High Q multi fano resonance in metal–insulator–metal waveguide and its application in magnetic field sensing

Abstract

This article proposes a novel magnetic field sensor which combines a metal insulator metal (MIM) waveguide with a Fano resonance (FR) system, this design is capable of detecting the strength of an external vertical magnetic field through the movement of Fano spectral lines. The proposed FR system consists of a ring resonator, a square resonator, and a metal baffle. The Finite Difference Time Domain (FDTD) method is used to study the transmission and magnetic field distribution characteristics. Research has shown that by adjusting geometrical parameters such as the radius of the ring resonator, the coupling distance, and the edge length of the square resonator, the position and intensity of the FR can be effectively tuned. The simulation results show that the designed sensor exhibits high sensitivity in the magnetic field range of 0–350 Gs, with a maximum magnetic sensitivity of \(36.4{\kern 1pt} {\text{p}}m/Gs\) and Figure of Merit (FOM) of \(1.8 \times 10^{ - 3} Gs^{{{ - }{1}}}\). In addition, the resolution of the sensor reached \({0}{\text{.0275}}{\kern 1pt} G{\text{s}}\), indicated its good potential for sensing applications. The proposed Fano resonance magnetic field sensor is crucial for improving the performance of existing technologies, especially in magnetic field sensing across scientific, industrial, and technology.