Growth of BPO4 single crystals from Li2O–MoO3 flux

A new flux system, Li2O–MoO3, has been applied to growing BPO4 single crystals. Transparent BPO4 single crystals with sizes up to 31×18×16 mm3 have been successfully grown from the new flux by the top-seeded solution growth method. The viscosity of solution using this new flux decreased significantly compared with that of previously utilized Li4P2O7–Li2O flux. The solubility was measured and favorable concentration for BPO4 crystal growth was in the range of 55–64%. The powder SHG effect of as-grown BPO4 crystal was observed and its intensity was about twice as large as that of KDP. The laser damage threshold of BPO4 crystal at λ=1.064 nm and τ=8.0 ns is about 10.3 GW/cm2.