Photorefractive properties of near-stoichiometric LiNbO3 grown from congruent melts containing K2O

The photorefractive properties of nominally pure near-stoichiometric LiNbO3 crystals grown from congruent melts containing 11 mol % K2O are studied, a nd some photorefractive properties which are very different from those in c ongruent LiNbO3 crystals are observed. Large stationary energy transfer (Ga mma (max)=25 cm(-1)) exists in near-stoichiometric crystals though the phot ovoltaic field is dominant. The light-induced scattering fanning is markedl y asymmetric in the crystals, which is very different from the symmetric fa nning observed in congruent ones. Our analysis shows that these differences are caused by the large photovoltaic field and the relatively small densit y of filled traps in as-grown near-stoichiometric LiNbO3. (C) 2001 American Institute of Physics.