Nonresonant enhancement of the nonsteady-state holographic currents in photoconductive crystals

In this paper, we report on nonresonant excitation holographic currents in an external sinusoidal electric field with frequency Ω. We have obtained general expression for the nonsteady-state photocurrent amplitude excited in an AC electric field. Dependence of the nonsteady-state photocurrent amplitude versus the frequency of phase modulation ω was measured in n-type photorefractive Bi₁₂SiO₂₀ crystal. We observed linear growth of the signal for low modulation frequencies up to a certain characteristic cut-off frequency and frequency-independent region for high modulation frequencies.