Time-space dynamics of holographic recording and fixing in LiNbO_3:Fe:Mn crystals

摘要

The time-space dynamics of the recording and fixing of photorefractive holograms in doubly-doped LiNbO_3:Fe:Mn crystals are analyzed by jointly and numerically solving the set of time-differential two-center material equations and the set of space-differential coupled-wave equations. In the formulation, the absorption of both the recording light and the sensitizing light is included. The results for optimizing the holographic recording are similar to those obtained by the previous steady-state solving. In this paper, therefore, a special attention is paid on the time-space evolution of the intensity and phase distributions of the induced space-charge fields and the exciting interference pattern of the two beams for recording or the readout and diffracted beams for coherent erasing. It is interesting to find that during the time development of hologram there is a spatially changed direction of energy transferring between the two-coupled beams, which depends spatially on the relative phase difference between the induced space-charge field and the exciting interference pattern. The energy transferring direction will be reversed as the relative phase difference becomes opposite in the sign. As a result, the spatial figures of the isophase and the recording or recorded holographic fringes are depicted, which gives a full understanding for the formation of photorefractive hologram in LiNbO_3:Fe:Mn.