Wave properties of surface polaritons in the dielectric–high-temperature superconductor–dielectric structure

The specific features of the surface polariton propagation in the dielectric–high-temperature superconductor–dielectric symmetric structure have been investigated in the temperature region $T < T_c/2$, where the structure can be considered as non-absorbing. It has been shown that the dispersion curves contain two polariton branches, i.e., high-frequency and low-frequency ones, which correspond to symmetric and antisymmetric distributions of transverse components of the wave field. For the high-frequency branch, there is a propagation constant range where the group velocity and energy flux directions are opposite to the phase velocity direction. In this range, a significant deceleration of polariton waves is also observed.