Improved Sellmeier Equations and Phase-Matching Characteristics in Deep-Ultraviolet Region of ${\hbox {KBe}}_{2}{\hbox {BO}}_{3}{\hbox {F}}_{2}$ Crystal

A 3.0-mm-thick KBe
₂
BO
₃
F
₂
(KBBF) crystal has been successfully grown and used to fabricate a right angle prism. Its refractive indices were accurately measured with a prism technique at seven wavelengths from 0.4047 to 0.6562 mum . Its phase-matching characteristics in deep-ultraviolet (UV) region were investigated. Using the measured indices and phase-matching angles from deep-UV to near infrared, improved Sellmeier equations for KBBF have been derived.