Two-wave mixing and energy transfer in Bi(12) SiO(20) crystals: application to image amplification and vibration analysis.

The energy transfer between two beams (signal and reference, respectively) writing a dynamic-volume hologram in photorefractive BSO crystals is applied to the image amplification of a diffuse object. The image intensity transmitted by the crystal is amplified 10x in the presence of the pump reference beam. The crystal is used in the drift recording mode (applied electric field, E(0) = 10 kV cm(-1); fringe spacing, Lambda = 3 microm), and beam coupling is induced by the nonlocal response of the crystal that is due to the fringe displacement at a constant speed. We have applied this two-wave mixing configuration to a real-time optical-processing operation; the related energy transfer and stationary image amplification permit the mode pattern visualization of a vibrating structure.