Theoretical performance analysis of cake-shaped terahertz sensor with three-band resonant absorption for self-referenced refractive index sensing

Our study proposes a cake-shaped terahertz self-referenced refractive index sensor, which combines Al and Al 2 O 3 and utilizes the metal-assisted guided-mode resonance (MAGMR) effect to synergistically enhance the surface plasmon resonance (SPR) of a two-dimensional grating, enabling the sensor to achieve strong absorption rates at three wavelength bands of 3.302 THz, 5.798 THz and 7.312 THz. In this study, the electric field strength and impedance matching of the three resonance peaks were analyzed, and the structural tolerance of the sensor was evaluated. At the same time, it highlighted the device’s outstanding sensing capability in response to variations in the refractive index of the surrounding medium. The sensitivity (S), full-width at half-maximum (FWHM), Q factor (Q), and figure of merit (FOM) were respectively optimized to 4.4 THz/RIU, 0.021 THz, 345.29 and 168.19 RIU -1 at the second and third resonance peaks. In the detection of various media in semiconductor and optoelectronic materials, the refractive index of various media typically varies in the range of 1.30-1.40. High-performance sensors demonstrate great potential value in this field.