ENERGY-TRANSFER BETWEEN ELECTROMAGNETIC MODES NEAR THE ISOTROPIC POINT IN CDS

We investigate theoretically the coupling between the ordinary and extraordinary beam in CdS which can be caused by external perturbations of the crystal symmetry and manifests themselves by non-diagonal elements of the susceptibility tensor. The theory based on Stahl's coherent band-gap dynamics yields the dispersion relation for the two waves propagating in the crystal. The dispersion establishes a relation between microscopic band structure parameters and macroscopic wave vectors and determines the diagonal elements of the susceptibility. The transmission problem is solved exactly by means of the classical electrodynamics. The obtained formulas contain a fit parameter related to a non-diagonal element of the susceptibility tensor which can be determined by fitting measured spectra around the isotropic point. © 1989.