Deep-UV nonlinear optical crystal KBe2BO3F2-discovery, growth, optical properties and applications

This review introduces in detail the history of the discovery of the nonlinear optical crystal KBe2BO3F2 (KBBF), with a full description of its growth, space structure, optical properties, and capability to generate deep-ultraviolet (UV) harmonic generation. Several important applications developed recently using all-solid-state deep-UV light sources, such as super-high-resolution laser photoemission spectrograph and 193 nm photolithography, will be reviewed.