Frequency tripled semiconductor disk laser with over 0.5 W ultraviolet output power

Semiconductor disk lasers can produce high output power and good beam quality simultaneously. The high intracavity circulating power of about hundreds of watts, along with the flexibility of tailorable emitting wavelengths, make it an attractive light source for obtaining ultraviolet (UV) radiation from near-infrared lasers through nonlinear frequency conversion. This work reports a frequency tripled 327 nm semiconductor disk laser with record output power and wavelength tuning range by using a type-I phase-matched LiB₃O₅ (LBO) crystal and a type-I phase-matched β-BaB₂O₄ (BBO) crystal as the frequency-doubling and -tripling crystals respectively. Thanks to the obviously larger nonlinear coefficient of the type-I phase-matched BBO compared to the commonly used type-II phase-matched LBO, as well as the small spot size specifically designed at the crystal location, the maximum output power of UV lasers reaches 538 mW, corresponding to an optical-to-optical conversion efficiency from pump to UV laser of about 1.14%. A wavelength tuning range of about 8.6 nm and good power stability with a standard deviation of about 0.94 are also achieved.