Tunable Magnetic Fano Resonances on Au Nanosphere Dimer–Dielectric–Gold Film Sandwiched Structure

Abstract

The Fano resonance demonstrates excellent performance due to its narrow asymmetrical spectral line shape, and its sensitivity to structure and material parameter changes. Compared to conventional Fano resonances, the Fano resonance generated by the magnetic dipole is more advantageous because of its high absorption and low loss. In this study, we propose an Au nanosphere dimer–dielectric–gold film sandwiched structure that supports the magnetic Fano resonance mode. And the Fano resonance can be efficiently tuned from visible to near-infrared wavelength by changing the size of the gold nanospheres and the thickness of the dielectric layer. Different from the single gold nanosphere–dielectric–film structure, the results suggest that the proposed structure is sensitive to the polarization direction of the excitation light. Considering the above characteristics, the proposed structure can be applied in multi-band sensing, surface-enhanced Raman spectroscopy, and dynamically adjustable optical switches.

Magnetic Concentric Hot-Circle Generation at Optical Frequencies in All-Dielectric Mesoscale Janus Particles

“…The interference of the magnetic and electric modes in such nanoparticle assemblies gives rise to sharp magnetic Fano resonances [11][12][13][14]. Dielectric wavelength-scaled (mesoscale) particles with a Mie-sized parameter q = kR, where k is the wavenumber and R represents particle radius, to the order of q ~10 have aroused big interest because of their potential to localize light at the sub-wavelength scale [15,16] and because of their ability to yield high internal magnetic and electric local field enhancements instead of plasmonic metal nanoparticles [17][18][19]. Moreso, the employment of mesoscale dielectric particles has facilitated the achievement of the remarkable magnetic enhancement of overcoming the inherent losses of plasmonic materials.…”