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 lasing emissions from the 1 bar of N₂ and 5 bars of Ar mixture induced by filamentation of mid-infrared, 4 μm wavelength pulses at a distance above 2 m, and (b) excitation and energy-level diagram of the backward ASE-type N₂ lasing.^[41]