Manifestation of long-lived photosensitivity gratings in two-wave mixing experiments with sillenite crystals

摘要

Transient recording dynamics and hologram fixing and retrieval were observed in photo refractive Bi12SiO20 crystal in two-wave mixing experiments under an ac electric field. These effects were explained by the light- and space-charge-induced spatial modulation of sample photoconductivity originating from the nonequilibrium initial population of relevant photoactive levels. Such a photosensitivity grating exhibits a relaxation time of several hours even when the crystal is illuminated by a spatially uniform light beam. Thus we have shown for what is the first time to our knowledge that optical information can be stored in a photoconductive crystal as a spatially modulated photosensitivity rather than in the form of a space charge. (C) 2002 Optical Society of America. [References: 12]