recording of the first three higher-order harmonics of the space charge field was also studied. It shows that the effect on the space charge field is very small at case of large diffusion field. The applied field for the maximum saturation values becomes small with the order increasing.