The analytic expressions for the first three higher order harmonics of the space charge field versus time and the applied field are 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. We aslo study the effect of the applied field on recording of the first three higher order harmonics of the space charge field. 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. With an applied field, higher-order harmonics of the space-charge field show oscillating attenuation versus time until to reach saturation state. The oscillating is strong as the applied field increases with shorter oscillating period. The oscillating amplitude of the space-charge field increases while the contribution of the higher-order harmonics are considered.