355  nm ultraviolet laser output based on a PPMgLN crystal

This paper reports the method of generating a 355 nm ultraviolet (UV) quasicontinuous pulse laser by using two periodically poled Mg-doped lithium niobate (PPMgLN) crystals in a single-pass cascade. In the first PPMgLN crystal with a length of 20 mm and a first-order-poled period of 6.97 µm, the second-harmonic light of a 532 nm laser with 780 mW is generated from the 1064 nm laser with an average power of 2 W; After that, in the second PPMgLN crystal with a length of 15 mm and a third-order-poled period of 5.30 µm, the 532 nm laser generated was combined with the 1064 nm laser remaining through the first PPMgLN crystal to obtain a 355 nm UV laser with a maximum output average power of 20 mW, a repetition rate of 40 kHz, a pulse width of 49 ns, and a peak power of 10 W. Compared with existing reports, we have higher peak power and single pulse energy, which is an important application of the PPMgLN crystal. This paper will provide an important case for the realization of a 355 nm UV quasicontinuous or a continuous laser.