Monolithic wavelength converter for ultraviolet light by use of a GdxY1-xCa4O(BO3)3 crystal

GdxY1-xCa4O(BO3)3 (GdYCOB) is a promising nonlinear optical crystal that shows high effective nonlinearity deff, noncritical phase matching, and high chemical stability. We report on the fabrication and characteristics of a monolithic wavelength converter, which generates ultraviolet light by the incidence of a 1.064 ?m near-infrared laser. The converter consists of GdYCOB for third-harmonic generation, KTiOPO4 (KTP) for second-harmonic generation, and a wave plate. GdYCOB has the advantage of an extremely wide angular acceptance bandwidth, whereas KTP exhibits a high effective nonlinear coefficient and a broad temperature bandwidth. Consequently the combination of these crystals results in highly efficient and stable ultraviolet conversion for constructing a compact and robust ultraviolet laser.