Spatial distribution of power coupling in self-pumped photorefractive reflection gratings

The spatial distribution of the power transfer achieved by contradirectional two-beam coupling using self-pumped photorefractive reflection gratings is investigated in two materials with different photorefractive gain coefficients, LiNbO3:Fe and KNbO3:Fe. Incremental portions of the volume grating are erased optically by inducing thin optical damage planes, reducing the overall two-beam coupling efficiency. By monitoring the effect of local grating disruption, the distribution of power transfer is spatially resolved throughout the crystal, and the results are found to be in agreement with our theoretical predictions.