Cavity modes and their excitations in elliptical plasmonic patch nanoantennas

Ayan Chakrabarty,Fred Minkowski,Qi-Huo Wei,Feng Wang,Kai Sun

doi:10.1364/oe.20.011615

Abstract

We present experimental and theoretical studies of two dimensional periodic arrays of elliptical plasmonic patch nanoantennas. Experimental and simulation results demonstrate that the azimuthal symmetry breaking of the metal patches leads to the occurrence of even and odd resonant cavity modes and the excitation geometries dependent on their modal symmetries. We show that the cavity modes can be described by the product of radial and angular Mathieu functions with excellent agreements with both simulations and experiments. The effects of the patch periodicity on the excitation of the surface plasmon and its coupling with the cavity modes are also discussed.

Highlights

Plasmonic nanoantennas have attracted significant attention in recent years due to their ability in coupling free space electromagnetic radiation into sub-diffraction limited volumes and vice versa based on the electrodynamics reciprocity [1, 2]
Recent studies show that the plasmonic patch antennas provide a new avenue towards various applications such as near perfect absorbers [18,19,20,21], single photon light sources by coupling them with quantum emission systems [22], metamaterials [23], and biosensors [24]
We present the physical understanding of the cavity modes and their excitation conditions for plasmonic patch nanoantennas in optical frequencies

Summary

Introduction

Plasmonic nanoantennas have attracted significant attention in recent years due to their ability in coupling free space electromagnetic radiation into sub-diffraction limited volumes and vice versa based on the electrodynamics reciprocity [1, 2]. Patches with elliptical shapes were used to investigate the effect of the azimuthal symmetry breaking on the local electrical field distributions for different cavity modes and on their excitation conditions. By using the actual patch radii plus the gap thickness as the effective radii, we show that the resonant condition based on Neumann boundary conditions show in excellent agreements with experimental and simulation results. This physical understanding of the resonant modes and their excitation conditions of the patch nanoantennas should be extendable to plasmonic patch nanoantennas with other geometrical shapes

Sample fabrication

Excitation of the cavity modes: experiments and simulations

Discussion

Conclusion