High sensitive refractive index sensor based on spatial symmetry breaking Fano metamaterials fabricated by ion beam irradiation

Abstract The sensitivity of plasmonic nanostructures based refractive index sensor can be improved by free-standing three-dimensional (3D) configuration. Here, by means of focused-ion-beam (FIB) induced folding technique, we fabricated arbitrary spatially oriented double-flake 3D metamaterials (MMs). The experimental measured sensitivity can reach 2703 nm/RIU, and based on the symmetry breaking configuration, the figure of merit (FoM) reaches 37.2 RIU−1 in simulation results. What's more, the different coupling mechanisms in our MMs enable the independent modulation of each resonance. This work opens up new avenues for near-field coupling modulation, holding great potential applications in multi-resonance differential sensing, switch devices and optical communication.