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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2504.18124 |
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| _version_ | 1866916707536207872 |
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| author | Yang, Wenli Li, Ping Yang, Luzhen Guo, Jianfeng Ding, Pengji Xue, Shan Du, Hongchuan |
| author_facet | Yang, Wenli Li, Ping Yang, Luzhen Guo, Jianfeng Ding, Pengji Xue, Shan Du, Hongchuan |
| contents | N$_2^+$ air lasing has attracted considerable attention due to its promising applications in remote sensing and the debates surrounding its generation mechanisms. Here, we present a comprehensive theoretical investigation of the role of molecular rotation in N$_2^+$ lasing at 391 nm ($B^2 Σ_u^+(v''=0)\rightarrow X^2 Σ_g^+ (v=0)$). By solving the open-system density matrix and Maxwell-Bloch equations in a rovibronic-state basis, we examine both the formation of the N$_2^+$ gain medium induced by a femtosecond pump pulse and the subsequent spatial propagation of the seed pulse. During the pump stage, rotational dynamics are found to significantly modify the angle-dependent populations of ionic vibrational-electronic states within tens of femtoseconds. Furthermore, ionization-produced rotational coherences substantially enhance the population inversion between the $X^2 Σ_g^+ (v=0)$ and $B^2 Σ_u^+(v''=0)$ states. In the seed propagation stage, both population inversion and rotational coherence are found to contribute to the lasing process, with the latter playing a dominant role in amplifying the lasing signals. These findings reveal the crucial role of molecular rotation in N$_2^+$ air lasing and highlight its potential as a tunable parameter for controlling lasing dynamics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_18124 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Influence of molecular rotation on the generation of N$_2^+$ air lasing Yang, Wenli Li, Ping Yang, Luzhen Guo, Jianfeng Ding, Pengji Xue, Shan Du, Hongchuan Optics N$_2^+$ air lasing has attracted considerable attention due to its promising applications in remote sensing and the debates surrounding its generation mechanisms. Here, we present a comprehensive theoretical investigation of the role of molecular rotation in N$_2^+$ lasing at 391 nm ($B^2 Σ_u^+(v''=0)\rightarrow X^2 Σ_g^+ (v=0)$). By solving the open-system density matrix and Maxwell-Bloch equations in a rovibronic-state basis, we examine both the formation of the N$_2^+$ gain medium induced by a femtosecond pump pulse and the subsequent spatial propagation of the seed pulse. During the pump stage, rotational dynamics are found to significantly modify the angle-dependent populations of ionic vibrational-electronic states within tens of femtoseconds. Furthermore, ionization-produced rotational coherences substantially enhance the population inversion between the $X^2 Σ_g^+ (v=0)$ and $B^2 Σ_u^+(v''=0)$ states. In the seed propagation stage, both population inversion and rotational coherence are found to contribute to the lasing process, with the latter playing a dominant role in amplifying the lasing signals. These findings reveal the crucial role of molecular rotation in N$_2^+$ air lasing and highlight its potential as a tunable parameter for controlling lasing dynamics. |
| title | Influence of molecular rotation on the generation of N$_2^+$ air lasing |
| topic | Optics |
| url | https://arxiv.org/abs/2504.18124 |