Terahertz refractive index sensor based on Tamm plasmon-polaritons with graphene

A novel terahertz (THz) refractive index sensor based on Tamm plasmon-polaritons (TPPs), comprising a Bragg reflector and a graphene layer, is proposed. A semi-analytical transfer matrix method is used to study the proposed structure and its sensing performance. The sensor demonstrates a sensitivity of 0.744 THz per refractive index unit (THz/RIU), or equivalently, 175.5  μm/RIU, and a figure of merit of 10.33  RIU^-1 at the operating frequency of 1.132 THz. The effects of structural parameters on the sensing performance are studied, offering new methods for improving TPP-based sensors. The proposed approach is a simple and practical alternative to traditional, and often more complex, THz sensing approaches, due to the ease of excitation, which lifts the requirement of phase and polarization-matching devices such as polarizers, prisms, and gratings. The proposed structure is studied for gas sensing, and its performance is compared with previous THz refractive index sensing structures.