Observation of optical inhomogeneities in flux grown KTP crystals

Optical inhomogeneities in potassium titanyl phosphate crystals grown from different fluxes have been investigated. In the crystals grown from a flux which contains tungsten, striations parallel to the {011} faces were observed. The main reason for forming striations is the change in tungsten concentration with change in growth rate. In the case of a potassium phosphate flux, no striations were observed in the crystal which was grown at almost the same temperature and stirring conditions as for the tungstate flux. We can conclude that the phosphate flux is more suitable for the growth of optically good crystals for KTP as laser harmonic converters.