Flat-top beam deep-UV generation in CsLiB6O10 crystal

We present an experimental study on deep-UV (DUV) generation via second harmonic generation (SHG) utilizing a spatially uniform flat-top laser beam as an alternative to the conventional Gaussian beam. A commercial picosecond laser operating at 1064 nm in the TEMoo Gaussian mode was first frequency-doubled in a lithium triborate (LiB3O5, LBO) crystal. The resulting SHG beam were then converted into a flat-top profile using a refractive Gaussian-to-flat top beam shaper. This flat-top beam was subsequently frequency-doubled in a cesium lithium borate (CsLiB6O10, CLBO) crystal to directly generate fourth-harmonic DUV flat-top beams at 266 nm. A comparative experiment between DUV generation using Gaussian and flat-top beams was performed.