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Reduced-Pressure Melts Growth of the Vacuum Ultraviolet Double Frequency Crystal KBe2BO3F2 (KBBF)

A reduced-pressure melts growth method was first presented to grow the vacuum ultraviolet double frequency crystal KBe2BO3F2 (KBBF). The bulk KBBF crystal, with a dimension of about 11mm×10mm×5mm, has been grown successfully, and the grown crystal exhibits a high optical homogeneity except for the seed zone. The optical transmittance spectrum of the grown KBBF crystal was measured and it indicated that the high-frequency absorption edge is observed at 160nm, the transmittance is up to about 70% between 250nm and 400nm. The results show that the reduced-pressure melts growth is a promising growth method for bulk KBBF crystal and the grown KBBF crystal is possible for applying as a frequency-doubling device for the vacuum ultraviolet region.