High Sensitivity Quadrupole Fano Resonances Using Terahertz Metamaterials with Its Application as Biosensor

Artificially designed plasmonic metamaterials have achieved low loss and high Q-factor quadrupole Fano resonances in terahertz imaging, spectroscopy and biosensing. In this paper a planar terahertz Fano resonance metamaterial structures with tiny asymmetry is designed to optimize structural parameters with its potential transmission properties. We managed to suppress irregular reflection peaks at the frequency of 1.15 THz to 1.50 THz by optimizing the thickness of the silicon substrate to 100 \mu \mathrm{m}. Simulation result shows that the optimization can be achieved when the lower gap displacement from the center is of 2 \mu\mathrm{m}, the width of gap arm is of 3 \mu \mathrm{m}, and the width of metallic aluminum layer is of 6 μm. Moreover, when the different dielectric sample (e.g., the dielectric constant \varepsilon varies between 20 to 80) is covered on the surface of the structure inside the Fano ring with thicknesses from 0.1 \mu \mathrm{m} to 0.4 μm, the frequency of the quadrupole resonance will shift about 20-40 GHz with almost linear trend. Thus, the proposed metamaterial structure may have the extensive applications such as high sensitive biosensor to identify trace substances in the fields of terahertz research in future.