All Dielectric High Q-Factor Metasurface Refractive Index Sensor Based on Dual Fano Resonances in THz Region

In this letter, we propose an all-dielectric metasurface refractive index (RI) sensor driven by dual Fano resonances. The proposed sensor exhibits remarkable characteristics, including high sensitivity, large quality factor (Q), and significant figure of merit (FOM) simultaneously. The transmission spectra and field profile of the designed metasurface have been evaluated in order to do the analysis of Fano resonance. The Q factor for the corresponding resonance mode
${{f}_1}$
= 1.79 THz and
${{f}_2}$
= 3.90 THz are 920.00 and 685.53, respectively. It is also reported that the transmission properties are very sensitive to the surrounding RI. The FOM of the proposed device are 514.40/RIU and 351.55/RIU, and its sensitivity are 1000 and 2000 GHz/RIU, respectively, for the resonant frequencies
${{f}_1}$
and
${{f}_2}$
. It is noteworthy that by adjusting the thickness of the Si-bars (
${{t}_2}$
), the Q factor for
${{f}_2}$
-mode can be tune from 685.53 to 4409.00. This showcases the versatility of the proposed design, making it a promising tool for various sensing applications.