Generation of 266 nm continuous-wave with elliptical Gaussian beams

The 266 nm continuous-wave coherent radiation is generated by the second harmonic generation of a β-BBO crystal placed inside an external enhancement cavity. Its fundamental beam is a 532 nm laser from commercial production of Coherent Company. Impact of focusing shape of the crystal on the conversion efficiency is simulated detailedly. Theoretical and experimental results show that the elliptical focusing can decrease the walk-off effect and improve conversion efficiency of the second harmonic generation (SHG). We obtain experimentally the 266 nm radiation output of 180 mW with elliptical focusing in a BBO crystal using bowtie cavity when the fundamental wave input 1 W . The SHG conversion efficiency reaches 18%.