Photorefractive properties of potassium lithium niobate crystals

We report the photorefractive properties of K3Li2-xNb5+xO15+2x crystals gro wn by the edge-defined, film-fed technique. The crystals with lithium/nioba te ratio from 18.5/51.5 to 26/44 are grown and investigated by two-beam cou pling technique. The crystal of composition K3Li1.783Nb5.687O16.61 exhibits an intensity coupling constant of 8 cm(-1) and an effective trap density o f 1.8 x 10(22) m(-3). The photorefractive majority carriers are electrons i n as-grown crystals. The grating recording time and erasure time are 530 an d 260 ms, respectively, at an intensity of 2 W/cm(2). (C) 1999 American Ins titute of Physics. [S0003-6951(99)03610-4].