Bao Mengyu, Zhao Zhifang, Wei Kai, Zheng Yongyue, Lu Bingheng, Xu Xiangjun, Luo Tianzhong, Teng Geer, Yong Jun, Wang Qianqian
Opt Express. 2024 Feb 12;32(4):4998-5010. doi: 10.1364/OE.513927.
Aiming to enhance the ns-LIBS signal, in this work, we introduced orbital angular momentum to modulate the laser phase of the Gaussian beam into the vortex beam. Under similar incident laser energy, the vortex beam promoted more uniform ablation and more ablation mass compared to the Gaussian beam, leading to elevated temperature and electron density in the laser-induced plasma. Consequently, the intensity of the ns-LIBS signal was improved. The enhancement effects based on the laser phase modulation were investigated on both metallic and non-metallic samples. The results showed that laser phase modulation resulted in a maximum 1.26-times increase in the peak intensities and a maximum 1.25-times increase in the signal-to-background ratio (SBR) of the Cu spectral lines of pure copper for a laser energy of 10 mJ. The peak intensities of Si atomic spectral lines were enhanced by 1.58-1.94 times using the vortex beam. Throughout the plasma evolution process, the plasma induced by the vortex beam exhibited prolonged duration and a longer continuous background, accompanied by a noticeable reduction in the relative standard deviation (RSD). The experimental results demonstrated that modulation the laser phase based on orbital angular momentum is a promising approach to enhancing the ns-LIBS signal.
为了增强纳秒激光诱导击穿光谱（ns-LIBS）信号，在本工作中，我们引入轨道角动量将高斯光束的激光相位调制为涡旋光束。在相似的入射激光能量下，与高斯光束相比，涡旋光束促进了更均匀的烧蚀和更多的烧蚀质量，导致激光诱导等离子体中的温度和电子密度升高。因此，ns-LIBS信号的强度得到了提高。基于激光相位调制的增强效果在金属和非金属样品上均进行了研究。结果表明，对于10 mJ的激光能量，激光相位调制使纯铜的铜光谱线峰值强度最大增加1.26倍，信号背景比（SBR）最大增加1.25倍。使用涡旋光束时，硅原子光谱线的峰值强度提高了1.58 - 1.94倍。在整个等离子体演化过程中，涡旋光束诱导的等离子体持续时间延长，连续背景更长，同时相对标准偏差（RSD）显著降低。实验结果表明，基于轨道角动量调制激光相位是增强ns-LIBS信号的一种有前景的方法。
