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) Spectra of backward N₂ emission for the circular (red) and linear (black) laser polarizations, at 9.3-mJ pulse energy, (b) the 337-nm emission signal vs. the rotation angle of the quarter wave plate, where the angle 0° corresponds to linearly polarized light.^[44] (c) and (d) Calculated electron energy distributions in the cases of (c) linearly and (d) circularly polarized laser pulses at the laser intensity of 1.4 × 10¹⁴ W/cm².^[46]