High-performance terahertz refractive index sensor based on a hybrid graphene Tamm structure

Abstract

In recent years, the research on tunable and high-performance terahertz devices has attracted widespread attention. In this paper, we propose a novel refractive index sensor consisting of monolayer graphene and multilayer photonic crystal with a defect layer. It is found that Tamm plasmon polaritons can be excited at the top graphene interface, which can strongly interact with the defect mode in this coupled structure. The results of numerical simulation demonstrate that the coupling can be either tuned by adjusting the geometric parameters or actively controlled by the chemical potential in graphene as well as the incident angle of light, allowing for tunable dual-band perfect absorption with strong interaction. Moreover, the resonance frequency of the defect mode is sensitive to the changes of the ambient refractive index. The sensitivity and figure of merit of this device as a sensor can reach 1.01 THz per refractive index unit (THz/RIU) and 631.2 R I U − 1 , respectively. In addition to high performance, the sensor does not require phase- or polarization-matching devices, paving the way for the research of optical devices.