Lu Xu, He Siyi, Xue Pengyu, Chen Yewei, Zhang Ning, Wen Yajing, Li Zihan, Wang Quanjun, Yao Jinping
State Key Laboratory of Ultra-intense Laser Science and Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Adv. 2025 Sep 26;11(39):eady7458. doi: 10.1126/sciadv.ady7458.
Air lasing initiated by femtosecond laser filamentation holds exciting prospects for remote sensing. However, low output energies restrict its practical applications. We demonstrate a cascaded amplification strategy that breaks this critical barrier. By implementing quadruple-pass focusing of 5.7-millijoule, 800-nanometer femtosecond pulses in nitrogen, we achieve a 40-fold enhancement in the energy of [Formula: see text] lasing, yielding an output of approximately 4.4 microjoules. This multipass configuration also reduces the lasing threshold by nearly 70%, facilitates spectral broadening of pump pulses, and compresses the pulse duration of [Formula: see text] lasing. Capitalizing on these combined effects, we developed a single-beam coherent Raman spectroscopy, which enables simultaneous detection of multiple species and exhibits high sensitivity at the parts-per-million level. This work successfully addresses the energy bottleneck of air lasing using only commercially available femtosecond lasers and provides a promising approach for standoff chemical analysis.
由飞秒激光丝化引发的空气激光在遥感领域具有令人兴奋的前景。然而，低输出能量限制了其实际应用。我们展示了一种级联放大策略，突破了这一关键障碍。通过在氮气中对5.7毫焦、800纳米的飞秒脉冲进行四重聚焦，我们实现了[公式：见正文]激光能量增强40倍，输出约4.4微焦。这种多程配置还将激光阈值降低了近70%，促进了泵浦脉冲的光谱展宽，并压缩了[公式：见正文]激光的脉冲持续时间。利用这些综合效应，我们开发了一种单光束相干拉曼光谱，能够同时检测多种物质，并在百万分之一水平上表现出高灵敏度。这项工作仅使用市售飞秒激光成功解决了空气激光的能量瓶颈问题，并为远距离化学分析提供了一种有前景的方法。
