Wave propagation collapse in the polariton negative dielectric band of crystal

Electromagnetic wave destruction due to photon-phonon interaction (polariton) in the negative dielectric band of crystal has been studied in our work. General case without low damping approximation is considered. Modeling results are obtained in analytical form based on single oscillator model. Phonon damping effects are analyzed using the new common technique of the phase portraits both for complex dielectric functions and for complex refractive index. The realization possibility for the wave penetration process in the negative dielectric region is estimated for the realistic MnF₂ crystal. It is shown the polariton wave in the negative dielectric area of real crystal should be quickly dissipated and moreover it may also cause the collapse of transmitted wave at the narrow crystal interface.