Manipulation of pseudo-spin guiding and flat bands for topological edge states

Jiang, Zhen; Gao, Yongfeng; He, Liu; Sun, Jian; Song, Haitao; Wang, Quan

doi:10.1039/c9cp00789j

Cited by 22 publications

(8 citation statements)

References 32 publications

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“…Furthermore, the edge state becomes a flat band with near-zero group velocities in the vicinity of 0.612(2πc/a) for points A 0 and B 0 and 0.599(2πc/a) for points C 0 and D 0 (0.611(2πc/a) for points E 0 and F 0 and 0.593(2πc/a) for points G 0 and H 0 ), as shown in the rectangles presented in Figure 7a (Figure 7b), indicating that the slow-light waveguide can be successfully implemented by varying the shape of the scatterers rather than varying their arrangement. [41] Undeniably, this method is an excellent starting point for further realizing the slow-light effect in PC waveguides.…”

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confidence: 99%

Variation of Topological Edge States of 2D Honeycomb Lattice Photonic Crystals

Peng

Yan

Xie

et al. 2020

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Herein, the photonic quantum spin Hall effect is realized in a dielectric 2D honeycomb lattice photonic crystal (PC) with scatterers having various shapes, by stretching and shrinking the honeycomb unit cell. The topological edge states and their unidirectional transmission as scatterers with triangular, pentagonal, and heptagonal shapes are studied. The unidirectional transmission in an inverted Ω‐shaped waveguide, when different types of defects are incorporated, is realized to verify the characteristics of the topological protection. Moreover, flat band can be realized by varying the shape of several scatterers near the combined junction of PCs with different topological states, and the variation trend of flat band is evaluated with the increase in the edge number of varied scatterers from four to seven at different times. Moreover, a slow‐light waveguide is designed to further demonstrate the influence of the shape of scatterers on topological edge states for light transmission. Furthermore, the novel optical phenomenon of static state is realized; that is, light is not able to transmit but is trapped at the original position. This can increase the adjustability of the topological edge states and provide more potential applications for integrated photonic devices.

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confidence: 99%

Variation of Topological Edge States of 2D Honeycomb Lattice Photonic Crystals

Peng

Yan

Xie

et al. 2020

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“…As a result, the edge states have a reduction in backscattering over trivial ones (8,9). The method has since been applied to a variety of bosonic systems (10)(11)(12)(13)(14), and has recently experimentally been demonstrated in the visible regime (15).…”

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confidence: 99%

“…Effects reminiscent of the QSH phase such as a band inversion between dipolar and quadrupolar modes and pseudospin-dependent edge states are realized, but, rather than relying on the time reversal symmetric pairs characteristic of electronic systems, they instead rely on the spatial symmetry of the lattice structure. As a result, the edge states have a reduction in backscattering over trivial ones. , The method has since been applied to a variety of bosonic systems − and has recently experimentally been demonstrated in the visible regime …”

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confidence: 99%

Exciting Pseudospin-Dependent Edge States in Plasmonic Metasurfaces

et al. 2019

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We study a plasmonic metasurface that supports pseudospin dependent edge states confined at a subwavelength scale, considering full electrodynamic interactions including retardation and radiative effects. The spatial symmetry of the lattice of plasmonic nanoparticles gives rise to edge states with properties reminiscent of the quantum spin Hall effect in topological insulators. However, unlike the spin-momentum locking characteristic of topological insulators, these modes are not purely unidirectional and their propagation properties can be understood by analysing the spin angular momentum of the electromagnetic field, which is inhomogenous in the plane of the lattice. The local 1 sign of the spin angular momentum determines the propagation direction of the mode under a near-field excitation source. We also study the optical response under far-field excitation and discuss in detail the effects of radiation and retardation. dospin Topological insulators are materials which are insulating in the bulk but which have conduction surface states protected against disorder (1). The remarkable properties of these states in electronic systems has inspired the search for photonic topological insulators (PTIs), which aim to guide and manipulate photons with the same level of control and efficiency (2-6). Systems which possess these effects whilst preserving time reversal symmetry are appealing as they do not require complicated experimental setups such as strong magnetic fields or bianisotropic coupling. Motivated by this, a proposal to emulate the quantum spin Hall (QSH) effect in photonic crystals was presented by Wu and Hu in Ref. 7. Effects reminiscent of the QSH phase such as a band inversion between dipolar and quadrupolarmodes, and pseudospin dependent edge states are realised but, rather than relying on the time reversal symmetric pairs characteristic of electronic systems, they instead rely on the spatial symmetry of the lattice structure. As a result, the edge states have a reduction in backscattering over trivial ones (8,9). The method has since been applied to a variety of bosonic systems (10-14), and has recently experimentally been demonstrated in the visible regime (15).The combination of topological effects with plasmonics offers the possibility of precisely controlling light on the the nanoscale. The strong enhancement and localisation of electric fields due to localised surface plasmon (LSP) resonances (16) is a widely employed platform for light confinement on the nanoscale (17,18). Plasmonic metasurfaces can be formed by arranging plasmonic nanoparticles in two-dimensional (2D) lattices, where the LSPs become

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“…As a kind of periodic nanostructure, photonic crystals (PhCs) play an important role in both fundamental science [1][2][3][4] and optical/optoelectronic devices. 5,6 For example, self-assembled plasmonic PhCs provide a promising platform to develop nextgeneration optical/optoelectronic devices.…”

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confidence: 99%