Frontiers in Physics (Jan 2023)

Theoretical treatment on externally-seeded superradiance from N2+ in femtosecond laser filamentation in low-pressure nitrogen

  • Quanjun Wang,
  • Quanjun Wang,
  • Quanjun Wang,
  • Pengji Ding,
  • Shane G. Wilkins,
  • Michail Athanasakis-Kaklamanakis,
  • Michail Athanasakis-Kaklamanakis,
  • Yuxuan Zhang,
  • Zuoye Liu,
  • Bitao Hu

DOI
https://doi.org/10.3389/fphy.2022.1090346
Journal volume & issue
Vol. 10

Abstract

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We perform a theoretical investigation of a collective emission in tunnel-ionized nitrogen molecules triggered by a coherent seed pulse. A semiclassical theory of superradiance that includes the superradiant temporal profile, characteristic duration, time delay, intensity is achieved. The theoretical predictions of 391-nm forward emission corresponding to the transition between N2+(B2Σu+,ν′=0) and N2+(X2Σg+,ν=0) as a function of nitrogen gas pressure are compared with the recent experimental data [Ding P. Lasing effect in femtosecond filaments in air, Ph.D. thesis, Université Paris-Saclay (2016)]. The good agreement demonstrates that the time-delayed optical amplification inside the molecular nitrogen ions is superradiance.

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