Ultra-highly sensitive Fano resonator with dynamic tunability based on plasmonics

Abstract

A novel Fano resonator can be dynamically tuned as well as keep pretty high sensitivity at the same time. The Fano resonator is designed by a triangular ring-like cavity coupled with a metal–insulator–metal (MIM) waveguide, enabling it to resonant in the terahertz band. The device’s performance is analyzed using the finite element method (FEM), and its resonances are validated with multimode interference coupled-mode theory (MICMT). The simulation results show that triangular ring-like cavity structure coupled with the rectangular structure will excite two asymmetric Fano resonances. According to the Fabry–Pérot (FP) resonant theory, the Fano resonant frequency can be easily manipulated by changing the cavity structure parameters. In addition, by integrating graphene into the resonator, it is possible to significantly shift the Fano resonance peak by altering the Fermi energy level, reaching up to 229 GHz. The Fano resonators are also very sensitive to the medium they interact with, achieving a maximum figure of merit (FOM) of 25,853. Finally, the Fano resonator is applied in cancer cell detection to expand the detection band while maintaining accurate detection. The proposed resonator’s superior performance offers potential in medium detection, narrowband filtering, and frequency selection, etc.