Highly efficient 355 nm UV generation with non-collinear phase-matching by a prism-coupled device based on CsLiB6O10

We report 355 nm third-harmonic generation (THG) of UV light using CsLiB6O10 (CLBO). To compensate for the walk-off angle in THG by Type II CLBO, we designed a prism-coupled device that takes advantage of non-collinear phase-matching. This new device, equipped with a Nd:YVO4 laser source, achieved THG with 1.86 W at 47.6% conversion efficiency from the second-harmonic input. This result marks a 1.43-fold improvement over a conventional CLBO crystal, thus validating the effectiveness of the design for walk-off compensation in Type II THG. This is also the first time THG has been achieved using CLBO.