Embedded waveguide band: New localized states from parity-time symmetric photonic crystal waveguide

Abstract Using conventional photonic crystal waveguides combined with the Parity-Time (PT) symmetry configuration, we study the evolution of the waveguide mode bands, and the mechanism of the band merging and the exceptional point forming. A special waveguide mode band occurs in the band evolution with a part of the band embedded in the bulky bands. The embedded band takes on a new localized state with its mode field is mainly localized in the waveguide. The frequency on the bottom of the embedded band excites a huge localized field. The exceptional point on the special band excites an asymmetric mode field in the waveguide and an amplified transmission.