Effect of the plasmon-phonon coupling anisotropy on the reflection coefficient of polar semiconductors ZnO and SiC-6H

We present some results of our investigations of the reflection coefficient in the IR spectral region for ZnO and SiC-6H crystals. We account for vibrations of three subsystems that are coupled in pairs, namely: (i) electromagnetic waves, (ii) optical lattice vibrations, and (iii) plasma oscillations of free charge carriers. It is shown that anisotropy of phonons and plasmons leads to a number of peculiarities in both the spectrum of coupled oscillations and transparency regions