The Plasmonic Fano Resonance Research Based On Heterogeneous Nanostructures

As a novel plasmonic phenomenon, Fano resonance has potential applications in chemical and biological sensing benefiting from sharp spectral features and extreme field localization at nanoscale. Although Fano resonance has gained a wide range of simulations in recent years, the Fano resonance in heterogenous nanostructures produced by bright and dark modes supported by different components has been seldom reported. The finite difference time domain (FDTD) Solutions software is utilized to theoretically simulate the plasmom’c Fano effect, and the main research and innovation details are as follows:A. The plasmonic coupling in heterogenous Al-Ag nanorod dimers is theoretically investigated. A pronounced Fano dip is found in the extinction spectrum produced by the destructive interference between the bright dipole mode from a short Al nanorod and the dark quadrupole mode from a long Ag nanorod nearby. This Fano resonance can be widely tuned in both wavelength and amplitude by varying the rod dimensions and end geometry, the separation distance and the local dielectric environment. The Al-Ag heterogeneous nanorod dimer shows a high sensitivity to the surrounding environment with a local surface plasmon resonance figure of merit of 7.0.B. Direct interference between the orthogonal electric and magnetic modes in a hybrid silicon-gold nanocavity is demonstrated to induce a pronounced asymmetric magnetic-based Fano resonance in the total scattering spectrum at near-infrared frequencies. Differing from the previously reported magnetic-based Fano resonances in metal nanoparticle clusters, the narrow discrete mode provided by the silicon magnetic dipole resonance can be directly excited by external illumination, and greatly enhanced electric and magnetic fields are simultaneously obtained at the Fano dip.In conclusion, the physical mechanism and near-field enhancement investigation of plasmonic Fano resonance in heterogenous nanostructures makes the Fano tuning more controllable and provides theory for the following experiments in plasmonic sensing and detection.