Enhanced Reflected Group Delay with Optical Tamm State via Graphene-Dielectric Bragg Mirror Configuration

Abstract

Group delay of the optical pulse reflected from the structure composed of graphene and one dimensional photonic crystal (1D PC) is studied. It is shown that the large negative group delay in this configuration can be realized due to the excitation of the optical Tamm state (OTS) at a graphene-dielectric interface. The reflected group delay can be enlarged negatively and can be switched from positive to negative or vice versa. We show that the conductivity of graphene has a significant influence on reflected group delay, making the graphene-PC structure be a good candidate for dynamic tunable optical delay device in the THz frequencies. Furthermore, the influences of the relaxation time of graphene, the incident angel, and the dispersion characteristics of top layer on group delay are clarified.

Enhanced and controllable reflected group delay based on Tamm surface plasmons with Dirac semimetals

“…[9] Therefore, researchers have investigated group delay enhancement and regulation in various structures. For example, the delay phenomenon in an analog circuit model, [10,11] photonic crystal (PC) structure [12] and Fabry-Perot cavity structures [13] has attracted extensive attention. In addition, Wang and Zhu studied the phenomenon of reflected optical pulse group delay of a weakly absorbing dielectric slab, and obtained a negative group delay of −4 ps.…”