Degenerate Band Edge and Stationary Inflection Point in Glide-Symmetric Double-Corrugated Waveguides

The presence of two kinds of higher-order degeneracy conditions in a type of glide-symmetric lossless and gainless double-corrugated waveguide is demonstrated. The waveguide, consisting of a rectangular cross-section loaded with metallic pillars arranged in a glide-symmetric configuration, exhibits high-order exceptional points of degeneracy (EPDs): the degenerate band edge (DBE) and the stationary inflection point (SIP). The influence of various geometrical parameters and losses on the waveguide’s dispersion is analyzed, and the corresponding complex dispersion diagrams are presented.