PHOTOREFRACTIVE PROPERTIES OF POTASSIUM LITHIUM NIOBATE CRYSTALS

We report the photorefractive properties of K3Li2−xNb5+xO15+2x crystals grown by the edge-defined, film-fed technique. The crystals with lithium/niobate ratio from 18.5/51.5 to 26/44 are grown and investigated by two-beam coupling technique. The crystal of composition K3Li1.783Nb5.687O16.61 exhibits an intensity coupling constant of 8 cm−1 and an effective trap density of 1.8×1022 m−3. The photorefractive majority carriers are electrons in as-grown crystals. The grating recording time and erasure time are 530 and 260 ms, respectively, at an intensity of 2 W/cm2.