Theory of photorefractive dynamic grating formulation

The photorefractive holographic recording and two-beam coupling are both dy namic grating formulation process. The interference light intensity of the two coherent beams induces a phase grating though photo-induced refractive index variation and the phase grating changing the intensities of the two b eams through beam-coupling take place at the same time. By solving simultan eously the band transport equations and wave-coupled equations, and using t he light intensity modulation as the main variable, the analytic solution i s obtained, which is valid for any light intensity modulation and constant light excitation efficiency. Here all the mechanics of drift, diffusion and photovoltaic effect are considered. The result shows that the modulation o f the dynamic grating varies more slowly compared with that of the linear m odulation approximation.