We report 10,000-hour stable operation of a 266-nm picosecond laser with an average power of 20 W. We have developed a narrow-linewidth, high-peak-power 1064-nm laser source with a repetition rate of 600 kHz, an average power of 129 W, a linewidth of 0.15 nm, and a pulse duration of 14 ps using a gain-switched DFB-LD as a picosecond pulse seed source and a four-stage power amplifier with an Nd:YVO4 crystal. A 266-nm laser with a maximum average power of 25.4 W was generated by frequency conversion using LBO and CLBO crystals and had a pulse duration of 8 ps and beam quality factor of 1.5 at 20W. To the best of our knowledge, we also demonstrated that the average power and the beam quality can be maintained for 10,000 hours for the first time. We have confirmed the durability of the developed deep ultraviolet laser for industrial applications.

We demonstrated stable intermittent operation of a 266-nm picosecond pulsed light source with an average power of 20 W. The 266-nm beam, which had a maximum average power of 35.5 W, was generated by frequency conversion of a 1064-nm laser with an LiB3O5 crystal and a CsLiB6O10 (CLBO) crystal. The 1064-nm laser had a repetition rate of 600 kHz and an average power of 130 W and was capable of intermittent operation with an acousto-optic modulator in the fundamental laser section. By investigating the crystal temperature rise caused by the 266-nm light absorption in the CLBO crystal, we found that the crystal temperature rise caused by nonlinear absorption must be suppressed to achieve stable intermittent operation. The countermeasures allowed stable-intermittent operation at an average power of 20 W to be achieved, with a response time of 1.1 s for the 10%–90% rise conditions and a stability of 2%p-p for the average power fluctuation from 2 to 120 s. These results show that deep-ultraviolet picosecond pulses with an average power of 20 W can be used for industrial applications that require stable intermittent operation.