Polaritons: the electromagnetic modes of media

Abstract

A detailed discussion of the properties of bulk polaritons in an isotropic dielectric, with a single infrared active optical phonon is given. The phonon and photon strength functions, which provide a useful means of characterizing the polariton are introduced, and polaritons examined in magnetic crystals, anisotropic dielectrics, materials in which spatial dispersion effects and absorption are important. Experimental methods of studying polaritons are reviewed, with emphasis on Raman scattering, non-linear interactions between polaritons and recent experimental studies of non-linear optical phenomena where polaritons in the intermediate state play an important role. The properties of surface polaritons at the interfaces of the isotropic dielectric, anisotropic dielectrics and magnetic media, and experimental methods for the study of surface polaritons are also discussed. The paper concludes with the comparison between the properties of coupled magnon-phonon modes in magnetic crystals and polaritons.