Raman scattering by polaritons under nonstationary conditions. I: The basic principles of the general theory

Abstract

The fluctuation-dissipation method of theoretical investigation of stimulated Raman scattering (RS) by polaritons in piezoelectric crystals under nonstationary conditions taking into account both wave and local nonstationary cases in the fixed pump field approximation has been carried out. The method is based on solving the reduced operator equations in partial derivatives for Stokes and polariton fields coupled by the pump field. The equations contain the noise sourcespolariton fluctuations whose properties are defined by the fluctuation-dissipation theorem. The Stokes and polariton field are described in the quantum language as the operators in Heisenberg representation.Quantum description of fields is necessary for correct account of the initial fluctuations and is also essential for the right transition to the particular case of spontaneous RS. The energy characteristics, which describe the angular-frequency distribution of Stokes and polariton radiation are calculated by means of quantum statistical averaging of the corresponding field combinations. Their general connection with the correlative functions, which define initial and boundary field fluctuations is found. Raman Spectroscopy 3 (1975) 7-13. AN Rights Reserved Copyright 8 1975 by D. Reidel Publishing Company, Dordrecht-Holland Journal of