Magnetic Fano resonance of heterodimer nanostructure by azimuthally polarized excitation.

Di Zhang,Hongfeng Liu,Qiaofeng Dai,Haiying Liu,Fu Deng,Haihua Fan,Jin Xiang,Min Ouyang

doi:10.1364/oe.25.026704

Abstract

The optical properties of a Si-Au heterodimer nanostructure, which is composed of an Au split nanoring surrounded by a Si nanoring with a larger diameter, are investigated both theoretically and numerically. It is found that a pure magnetic plasmon Fano resonance can be achieved in the Si-Au heterodimer nanostructure when it is excited by an azimuthally polarized beam. It is revealed that the pure magnetic Fano resonance is generated by the destructive interference between the magnetic dipole resonance of the Si nanoring and the magnetic dipole resonance of the Au split nanoring. A coupled oscillator model is employed to analyze the Fano resonance of the Si-Au heterodimer nanostructure. The pure magnetic response of the Si-Au heterodimer nanostructure is verified by the current density distributions and the scattering powers of the electric and magnetic multipoles. The Fano resonance in the Si-Au heterodimer nanostructure exhibits potential applications of low-loss magnetic plasmon resonance in the construction of artificial magnetic metamaterials.

Highlights

Fano resonance based on artificial plasmon structure has become the focus of research in recent years for its wide applications in the areas such as surface enhanced Raman scattering (SERS) [1], slow-light devices [2], biological and chemical sensors [3,4], optical switch [5,6], and plasmon ruler [7]
We investigated the optical properties of a Si-Au heterodimer nanostructure (Si-Au HDNS), which is composed of an Au split nanoring (Au SNR) surrounded by a Si nanoring (Si NR) with a larger diameter
The magnetic dipole mode is characterized by circular displacement currents on the Si NR, which is similar to that described for a silicon hollow nanodisk [37]

Summary

Introduction

Fano resonance based on artificial plasmon structure has become the focus of research in recent years for its wide applications in the areas such as surface enhanced Raman scattering (SERS) [1], slow-light devices [2], biological and chemical sensors [3,4], optical switch [5,6], and plasmon ruler [7]. Luk’yanchuk, “Generating and manipulating higher order Fano resonances in dual-disk ring plasmonic nanostructures,” ACS Nano 6(6), 5130–5137 (2012). “Double Fano resonances due to interplay of electric and magnetic plasmon modes in planar plasmonic structure with high sensing sensitivity,” Opt. Express 21(2), 2236– 2244 (2013).

Results

Conclusion