Abstract

Experiments have demonstrated the field-statistical effects due to fluctuations of the frequency-doubled, multimode pump laser fields on the intensities and the line shapes of molecular coherent anti-Stokes Raman spectroscopy (CARS) spectra.¹ The accuracy of CARS measurements on species concentrations and temperatures depends on properly accounting for these effects. Theoretical modeling using Gaussian¹ and squared-Gaussian² field-statistics has had only limited success. Since realistic laser field statistics can seldom be described accurately by any idealized models, we propose in this paper a general and systematic expansion of the field in terms of Gaussian and higher-order Gaussian field components. This approach is particularly well suited, to analysis of fields generated by nonlinear optical processes from Gaussian fields. We apply the theory to analyze the pump laser fields in the above CARS experiments. Our calculated results give much better agreement with experiments than previous theories.

© 1988 Optical Society of America