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 mu m/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. (C) 2019 Optical Society of America
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