RESONANCE CARS IN NARROW-GAP SEMICONDUCTORS

Coherent anti-Stokes Raman scattering due to spin transitions of free carriers in narrow gap semiconductors is discussed. The basic results of the electrodynamic theory of optical four-wave mixing and of the qu antum mechanical calculation of the third-order non-linear susceptibil ity chi((3)) are briefly reported in the context of the particular pro perties of narrow gap semiconductors. The enhancement of the Raman-lik e resonances of chi((3)) for photon energies close to the fundamental gap is demonstrated and interferences of Raman and one-photon interban d transitions are discussed. Applications of the method to epitaxial f ilms of narrow gap semiconductors and to quantum well structures are p resented.