Sum frequency generation of CW deep-UV lights using an external cavity with dual wavelength enhancement

We have developed an all solid-state coherent light source, which can generate 252.41 nm light. The developed laser system consists of two-stage external cavities. In this study, we report the output performance of the 2nd stage external cavity in this laser system. The output beam (373 nm) from the 1st stage and a single-mode CW Ti:sapphire ring laser (780 nm) are delivered into the BBO-installed external cavity to resonate both light to the cavity simultaneously, which make the power of each light in the cavity increased, so that we can obtain 252.41 nm light efficiently by sum-frequency mixing with a BBO crystal.