High-Power Narrow-Linewidth Q-Switched TEM00 Mode 355-nm Laser

We report on a high pulse energy, narrow-linewidth, Q-switched ultraviolet (UV) laser at 355 nm from the third harmonic generation (THG) of a 1064-nm Nd:YAG master oscillator power amplifier (MOPA) system. An output of 37 W at 355 nm was obtained with a pulse duration of 32 ns and a linewidth of similar to 2.5 pm. The beam-quality factor was measured to be M-2 = 1.24. This is, to the best of our knowledge, the highest average power for a Q-switched narrow-linewidth TEM00 UV laser at 355 nm. Meanwhile, a multimode laser rate equations model was used for theoretical analysis on the linewidth and pulse duration of the fundamental laser oscillator for the first time, and the calculated results agree well with the experimental data.