Topologically originated optical analog of electromagnetically induced reflectance in Dirac semi-metal based photonic structure

Abstract

The optical analog of the electromagnetically induced reflectance (EIR) effect was theoretically studied in an active topological photonic structure comprising Dirac semi-metal and topological photonic crystal. The destructive interference between the optical Tamm state and topological edge state results in an induced reflection. It was known that the EIR-like effect occurs in a system having a radiative state and a metastable state. Topological protection is used here to achieve a metastable state, so an effective design of the EIR-like effect was possible. The observed EIR-like effect was modeled as a coupled oscillator system. The use of bulk Dirac semi-metal makes this an active photonic system at terahertz frequencies where the Fermi energy can act as a tunable and controlling parameter through which the induced transparency can be varied.