Symmetry‐Protected Spoof Localized Surface Plasmonic Skyrmion

Abstract

Electromagnetic (EM) skyrmions are an EM analogue of the skyrmions in condensed matter physics, offering new degrees of freedom to structure light and manipulate light–matter interactions and thus promising various groundbreaking applications in optics and photonics. Recently, there is a growing interest in composing EM skyrmions based on different field vectors of EM waves. Here, an EM skyrmion is realized, i.e., a spoof plasmonic skyrmion (SPS), using the electric field vectors of spoof localized surface plasmons (LSPs) in a planar microwave resonator with rotational and mirroring symmetries. The SPS is constructed by synthesizing a scalar vortex (a topological charge 0) and a polarization vortex (a topological charge 1) in the in‐plane and the out‐of‐plane component of the fields, respectively. Besides an experimental demonstration, group theory is employed and pinpoints the symmetry origin of the skyrmion. This investigation demonstrates the ubiquity of the existence of the skyrmion in any planar EM resonator holding rotational and mirroring symmetries, regardless the dimensions and the operating frequencies. This skyrmion design not only promises novel microwave applications for sensing and transferring information, but also lays down a general guideline for devising skyrmions operating over a broad range in the EM spectra.

Topological quasiparticles of light: Optical skyrmions and beyond

“…Dynamics of such skyrmionic SPP standing wave can be observed using photoemission electron microscopy [44]. Spoof localized SPP were also reported to generate skyrmion-like structures for the fields in a coiled metal films or metallic multifold structure acting as a resonator [45,46] but the topological protection needs to be further investigated. SPP field-skyrmions have the topological texture limited to Néel-type topology.…”

Near-field chiral excitation of universal spin-momentum locking transport of edge waves in microwave metamaterials

“…Spoof SPPs contain fruitful phenomena related to spin-orbit momentum. 20,21 It is convenient to use modulated gratings to couple CP spatial waves to unidirectional spoof SPPs on an open metasurface. 22 However, it is challenging to apply similar technology to one-dimensional infinitely thin spoof SPPs transmission lines 23,24 due to the small cross section.…”

Fractional‐Order Localized Spoof Surface Plasmons for In‐Phase or Out‐of‐Phase Power Division

“…202200645 Many components and devices based on the LSSPs with different functions have been developed, such as sensors, [19][20][21][22][23][24][25] bandpass filters, [26][27] invisibility cloaks, [28][29][30][31] antennas, [32][33][34] vortex-beam emitters, [35][36][37][38][39][40] planar waveguides, [41][42][43] isolators, [44] circulators, [45] directional couplers, [46] and skyrmion generators. [47] According to different classification criteria, they can be divided into one-port, two-port, and four-port components; active and passive devices; [48] reciprocal and nonreciprocal networks; etc. However, rat-race couplers based on the LSSPs have not been reported before, and predictably the rat-race couplers will be more compact with the adoption of the LSSPs.…”