全固态皮秒径向偏振激光器及其加工特性

All-solid-state picosecond radially polarized laser and its processing characteristics

在自主研制的全固态皮秒激光器基础上,腔外加入偏振转换元件输出皮秒径向偏振激光,并对其进行侧泵Nd:YAG晶体放大,最终得到中心波长1 064 nm、平均功率1.95 W、重复频率1 kHz、峰值功率1.77×108 W、光束质量2.95以及纯度92%的皮秒径向偏振激光器。用该激光器对0.5 mm厚不锈钢材料进行钻孔和刻槽实验,并与同等加工工艺参数条件下皮秒线偏振激光器钻孔圆度和刻槽深度进行对比,分析两种激光器对加工效果的影响。实验结果表明,相比皮秒线偏振激光,利用皮秒径向偏振激光进行加工,钻孔圆度更好、刻槽深度更深且槽侧壁更为平坦。该结果为皮秒径向偏振激光器在材料加工领域的应用提供参考。

An average power of 1.95 W picosecond radially polarized laser was obtained with 1 064 nm at 1 kHz, which based on an all-solid-state picosecond laser developed independently. The peak power of the radially polarized beam was up to 1.77 ×108W and the beam quality was measured to be M2=2.95 with the pulse width 11 ps, corresponding to the beam purity of 92%. The radially polarized seed beam was obtained by adding the polarization conversion element outside the laser cavity. In addition,the modulation attenuator caused two different polarization lasers to output the same optical power and then enter the subsequent optical system;and a 0.5 mm thick stainless steel was drilled and grouted by using the obtained picosecond radially polarized laser and picosecond linearly polarized laser under the same processing parameters, respectively. The difference on the circularity of the holes and the depth of the grooves were compared with each other when it was processed by the two polarized picosecond lasers. The results show that the picosecond radially polarization laser has better drilling roundness,deeper notch depth and flatter sidewall of the groove compared to the picosecond linear polarization laser processing results. This results provides a reference for the application of picosecond radial polarization laser in the field of material processing.