Highly efficient continuous-wave single-pass second-harmonic generation using multicrystal scheme

We report a simple, compact and novel implementation for single-pass second-harmonic-generation (SP-SHG) of continuous-wave laser radiation based on a cascaded multi-crystal scheme, which can provide the highest conversion efficiency at any given fundamental power. By deploying a suitable number of identical 30-mm-long MgO:sPPLT crystals in a cascade, and a 30-W cw Yb-fiber laser at 1064 nm as the fundamental source, we demonstrate SP-SHG into the green with a conversion efficiency as high as 56% in the low as well as high-power regime, providing a 5.6 W of green output for 10 W and 13 W green output for 25.1 W of input pump power. The multi-crystal scheme permits substantial increase in cw SP-SHG efficiency compared to the conventional single-crystal scheme, without compromising performance with regard to power stability and beam quality.

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