Growth of KTP crystals with large {0 0 1} facets

Potassium titanyl phosphate (KTP) single crystals have been grown by the top-seeded pulling (in Z-direction) from modified fluxes. The fluxes contained a mixture of two solvents, the conventional K₆P₄O₁₃ phosphate and excessive amounts of PbO, 70-80 wt% relatively to the phosphate. Crystals with a single domain (0 0 1) growth sector core have been obtained within a unique formation of the (0 0 1) facet at the growth interface entrapping most of its area. Room temperature electrical resistivity (dc) measurements have been carried out across the facet area, and the transverse compositional homogeneity has been confirmed. The high resitivity values, 4×10⁷ Ω cm on the average, are indicative of the improved crystal stoichiometry. The longitudinal stoichiometry gradient has been also examined by measuring the Curie temperatures at the crystal top and bottom and found to be small. The suitability of such crystals for selective applications, such as fabricating Z-cut plates for processing periodically poled domain structures needed in quasi-phase-matched frequency doubling of laser radiation, is demonstrated.