Supercontinuum of a 3.9-μ m filament in air: Formation of a two-octave plateau and nonlinearly enhanced linear absorption

Nikolay A. Panov, Daniil E. Shipilo, Vera A. Andreeva, Olga G. Kosareva, Alexander M. Saletsky, Huailiang Xu, Pavel Polynkin

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Through numerical simulations we reveal the scenario of 3.9-μm filament spectrum enrichment in the atmosphere in the cases of linear and circular polarization of the incident pulse. The discrete spectrum of odd harmonics transforms into the two-octave plateau in the case of linear polarization. In contrast, in the case of circular polarization of the incident pulse, the harmonic-free flat supercontinuum appears with the plasma onset, reaching the tenth harmonic of the input radiation. We identify the energy balance specific to the filamentation near 4 μm: the absorption on CO2 lines in the atmosphere is accelerated by the self-phase modulation in the Kerr nonlinearity early before the plasma channel is formed. This nonlinearly enhanced linear absorption overwhelms the plasma losses and conversion of the input pulse energy to the higher harmonics as well as the plateau.

Original languageEnglish (US)
Article number041801
JournalPhysical Review A
Volume94
Issue number4
DOIs
StatePublished - Oct 6 2016

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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