Surface electromagnetic waves in bounded periodic structure near the exciton bands

We solve the problem of surface electromagnetic waves (SEW) propagation in layered periodic structures, which contain layers with excitons, near the exciton bands in the terahertz wavelength range. The dispersion properties of electromagnetic waves for infinite and for bounded periodic structures are considered. We study the possibility of existence of SEW that can propagate along the surfaces of the bounded periodic pattern in areas forbidden for the propagation of electromagnetic waves. With the help of complex Poynting theorem it is shown that the considered SEW can exist independently or simultaneously on each surface of the structure. Obtained results make it possible to analyze the features of the surface, attached to a periodic pattern. This allows studying the quality of thin films on solid surfaces, the surfaces of biological materials, etc.