Group velocity-matched interactions in fs- nonlinear optics:enhanced high-order Raman scattering by impulsively excited vibrations

Summary form only given. We have recently proposed and demonstrated a new regime of fs-pulse stimulated Raman scattering (SRS). In this regime, the medium is prepared by an intense pump pulse with a duration shorter than the molecular vibrational period T/sub v/ = 2/spl pi///spl Omega//sub v/ (impulsive excitation). A low-intensity delayed injection pulse experiences phase modulation by the coherently oscillating vibrations, which leads to the generation of multiple sideband components /spl omega//sub n/ = /spl omega//sub 1/ + n /spl Omega//sub v/, (n = 0, /spl plusmn/1 ...). High efficiency of the side-band generation (up to 100%), tunability of the process, and the fact that the components are free of the influence of the deteriorating nonlinear effects (SPM, self-focusing etc.), suggest a wide range of potential applications of the technique in nonlinear optics and spectroscopy. The most intriguing feature of the SRS-regime is that the generated SRS-components are mutually coherent and can be used for the Fourier synthesis of sub-fs waveforms,,that has been recently demonstrated. In the paper we show that the scattering efficiency can be significantly increased by employing the dispersive properties of gas-filled hollow waveguides (HW).