Air lasing: Phenomena and mechanisms<xref rid="cpb_28_11_114204fn1" ref-type="fn">*</xref><fn id="cpb_28_11_114204fn1"><label>*</label><p>Project supported by the National Natural Science Foundation of China (Grant Nos. 61625501, 61427816, and 11904121), the Open Fund of the State Key Laboratory of High Field Laser Physics (SIOM), China, the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT), China (Grant No. 2017TD-21), and Fundamental Research Funds for the Central Universities of China.</p></fn>

Air lasing: Phenomena and mechanisms**

Project supported by the National Natural Science Foundation of China (Grant Nos. 61625501, 61427816, and 11904121), the Open Fund of the State Key Laboratory of High Field Laser Physics (SIOM), China, the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT), China (Grant No. 2017TD-21), and Fundamental Research Funds for the Central Universities of China.

Li Helong^{1, 2}, Yao Danwen², Wang Siqi², Fu Yao², Xu Huailiang^{2, 3, †}

(a) Schematic diagram of the polarization gating, where HWP stands for a half wave plate, and OA is the optical axis of the multiple order quarter wave plate (MQW) and that of the zero-order quarter wave plate (ZQW). The angle θ is the angle between the OAs of MQW and ZQW. (b) The intensity of the 391-nm lasing (filled red circle) and that of the 391-nm fluorescence (open green circle) induced by the polarization-modulated pulses.^[99]