The effect of bulk light absorption on running photorefractive holograms

The influence of bulk light absorption on running photorefractive holograms is investigated. By solving the coupled wave equations we prove that the b eam intensities, but not the beam phases, can be calculated by averaging th e coupling constant over the crystal thickness. We show the importance of t he effect by calculating the dielectric relaxation time at the crystal fron t, and from that the quantum efficiency from a feedback-controlled experime nt with a 2.05 mm thick BTO crystal. We propose to simulate the effect of bulk light absorption by a rude estima te of the average dielectric relaxation time which is related in a simple w ay to the dielectric relaxation time at the crystal front, in doing so an e rror of less than 10% is introduced.