POLARITON EFFECTS IN MULTIPLE-QUANTUM-WELL STRUCTURES OF CDTE CD1-XZNXTE/

Strong effects of coupling between exciton and electromagnetic modes i n periodic multiple-quantum wells of CdTe/Cd0.87Zn0.13Te with the peri od equal to either one-half or one-fourth of the light wavelength in t he barrier material are experimentally demonstrated by means of reflec tivity studies. The measurements are performed for various thicknesses of the cladding layer, incidence angles, magnetic fields, and degree of disorder. Reflectivity spectra as well as energies and radiative li fetimes of the polaritonlike excitations are computed for the relevant structures. It is demonstrated that current theory describes quantita tively the main features of the reflectivity. For multiple-quantum wel ls with the period equal to one-half of the photon wavelength in the b arrier material a strong enhancement of the exciton-photon coupling is observed. This enhancement allows the detection in the frequency doma in of the modification of the radiative coupling due to the presence o f a dielectric mirror. A considerably different behavior of structures with the period equal to one-half and one-fourth of the light wavelen gth is predicted to show up in four-wave mixing time-resolved measurem ents. It is suggested that the description of the luminescence require s a thorough consideration of localization and thermalization dynamics .