Application of Raman spectroscopy for measurement of photorefractive damage profile in LiNbO₃ crystals

We demonstrate that the Raman spectroscopy method may be effectively used for accurate determination of optical damage profiles in LiNbO₃-based elements used in the various devices utilizing high-power laser beams. It has been established, that there is an irreversible fraction of the optical damage induced only by the high-intensity (≥ 25 kW/cm²) illumination for a long time, and it has accumulative character with exposure time in nominally pure crystals. This irreversible effect was related to the optical fatigue of a material.