Photorefractive two-wave mixing of rapidly phase modulated signals

We analytically solve the steady-state coupling equations of photorefractive two-wave mixing with a rapidly phase modulated signal for an arbitrary complex coupling constant without the undepleted pump assumption. It shows that the imaginary part of the coupling constant also contributes to the energy transfer in photorefractive two-wave mixing though the time average output intensity is only determined by the real part of the coupling constant. The energy transfer may exist even when the real part of the coupling constant is zero. The photorefractive two-wave-mixing with high-speed sinusoidal phase modulation is discussed in detail.