Transformation of the spectrum of a femtosecond laser pulse during propagation in the atmosphere
V.E. Prokop’ev1,2, D.M. Lubenko1,3
1High Current Electronics Institute of the Siberian Branch of the RAS, Tomsk, Russia
2National Research Tomsk State University, Tomsk, Russia
3National Research Tomsk Polytechnic University, Tomsk, Russia
Keywords: femtosecond laser, ultrashort laser pulse, spectrum broadening, simulated Raman scattering, four-wave parametric process
Abstract
Experimental results and the analysis of the reasons for the transformation of spectral parameters of a femtosecond laser pulse propagating in atmosphere and in pure molecular nitrogen are presented. The experiment was carried out under aberration focusing conditions. It is shown that the main contribution to the anti-Stokes spectrum broadening is made by cascade parametric four-wave mixing initiated in the filamentation domain by stimulated Raman Stokes scattering on rotational transitions of nitrogen.
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