Growth of large single crystals of KTiOPO 4 (KTP) from high-temperature solution using heat pipe based furnace system

Abstract

A process is reported for crystal growth of KTiOPO 4 from its solution in K 6P 4O 13 using a seeded, slow cooling technique. A new furnace system is reported for use in the process, its key feature being a heat pipe providing for a high degree of spatial temperature uniformity throughout the growth solution. Initial surface dissolution appears necessary to achieve flaw-free growth immediately off a seed. Avoidance of solution inclusion flawing in advanced stages of growth requires a crystal orientation configuration and rotation pattern that does not give rise to stable regions of uncirculating growth solution. Through the process, 10-day growth runs routinely produce flaw-free crystals large enough to yield plates 10 × 10 × 7 mm 3 oriented in the optimal direction for second harmonic generation having properties measured to be at least as good as KTiOPO 4 grown by other methods.