Illuminating Dark Plasmons of Silver Nanoantenna Rings to Enhance Exciton–Plasmon Interactions

Abstract

The chemical growth of silver nanorings that possess singly twinned crystals and a circular cross section via a reductive reaction solution is reported. The wire and ring diameters of the synthesized nanorings are in the ranges 80–200 nm and 4.5–18.0 μm, respectively. By lighting up the multipolar dark plasmons with slanted illumination, the silver nanoring exhibits unique focused scattering and large local‐field enhancement. We also demonstrate strong exciton–plasmon interactions between a monolayer of CdSe/ZnS semiconductor quantum dots and a single silver antenna‐like nanoring (nanoantenna) at the “hot spots” located at the cross points of the incident plane and nanoring; the position of these spots are tunable by adjusting the incidence angle of illumination. The tunable plasmonic behavior of the silver nanorings could find applications as optical nanoantennae or plasmonic nanocavities.

Plasmon mode excitation and photoluminescence enhancement on silver nanoring

“…It should be noted that this result is in good qualitatively and quantitatively agreement with the results obtained for nanorings with significantly larger radii (up to 10 μm, [22,26]), demonstrating the universal character of the oblique laser radiation scattering on such nanostructures. Note that similar scattering patterns are observed under oblique irradiation of the nanoring using different wavelengths (not shown in this paper) demonstrating that the fabricated nanorings despite some geometric shape imperfections exhibit optical properties similar to the properties of both nanorings fabricated by e-beam lithography and chemically synthesized single-crystalline Ag nanorings with almost perfect geometric shape [5,22,23,26].…”

“…The metal nanoring with the outer radius R ring significantly greater than the ring thickness t (R ring c t) represents an antennalike nanostructure amplifying incident electromagnetic radiation via the strong coupling to the circumferentially traveling surface plasmon modes [5,22]. Such nanostructure also can be used to efficiently convert the incoming propagating radiation into the strong evanescent waves [23].…”

“…Such nanostructures have already found their way into many areas: surface enhanced spectroscopy (SERS, SEIRA) as highly effective antennas [5], optical data storage as recording marks to achieve super resolution [6], the optical telecommunications band as plasmonic waveguides [7] as well as in biological and chemical sensors [8]. To produce ring metal nanostructures, methods of colloidal [2], electron [3], and ion beam lithography [5] as well as chemical synthesis [4] are applied, which enables us to create single nanorings of various size, geometry, and form, as well as their periodic arrays. However, technologically much simpler laser surface modification techniques can be found having proved the ability to create a wide range of functional nanostructures [9][10][11][12][13][14][15][16][17].…”

Scattering of a Single Plasmon by Two-Level and V-Type Three-Level Quantum Dot Systems Coupled to 1D Waveguide

“…In this limit, the effective Purcell factor P≡Г pl /Г′ can exceed 10 3 in realistic systems according to the theoretical results [26], where Г pl is the spontaneous emission rate into the surface plasmons (photons) and Г′ describes contributions from both emission into free space and non-radiative emission via ohmic losses in the conductor. Both experimental and theoretical investigations show that the emission properties of QDs can be significantly modified near the metallic nanostructures [27,28]. Recent investigations have further extended into the regime of interactions of quantum emitters such as QDs and propagating surface plasmons (SPs) [29].…”

Ultrahigh Density Arrays of Toroidal ZnO Nanostructures by One‐Step Cooperative Self‐Assembly Processes: Mechanism of Structural Evolution and Hybridization with Au Nanoparticles

“…[1][2][3] Ring-shaped or donut-like toroidal nanostructures are examples of extraordinary systems that have attracted increasing interest due to their unique properties. [4][5][6] Various materials such as gold, [6][7][8][9][10][11][12][13][14][15][16] silver, [17][18][19][20][21] cobalt, [22,23] nickel, [24,25] iron, [26] chromium, [27] carbon, [28] cadmium sulfide, [29] tin oxide, [30] silica, [31] InGaN, [32] titania, [33] and zinc oxide (ZnO) [34] have been fabricated by template methods, [9-13, 19-26, 31-33] lithography or etching, [6,16,35,36] polyol methods, [17,18] molecular beam epitaxy, [15,34,[37][38][39] and self-assembly processes. [29,…”