Second harmonic generation of continuous wave ultraviolet light and production of β-BaB2O4 optical waveguides

We report on the generation of continuous-wave (cw) ultraviolet (UV) laser light at lambda=278 nm by optical frequency doubling of visible light in beta-BaB2O4 waveguides. Ridge-type waveguides were produced by He+ implantation, photolithography masking, and plasma etching. The final waveguides have core dimension of a few mu m(2) and show transmission losses of 5 dB/cm at 532 nm and less than 10 dB/cm at 266 nm. In our first experiments, a second harmonic power of 24 mu W has been generated at 278 nm in an 8 mm long waveguide pumped by 153 mW at 556 nm.