Interference between stimulated Raman scattering and self-phase modulation in pressurized methane in highly transient femtosecond pump regime

The mutual interference between the transient stimulated Raman scattering and the self-phase modulation was considered a long time ago [Phys, Rev. A 2 (1970) 60]. In this work we have studied experimentally, for the first time to our knowledge, the influence of the transient stimulated Raman scattering on the self-phase modulation, considering single-shot Raman spectra, The stimulated Raman scattering was excited in methane by 140 fs pulses of the fundamental wave of a Ti:sapphire laser. Narrowing of the Stokes spectrum and suppression of the self-phase modulation structure were observed with increasing Raman gain, in agreement with the theoretical predictions. The effect has been observed up to 40 atm of methane pressure, (C) 2000 Elsevier Science B.V. All rights reserved.