Developing light intensity dependence of the diffraction efficiency of thermal fixed holograms in LiNbO3:Fe

Abstract We observed developing light intensity dependence of the diffraction efficiency of thermally fixed holograms in LiNbO3:Fe. The diffraction efficiency decreases for low illumination. At high intensity there was obtained a saturation effect. This dependence was weaker for highly oxidized crystals. The proper description of the results seems to require a two-photorefractive-center model. This effect is important from the practical point of view. It has to be considered that one has to provide the adequate illumination conditions in applications of these fixed holograms.