Augmented coherent anti-Stokes Raman spectroscopy linewidth parameter from laser-mode structure

Abstract

Because the modes of the pump, Stokes, and anti-Stokes spectra in even low-intensity multimode coherent anti-Stokes Raman spectroscopy (CARS) experiments do not have the same widths, the relation among the spectral profiles with unresolved modes differs from the relation among the exact spectra by having a linewidth parameter for the third-order susceptibility that is augmented by the sum of the laser-mode widths. For gaseous media, whose Raman bands have closely spaced lines with widths comparable to some laser-mode widths, this parameter can be determined primarily by the apparatus, simplifying interpretation of CARS spectra.