Efficient 2-W Average Power 206 nm Deep-Ultraviolet Generation from 100-kHz Picosecond Pulses

We report on the generation of 2W average power pulsed deep-ultraviolet radiation at 206 nm with few-picosecond pulse duration at a repetition rate of 100 kHz. The 206 nm radiation is derived in three steps by fifth harmonic generation from a 1030-nm, 1.6-ps Yb3+:YAG laser. The steps are second harmonic generation (SHG), fourth harmonic generation (FHG) and sum frequency generation (SFG), see Fig. 1 a). A nonlinear-optical beam flattening scheme together with group velocity matching by substantial pulse front tilts enable, to the author's best knowledge, a new world record in average output power and conversion efficiency.