BULK AND SURFACE-POLARITONS IN SEMI-INFINITE SUPERLATTICES IN A MAGNETIC-FIELD - DISPERSION-RELATIONS, OPTICAL REFLECTION, AND ATTENUATED TOTAL REFLECTION

We calculate the dispersion relations for bulk- and surface-plasmon polaritions propagating in arbitrary directions in semi-infinite semiconductor superlattices under an external magnetic field applied parallel to the interfaces of the superlattice. We also calculate the reflectance and attenuated total reflection (ATR) spectrum, also for arbitrary angles, from such a structure. Under an applied magnetic field, the polariton modes that were pure s and p polarized without a field become mixed, and the frequency of the surface-polariton modes becomes nonreciprocal with respect to propagation direction. This nonreciprocity is easily seen in ATR probes. In addition, the reflectance calculation shows that the reflection coefficient is also nonreciprocal with respect to the angle of incidence in an applied field. This nonreciprocal reflection occurs in the absence of damping in the constituent films. We also demonstrate the existence of s-polarized surface-polariton modes in zero applied magnetic field and show that these surface modes couple only to an s-polarized driving field in an ATR experiment. The s-polarized mode exists only in the range where the thickness of the superlattice constituent films is on the order of the wavelength of the polaritons.