Stimulated Raman amplification in compressed methane is studied under transient excitation conditions. Experimental studies with nearly transform-limited 1-ps pump pulses at 395 nm are accompanied by theoretical modeling, taking into account the depletion of the pump as well as the dispersion of the gas. Energy-conversion efficiencies as high as 47% to the amplified first Stokes component are achieved. For obtaining maximum efficiency, it is necessary to adjust the time delay between the pump and the seed pulses. Optimum time delay and its sign depend on the pump energy. It is shown theoretically that amplification is favorably affected by a pronounced group-velocity mismatch between the pump and the amplified Stokes pulses due to high dispersion.
© 2005 Optical Society of America
(190.0190) Nonlinear optics : Nonlinear optics
(190.2620) Nonlinear optics : Harmonic generation and mixing
(190.2640) Nonlinear optics : Stimulated scattering, modulation, etc.
(190.5650) Nonlinear optics : Raman effect
(190.5890) Nonlinear optics : Scattering, stimulated
Alexander I. Vodchits, Alexander G. Shvedko, Valentin A. Orlovich, Valery P. Kozich, and Wolfgang Werncke, "Stimulated Raman amplification of ultrashort seed pulses in compressed methane," J. Opt. Soc. Am. B 22, 453-458 (2005)