Effects of Laser Linewidth on the Coherent Anti-Stokes Raman Spectroscopy Spectral Profile

Abstract

The expression for the intensity in coherent anti-Stokes Raman spectroscopy (CARS) was derived for scanning CARS by taking into account the linewidths and phase relation of the two laser beams, and simulation procedures suited for practical applications were developed. The CARS spectra of p-xylene and N 2 gas were observed, and the results were compared with the simulation curves based on two extreme cases of the statistical property of the laser source. It was shown that the effect of laser linewidth becomes remarkable when the Raman linewidth is comparable to or smaller than the laser linewidth, and that the degree of coherence among the frequency components within the laser linewidth is an important factor in determining the spectral profile.