ADDITIONAL ELECTROMAGNETIC-WAVES AND STIMULATED LIGHT-SCATTERING IN THE VICINITY OF AN EXCITONIC RESONANCE

The excitation of additional waves caused by a spatial dispersion tran sforms the stimulated Raman and Brillouin scattering in the vicinity o f the excitonic resonance into a kind of a four-wave mixing. The param etric coupling of four exciton polariton waves (EPW's) on the nonlinea r polarization caused by the nonlinear polariton-phonon interaction re sults in the amplification of the Stokes additional wave. The Raman an d Brillouin gain coefficients of the Stokes waves depending on the amp litudes and the wave vectors of both pumping EPW's essentially differ from the ones in the case without additional waves. The nonlinear Rama n or Brillouin polarization containing additional waves generates a sp ectrum of scattered harmonics which consists of 20 harmonics with the combination wave vectors and frequencies instead of one anti-Stokes wa ve and one wave with the frequency lower than the Stokes frequency in the case without additional waves. The results obtained show that stim ulated light scattering can be an effective method for the experimenta l investigation of additional waves and additional boundary conditions due to the amplification of additional waves.