Multi-beam laser processing is a very popular method to improve processing efficiency. For this purpose, a compact and stable multi-beam pulsed 355 nm ultraviolet (UV) laser based on a micro-lens array (MLA) is presented in this Letter. It is worth noting that the MLA is employed to act as the spatial splitter as well as the coupling lens. With assistance of the MLA, the 1064 nm laser and 532 nm laser are divided into four sub-beams and focused at different areas of the third-harmonic generation (THG) crystal. As a result, the multi-beam pulsed 355 nm UV laser is successfully generated inside the THG crystal. The measured pulse widths of four sub-beams are shorter than 9 ns. Especially, the generated four sub-beams have good long-term power stability benefitting from the employed MLA. We believe that the generated stable multi-beam 355 nm UV laser can meet the requirement of high-efficiency laser processing, and the presented method can also pave the way to generate stable and long-lived multi-beam UV lasers.

轨道角动量（OAM）涡旋光是一种具有相位孤立奇点的光场，其相位波前呈螺旋分布，光场复振幅包含螺旋相位项exp(ilθ)。近年来，OAM涡旋光被广泛地应用在光学操控、成像、通信、传感等方面。超短脉冲OAM涡旋光同时具有涡旋光和超短脉冲的优点，可应用于手性材料加工、远距离传输、强场物理研究，非线性频率转换研究等方面。通过激光器直接产生OAM涡旋光具有系统整体简便性高和光束质量好等优势，对国内外基于有源方法产生超短OAM涡旋光的方法进行了总结。目前，通过有源方式产生的超短OAM涡旋光的脉冲宽度还局限于几百飞秒，如何通过直接输出的方法获得百飞秒以内甚至是少周期脉冲涡旋光输出将是未来研究的一个重要方向。