Understanding the Physical Behavior of Plasmonic Antennas Through Computational Electromagnetics

Abstract

This chapter focuses on understanding the electromagnetic response of nanoscopic metallic antennas through a classical computational electromagnetic algorithm: volumetric method of moments (V-MoMs). Under the assumption that metals only respond to external electromagnetic disturbance locally, we rigorously formulate the light-nanoantenna interaction in terms of a volume integral equation (VIE) and solve the equation by using the method of moments algorithm. Modes of a nanoantenna, as the excitation independent solution to the volume integral equation (VIE), are introduced to resolve the antenna's complex optical spectrum. Group representation theory is then employed to reveal how the symmetry of a nanoantenna defines the modes' properties and determines the antenna's optical response. Through such a treatment, a set of tools that can systematically treat the interaction of light with a nanoantenna is developed, paving the road for future nanoantenna design.

Detection of 2,4-Dinitrotoluene by Metal-Graphene Hybrid Plasmonic Nanoantennas with a Golden Ratio Rectangular Resonator

“…Based on this figure, the rectangular Au structure designed with the golden ratio exhibits remarkable absorption of 95 % at the resonance wavelength (5887 nm). The physical origin of this resonance behaviour of the nanoscopic metallic antenna has been analytically studied by Zheng, Vandenbosch, and Moshchalkov [24]. Figure 1(c) shows that the strong and stable resonance mode can be obtained successfully by implementing golden ratios on the side lengths of the resonator without the need to satisfy the equivalent impedance, which is a timely and costly optimisation process.…”

A Boundary Integral Equation Scheme for Simulating the Nonlocal Hydrodynamic Response of Metallic Antennas at Deep-Nanometer Scales

“…In order to connect the vector potentials and the scalar potentials in different regions, a set of interface conditions must be established based on Maxwell's equations in (4) (see the proofs in the Appendix). Since both the internal and external media are assumed to be nonmagnetic, the magnetic field is continuous across the boundary.…”

“…Consequently, the current flowing in the antenna must be modeled as a volume current [3]. Hence, the modeling of a plasmonic nanoantenna is not fundamentally different from the modeling of a dielectric antenna [4], [5].…”