Self-referenced Terahertz Optical Sensor with Dirac Semi-metal and Topological Photonic Crystal

In recent years, the research on tunable terahertz devices has drawn significant attention. This article presents a novel optical sensor consisting of bulk Dirac semi-metal and topological photonic crystals. The numerical simulation results reveal that the Tamm plasmon state and topological edge state cause multi-mode absorption. It is found that one of the modes remains unaffected while other modes experience significant change by altering the analyte refractive index. Taking advantage of this, a self-referenced refractive index sensor with a sensitivity of 0.365 THz/RIU and FOM, 717 RIU-
¹
is proposed. The tunability of the device with Fermi energy and the thickness of Dirac semi-metal has also been established.