Multipolar radiation of quantum emitters with nanowire optical antennas

Abstract

Multipolar transitions other than electric dipoles are generally too weak to be observed at optical frequencies in single quantum emitters. For example, fluorescent molecules and quantum dots have dimensions much smaller than the wavelength of light and therefore emit predominantly as electric dipoles. Here we demonstrate controlled emission of a quantum dot into multipolar radiation through selective coupling to a linear nanowire antenna. The antenna resonance tailors the interaction of the quantum dot with light, effectively creating a hybrid nanoscale source beyond the simple Hertz dipole. Our findings establish a basis for the controlled driving of fundamental modes in nanoantennas and metamaterials, for the understanding of the coupling of quantum emitters to nanophotonic devices such as waveguides and nanolasers, and for the development of innovative quantum nano-optics components with properties not found in nature.

Identifying diamagnetic interactions in scattering and nonlinear optics

“…However, in a single dynamical system where the equations of motion of (6) both matter and radiation are dependent on one another, the coupling appears as the interaction term Lint. The explicit form of the multipolar Lagrangian is given by where the vector field, nα(ξ,r), is defined as…”

“…In consequence, higher-order couplings expressed in multipolar form, such as the light-matter interactions mediated by a magnetic dipole, can usually be disregarded. However, these higher-order terms are important for certain systems, such as chiral discrimination in molecules of low symmetry [1,2], light-harvesting complexes [3], nanomaterials [4][5][6], metamaterials [7,8] and numerous theoretical studies including optical trapping [9][10][11][12][13][14]. Such terms also assume greater significance for systems in which electric-dipole couplings are either very small or vanish altogether-when, for example, a relevant electronic transition is electric-dipole forbidden by symmetry.…”

Giant Suppression of Photobleaching for Single Molecule Detection via the Purcell Effect

“…These include monopole, 21 dipole, 36 bowtie, 33 diabolo, 37 and dimer 38,39 antennas. The strong Purcell effect of the plasmonic nanoantennas have been shown to redirect emission direction from a single emitter 24,35 and enhance spontaneous emission rate by 2 orders of magnitude. 23 Here, we use a single-molecule approach to examine the suppression of photobleaching by the Purcell effect via plasmonic nanostructures and demonstrate that the strong Purcell effect of a dimer antenna can effectively steer a fluorophore away from photobleaching and significantly prolong the fluorophore's lifespan.…”

Directional emission from a single plasmonic scatterer

“…For larger sizes higher-order multipole contributions become significant. The coupling efficiency to different moments strongly depends on the type of excitation 43,44 , particle shape and dielectric environment. In particular for cases where the particles have a non-spherical shape and/or are placed in an asymmetric dielectric environment like on a substrate, quantifying the contributions of the different multipoles is complex.…”

“…Next, using the theoretical far fields of the relevant multipole components we decompose the experimental far-field angular radiation patterns by numerically fitting the complex amplitudes using a least-squares numerical optimization routine 44,52 . For the smaller disks (D ¼ 50-100 nm) the patterns are dominated by p x and p z due to their size compared with the wavelength, so using only those components for the data-fitting yields good results (see Fig.…”