Plasmonic nanoarcs: a versatile platform with tunable localized surface plasmon resonances in octave intervals.

Kunyi Zhang,Oded Rabin,Andrew P Lawson,Thomas E Murphy,Chase T Ellis,Hans A Bechtel,Matthew S Davis,Joseph G Tischler

doi:10.1364/oe.403728

Abstract

The tunability of the longitudinal localized surface plasmon resonances (LSPRs) of metallic nanoarcs is demonstrated with key relationships identified between geometric parameters of the arcs and their resonances in the infrared. The wavelength of the LSPRs is tuned by the mid-arc length of the nanoarc. The ratio between the attenuation of the fundamental and second order LSPRs is governed by the nanoarc central angle. Beneficial for plasmonic enhancement of harmonic generation, these two resonances can be tuned independently to obtain octave intervals through the design of a non-uniform arc-width profile. Because the character of the fundamental LSPR mode in nanoarcs combines an electric and a magnetic dipole, plasmonic nanoarcs with tunable resonances can serve as versatile building blocks for chiroptical and nonlinear optical devices.

Highlights

Plasmonic nanoantennas possess fascinating optical properties with a wide range of applications in molecular spectroscopy [1,2,3] and photonics technologies. [4, 5] The novel optical properties arise from the interaction between light and surface plasmons
The two types of nanostructures share the same Localized surface plasmon resonances (LSPRs) wavelengths and the well-studied plasmonic characteristics of nanorods can be directly applied to predict the behavior of nanoarcs
With the experimental and numerical simulation results, we have shown that Lmid is an effective length that determines the LSPR wavelengths of nanoarcs with uniform width

Summary

Introduction

Plasmonic nanoantennas possess fascinating optical properties with a wide range of applications in molecular spectroscopy [1,2,3] and photonics technologies. [4, 5] The novel optical properties arise from the interaction between light and surface plasmons. Localized surface plasmon resonances (LSPRs) of plasmonic nanoantennas can be excited by light with proper frequency and polarization, resulting in strongly enhanced local electromagnetic field. The frequencies of these resonances depend strongly on the plasmonic object shape, size, and material as well as the dielectric environment [2, 3]. Plasmonic nanorods (Fig. 1(a)) are uniaxial nanostructures that act as microscopic antennae inasmuch as they absorb, scatter and emit electromagnetic radiation of a particular polarization at characteristic frequencies that correspond to the dipolar LSPR modes. The longitudinal LSPRs in plasmonic nanorods are highly tunable (across the visible and infrared spectra, for Au and Ag nanorods) by adjusting the nanorod length, while the transverse LSPRs typically resonate at significantly higher frequencies and their tunability is negligible for high aspect ratio nanostructures. [32, 37] Due to symmetry, the even-order LSPR modes in nanorods are dark modes

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Conclusion