Experimental demonstration of linear and spinning Janus dipoles for polarisation- and wavelength-selective near-field coupling

Picardi, Michela F.; Neugebauer, Martin; Eismann, Jörg S.; Leuchs, Gerd; Banzer, Peter; Rodríguez-Fortuño, Francisco J.; Zayats, Anatoly V.

doi:10.1038/s41377-019-0162-x

Cited by 52 publications

(31 citation statements)

References 32 publications

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“…Further degrees of freedom for engineering unidirectionality would be offered by using polarization degrees of freedom. While we have considered only radially polarizable electric dipole antennas in this work, in fact, high-index dielectric particles and metallic split-ring shapes can show electric, magnetic, and coupled magneto-electric dipole polarizabilities, as reported in recent works on Janus, Kerker, and Huygens scatterers 42,43 . The excitation of suitable linear combinations of these moments is intrinsically associated with directional scattering.…”

Section: Discussionmentioning

confidence: 91%

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources

et al. 2019

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We analyse the resonant mode structure and local density of states in high-Q hybrid plasmonic-photonic resonators composed of dielectric microdisks hybridized with pairs of plasmon antennas that are systematically swept in position through the cavity mode. On the one hand, this system is a classical realization of the cooperative resonant dipole–dipole interaction through a cavity mode, as is evident through predicted and measured resonance linewidths and shifts. At the same time, our work introduces the notion of ‘phased array’ antenna physics into plasmonic-photonic resonators. We predict that one may construct large local density of states (LDOS) enhancements exceeding those given by a single antenna, which are ‘chiral’ in the sense of correlating with the unidirectional injection of fluorescence into the cavity. We report an experiment probing the resonances of silicon nitride microdisks decorated with aluminium antenna dimers. Measurements directly confirm the predicted cooperative effects of the coupled dipole antennas as a function of the antenna spacing on the hybrid mode quality factors and resonance conditions.

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Section: Discussionmentioning

confidence: 91%

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources

et al. 2019

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“…Anomalous unidirectional excitation by an all-electric Huygens metasource in HMMs provides new ways to control EM waves within a near-field regime. Recently, special near-field dipoles, including spin dipoles, 64,65 Huygens dipoles, 66,67 Janus dipoles, 48 and composite spinning dipoles, 68,69 have provided a good platform for studying interesting physical mechanisms such as transverse-spin-associated globally unique handedness, 70 bulk EM waves, 35,71 bound states in continuum, 72 and topological edge states. 73,74 In this section, we demonstrate experimentally that a spin metasource can be used to produce the anomalous PSHE in a hyperbolic waveguide.…”

Section: Unidirectional Excitations Of Hyperbolic Guided Modes Using a Spin Metasourcementioning

confidence: 99%

Anomalous unidirectional excitation of high-k hyperbolic modes using all-electric metasources

et al. 2021

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The unidirectional excitation of near-field optical modes is a fundamental prerequisite for many photonic applications, such as wireless power transfer and information communications. We experimentally construct all-electric Huygens and spin metasources and demonstrate anomalous unidirectional excitation of high-k hyperbolic modes in two types of hyperbolic metasurfaces. We use a Huygens metasource to study the unidirectional excitation of hyperbolic bulk modes in a planar hyperbolic metamaterial (HMM). Specifically, unidirectional excitation is the same as that in free space in the vertical direction, but opposite to that in free space in the horizontal direction. This anomalous unidirectional excitation is determined by the anisotropic HMM dispersion. In addition, we use a spin metasource to observe the anomalous photonic spin Hall effect in a planar hyperbolic waveguide. For a near-field source with a specific spin, the guide mode with a fixed directional wave vector is excited due to spin-momentum locking. Because the directions of momentum and energy flows in the HMM waveguide are opposite, the unidirectional excitation of hyperbolic guided modes is reversed. Our results not only uncover the sophisticated electromagnetic functionalities of metasources in the near-field but may also provide novel opportunities for the development of integrated optical devices.

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“…And some geometrical and dynamic properties about longitudinal waves are usually overlooked, for example the acoustic spin angular momentum, which was not considered until recently [ 25–27 ]. Therefore, despite many optical near-field research works [ 23 , 24 , 28 ], mapping the near-field research from electromagnetics to acoustics is not a transparent and trivial task.…”

Section: Introductionmentioning

confidence: 99%

Symmetry selective directionality in near-field acoustics

Long

Zhang

et al. 2020

National Science Review

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Understanding unidirectional and topological wave phenomena requires the unveiling of intrinsic geometry and symmetry for wave dynamics. This is essential yet challenging for the flexible control of near-field evanescent waves, highly desirable in broad practical scenarios ranging from information communication to energy radiation. However, exploitations of near-field waves are limited by a lack of fundamental understanding about inherent near-field symmetry and directional coupling at sub-wavelengths, especially for longitudinal waves. Here, based on the acoustic wave platform, we show the efficient selective couplings enabled by near-field symmetry properties. Based on the inherent symmetry properties of three geometrically orthogonal vectors in near-field acoustics, we successfully realize acoustic Janus, Huygens, spin sources and quadrupole hybrid sources, respectively. Moreover, we experimentally demonstrate fertile symmetry selective directionality of those evanescent modes, supported by two opposite meta-surfaces. The symmetry properties of the near-field acoustic spin angular momenta are revealed by directly measuring local vectorial fields. Our findings advance the understanding of symmetries in near-field physics, supply feasible approaches for directional couplings, and pave the way for promising acoustic devices in the future.

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Experimental demonstration of linear and spinning Janus dipoles for polarisation- and wavelength-selective near-field coupling

Cited by 52 publications

References 32 publications

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources

Anomalous unidirectional excitation of high-k hyperbolic modes using all-electric metasources

Symmetry selective directionality in near-field acoustics

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