Extracavity third-harmonic generation at 213nm of a passively Q-switched Pr:YLF laser

We report on short pulse deep ultraviolet laser from an extracavity third harmonic generation passively Q-switched (PQ) Pr:YLF laser operating at 213nm. By compensating the thermal lens effect of the laser crystal, optimizing the cavity length and utilizing Co:MgAl ₂ O ₄ (MALO) as the saturable absorber, we obtain the highest pulse output power at 213nm from a PQ Pr:YLF laser. Under pumping with a fiber coupled blue laser diode array, we realized 11.87ns pulses at a repetition rate of 15KHz from a 7.5mm long cavity at an average output power of 53.1mW at 213nm. This is the highest PQ pulse deep UV at 213nm generated by extracavity third harmonic generation of a passively Q-switched Pr:YLF laser.