Brewster effect when approaching exceptional points of degeneracy: Epsilon-near-zero behavior

We reveal that the phenomenon of full plane-wave transmission without phase accumulation commonly associated with epsilon-near-zero (ENZ) materials does not require vanishing of permittivity. We theoretically connect the phenomenon with the condition of the Brewster effect satisfied at the edges of stop bands (at so-called exceptional points of degeneracy) and show that full transmission without phase accumulation can be observed in various one-dimensional periodic structures.

Particularly, exploiting the manifold of exceptional points of degeneracy in one-dimensional all-dielectric periodic lattices, we demonstrate that these structures not only offer a lossless and extremely simple, complementary metal-oxide semiconductor compatible alternative for some applications of ENZ media but exhibit new properties of all-angle full transmission with zero phase delay.

The main results of the study can be readily transferred to acoustic and matter waves.