Subwavelength localization and toroidal dipole moment of spoof surface plasmon polaritons

Kim, Seong Han; Oh, Suhk Kun; Kim, Kap-Joong; Kim, Jae‐Eun; Park, Hae Yong; Hess, Ortwin; Kee, Chul‐Sik

doi:10.1103/physrevb.91.035116

Cited by 80 publications

(31 citation statements)

References 64 publications

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“…3(a). Here, even though the surface waves are guided by metallic pillars similarly to the case of spoof surface plasmons supported by a square array of metallic pillars 25,29,31 , the dispersion relation is very different from that of conventional spoof surface plasmons, which starts at the light line and tends to zero group velocity at the band edge. Indeed, when excited, the cavity modes of each surface defect are tightly confined at the defect site and only a small portion of the field penetrates in the form of evanescent waves to reach the nearest neighbor.…”

Section: (B)mentioning

confidence: 96%

Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

Gao

Zhang

2016

Applied Physics Letters

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We experimentally demonstrate a type of waveguiding mechanism for coupled surfacewave defect modes in a surface-wave photonic crystal. Unlike conventional spoof surface plasmon waveguides, waveguiding of coupled surface-wave defect modes is achieved through weak coupling between tightly localized defect cavities in an otherwise gapped surface-wave photonic crystal, as a classical wave analogue of tightbinding electronic wavefunctions in solid state lattices. Wave patterns associated with the high transmission of coupled defect surface modes are directly mapped with a nearfield microwave scanning probe for various structures including a straight waveguide, a sharp corner and a T-shaped splitter. These results may find use in the design of integrated surface-wave devices with suppressed crosstalk.

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Section: (B)mentioning

confidence: 96%

Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

Gao

Zhang

2016

Applied Physics Letters

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“…3d) and disks 64,65 , while still supporting toroidal excitation modes. In the optical part of the spectrum, a toroidal dipole response, although weakened due to high ohmic losses in metals, was found in even simpler systems, such as plasmonic core-shell nanoparticles 66 , and bas-relief patterns that support spoof plasmons, including periodic grids 67 and arrays of ring-shaped grooves illuminated at oblique angles 68 (Fig. 3e).…”

Section: Toroidal Response In Artificial Mediamentioning

confidence: 99%

Electromagnetic toroidal excitations in matter and free space

et al. 2016

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The toroidal dipole is a localized electromagnetic excitation, distinct from the magnetic and electric dipoles. While the electric dipole can be understood as a pair of opposite charges and the magnetic dipole as a current loop, the toroidal dipole corresponds to currents flowing on the surface of a torus. Toroidal dipoles provide physically significant contributions to the basic characteristics of matter including absorption, dispersion, and optical activity. Toroidal excitations also exist in free-space as spatially and temporally localized electromagnetic pulses propagating at the speed of light and interacting with matter. We review recent experimental observations of resonant toroidal dipole excitations in metamaterials and the discovery of anapoles, non-radiating current configurations involving toroidal dipoles. While certain fundamental and practical aspects of toroidal electrodynamics remain open for the moment, we envision that exploitation of toroidal response can have important implications for the fields of photonics, sensing, energy and information. IntroductionThe interactions of electromagnetic radiation with matter underpin some of the most important technologies today -from telecommunications to information processing and data storage; from spectroscopy and imaging to light-assisted manufacturing. Our understanding and description of the electromagnetic properties of matter traditionally involves the concept of electric and magnetic dipoles, as well as their more complex combinations, known as multipoles. Introduced by Maxwell and Lorentz and later refined by Jackson and Landau, this framework, termed the multipole expansion, is central in physics and is being routinely applied in the study of optical, condensed matter, atomic, nuclear phenomena and beyond 1 . Within this framework, electromagnetic media can be represented by a set of point-like multipole sources [2][3][4][5] . The commonly used set of multipoles comprises the electric and magnetic families, which can be represented by oscillating charges and loop currents respectively. Dynamic toroidal multipoles constitute a third independent family of elementary electromagnetic sources, rather than an alternative multipole expansion or higher-order corrections to the conventional electric and magnetic multipoles (see tutorial inset I).Introduced in 1958 by Y. B. Zeldovich, toroidal moments have been considered in systems of toroidal topology (see Fig. 1) and studied in the context of nuclear 6 , atomic 7 , and molecular physics 8 , classical electrodynamics 9,10 , and solid state physics 3 . In the field of electromagnetism, in particular, a number of works have led to the development of a complete theoretical framework for toroidal electrodynamics [11][12][13][14][15] and the prediction of exotic effects, including dynamic non-radiating charge current configurations 10 and non-reciprocal interactions 9 . Following recent experimental observations of toroidal contributions in the response of materials across the electromagnetic spectrum, dyn...

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“…Despite these results were available for some time in the literature, it took more than thirty years to demonstrate experimentally the existence of these exotic states, first at microwave frequencies [13] and later, in a single-particle geometry, at optical frequencies [14,15], followed by an extensive theoretical work generalizing these findings to different materials and settings [16][17][18][19], also opening a direct link to optical invisibility [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Nonradiating photonics with resonant dielectric nanostructures

et al. 2019

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Nonradiating sources of energy have traditionally been studied in quantum mechanics and astrophysics, while receiving a very little attention in the photonics community. This situation has changed recently due to a number of pioneering theoretical studies and remarkable experimental demonstrations of the exotic states of light in dielectric resonant photonic structures and metasurfaces, with the possibility to localize efficiently the electromagnetic fields of high intensities within small volumes of matter. These recent advances underpin novel concepts in nanophotonics, and provide a promising pathway to overcome the problem of losses usually associated with metals and plasmonic materials for the efficient control of the light-matter interaction at the nanoscale. This review paper provides the general background and several snapshots of the recent results in this young yet prominent research field, focusing on two types of nonradiating states of light that both have been recently at the center of many studies in all-dielectric resonant meta-optics and metasurfaces: optical anapoles and photonic bound states in the continuum. We discuss a brief history of these states in optics, their underlying physics and manifestations, and also emphasize their differences and similarities. We also review some applications of such novel photonic states in both linear and nonlinear optics for the nanoscale field enhancement, a design of novel dielectric structures with high-resonances, nonlinear wave mixing and enhanced harmonic generation, as well as advanced concepts for lasing and optical neural networks. arXiv:1903.04756v1 [physics.optics]

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Subwavelength localization and toroidal dipole moment of spoof surface plasmon polaritons

Cited by 80 publications

References 64 publications

Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

Electromagnetic toroidal excitations in matter and free space

Nonradiating photonics with resonant dielectric nanostructures

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