IR recording in photorefractive crystals via two-step processes

Summary form only given. At high light intensities shallow levels are always involved in the holographic recording process in photorefractive crystals. Two level models - the two-center and the three-valence model - were developed and successfully applied for the description of the light-induced charge transport in many crystals. The shallow levels can be populated by illumination with visible or UV light forming states with relatively long life times, thus sensitizing the crystals for holographic recording with IR light.