Tunable mid-infrared refractive index sensor with high angular sensitivity and ultra-high figure-of-merit based on Dirac semimetal

Abstract A tunable mid-infrared refractive index sensor consisting of bulk-Dirac-semimetal (BDS) and one-dimensional photonic crystals (1DPC) is proposed. This sensor has high angular sensitivity and ultra-high figure-of-merit (FOM), which is attributed to the optical Tamm states excited at the interfaces between BDS and 1DPC. Our numerical simulations show that the maximum value of the angular sensitivity and FOM of the sensor can reach up to 711.8°/RIU and 6001 RIU−1 respectively, which are much higher than those of the reported similar sensors. The simulations also demonstrate that the sensing performance can be adjusted by the Fermi energy and the structural parameters of the sensor. It is believed that, with the simple structure and the excellent performance, the proposed sensor has a broad application prospect in the field of biological detection.