Magnetic field sensor based on multiple Fano resonance in metal-insulator-metal waveguide coupled with cross-shape resonator

In this paper, an innovative plasmonic magnetic fi eld sensor ( MFS ) that exploits a Metal-insulator- Metal ( MIM ) waveguide configuration with an asymmetric cross-shaped resonator is constructed. The design enables the observation of double Fano resonance in the transmission spectrum, resulting from the coupling between continuous spectrum and discrete spectrum. By incorporating magnetic fl uid in the asymmetric cross-shape resonator, the Fano line shapes can be tuned by the external magnetic fi eld. Finite-Difference Time-Domain ( FDTD ) is used to simulate the spectra response to external magnetic fi elds and geometrical sizes. The proposed structure exhibits remarkable magnetic fi eld sensitivity of 12.1 pm/Oe within the detection range of 15 Oe to 199 Oe . The resolution of MIM magnetic fi eld sensors can reach 0.0826 O e. The optimal fi gure of merit ( FOM ) and maximum Q factor of the Fano dip are about 6.9 x 10(-4)/ Oe and 66.74, respectively. Meanwhile, The proposed Fano resonance MFS has some advantages, including compact size, high sensitivity, and costeffectiveness. A strong linear relationship between the magnetic fi eld and resonance wavelength indicates that the proposed structure can fi nd potential applications in diverse fi elds such as magnetic fi eld sensors, aircraft navigation, and even nuclear energy generation.