An ultraviolet laser at 228 nm with adjustable repetition rate and narrow pulse width

Ultraviolet lasers play an important role in the study of ultraviolet resonance Raman spectroscopy. The Raman signals can be enhanced by the resonant Raman effect, thereby reducing the detection limit of Raman measurement. We focus on the study of a narrow -pulse all -solid-state ultraviolet laser with an output wavelength of 228 nm. The Nd:YVO4 is used as the gain medium and the electro-optic Q -switched cavity dumped technique is applied to achieve a fundamental frequency output of 914 nm in pulse width of several nanoseconds. Then, the second -harmonic light is generated by LiB3O5(LBO), and the fourth -harmonic 228 nm UV laser is obtained by beta -barium -borate (BBO) crystal. On this basis, further research has been conducted on the variation of fundamental and second harmonic laser power at different repetition rates. Due to the low gain of Nd:YVO4 at 914 nm, the average power of the laser is saturated and decreases with increased repetition rate. The output efficiency of UV laser is optimized by adjusting the focus lens. At the pump power of 30 W and the repetition frequency of 10 kHz, a 228 nm UV laser output with the highest average power of 84 mW is obtained. The UV laser is continuously adjustable within the range of 5-25 kHz repetition frequency and the pulse width is maintained at 2.8 to 2.9 ns, which meets the application requirements in the field of UV spectroscopy detection technology.