Minimization of the response time of a 20 W deep-ultraviolet light at 266 nm during intermittent operation

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 LiB 3 O 5 crystal and a CsLiB 6 O 10 (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.