All-Si valley-Hall photonic topological insulator

Ma, Tzuhsuan; Shvets, Gennady

doi:10.1088/1367-2630/18/2/025012

Cited by 612 publications

(469 citation statements)

References 38 publications

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“…According to k·p method, the effective Hamiltonian around K/K′ valley can be expressed as H K/K′ ( δ k ) = ±( v D δk x σ x + v D δk y σ y ) ± mv D 2 σ z , where δ k = k − k K/K′ is the displacement of wave vector k to K/K′ valley in the reciprocal space, v D is the group velocity, m is the effective mass term, and σ i = ( i = x, y, z ) are elements in the Pauli matrices . Solving the effective Hamiltonian, we can obtain the Berry curvature at K/K′ valley,

Ω_{K / {normalK}^{'}} (δ k) = \pm \frac{m v_{normalD}}{2 {(δ k^{2} + m^{2} v_{normalD}^{2})}^{3 / 2}}

.…”

mentioning

confidence: 99%

Valley‐Hall Photonic Topological Insulators with Dual‐Band Kink States

Chen

Zhang

et al. 2019

Advanced Optical Materials

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Extensive researches have revealed that valley, a binary degree of freedom (DOF), can be an excellent candidate of information carrier. Recently, valley DOF is introduced into photonic systems, and several valley‐Hall photonic topological insulators (PTIs) are experimentally demonstrated. However, in the previous valley‐Hall PTIs, topological kink states only work at a single frequency band, which limits potential applications in multiband waveguides, filters, communications, and so on. To overcome this challenge, here a valley‐Hall PTI, where the topological kink states exist at two separated frequency bands, is experimentally demonstrated in a microwave substrate‐integrated circuitry. Both the simulated and experimental results demonstrate the dual‐band valley‐Hall topological kink states are robust against the sharp bends of the internal domain wall with negligible intervalley scattering. This work may pave the way for multichannel substrate‐integrated photonic devices with high efficiency and high capacity for information communications and processing.

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Ω_{K / {normalK}^{'}} (δ k) = \pm \frac{m v_{normalD}}{2 {(δ k^{2} + m^{2} v_{normalD}^{2})}^{3 / 2}}

.…”

mentioning

confidence: 99%

Valley‐Hall Photonic Topological Insulators with Dual‐Band Kink States

Chen

Zhang

et al. 2019

Advanced Optical Materials

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“…This map proves that the wave is indeed guided by the interface line between the two inverted dual‐metasurfaces with good localization and negligible scattering losses at the bends. Note that the edge modes are also robust against 90° bends, as demonstrated in Figure d, since they could also occur along the armchair edge of the hexagonal metasurface, unlike the so‐called valley topological insulators …”

Section: Resultsmentioning

confidence: 96%

Electromagnetic‐Dual Metasurfaces for Topological States along a 1D Interface

Bisharat

Sievenpiper

2019

Laser & Photonics Reviews

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The discovery of topological insulators was rapidly followed by the advent of their photonic analogues, motivated by the prospect of backscattering‐immune light propagation. So far, however, implementations have mainly relied on engineering bulk modes in photonic crystals and waveguide arrays in two‐dimensional (2D) systems, which closely mimic their electronic counterparts. In addition, metamaterials‐based implementations subject to electromagnetic duality and bianisotropy conditions suffer from intricate designs and narrow operating bandwidths. Here, it is shown that symmetry‐protected topological states akin to the quantum spin‐Hall effect can be realized in a straightforward manner by coupling surface modes over metasurfaces of complementary electromagnetic responses. Specifically, stacking unit cells of such metasurfaces directly results in double Dirac cones of degenerate transverse‐electric (TE) and transverse‐magnetic (TM) modes, which break into a wide nontrivial bandgap at small interlayer separation. Consequently, the ultrathin structure supports robust gapless edge states, which are confined along a one‐dimensional (1D) line rather than a surface interface, as demonstrated at microwave frequencies by near‐field imaging. The simplicity and versatility of the proposed approach proves attractive as a tabletop platform for the study of classical topological phases, as well as for applications benefiting the compactness of metasurfaces and the potential of topological insulators.

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“…It is based on the one described by Ma and Shvets in ref. []. Starting from a triangular array of dielectric cylinders made of silicon, ε = 13, and radius R = 0.3075 a 0 (upper panel of Figure 2a).…”

Section: Topological Photonic Systems: Examplesmentioning

confidence: 99%

Tutorial: Computing Topological Invariants in 2D Photonic Crystals

et al. 2019

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The field of topological photonics emerged as one of the most promising areas for applications in transformative technologies: possible applications are in topological lasers or quantum optics interfaces. Nevertheless, efficient and simple methods for diagnosing the topology of optical systems remain elusive for an important part of the community. Herein, a summary of numerical methods to calculate topological invariants emerging from the propagation of light in photonic crystals is provided. The fundamental properties of wave propagation in lattices with a space‐dependent periodic electric permittivity is first described. Next, an introduction to topological invariants is provided, proposing an optimal strategy to calculate them through the numerical evaluation of Maxwell's equation in a discretized reciprocal space. Finally, the tutorial is complemented with a few practical examples of photonic crystal systems showing different topological properties, such as photonic valley‐Chern insulators, photonic crystals presenting an “obstructed atomic limit”, photonic systems supporting fragile topology, and finally photonic Chern insulators, where the magnetic permeability is also periodically modulated.

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All-Si valley-Hall photonic topological insulator

Cited by 612 publications

References 38 publications

Valley‐Hall Photonic Topological Insulators with Dual‐Band Kink States

Valley‐Hall Photonic Topological Insulators with Dual‐Band Kink States

Electromagnetic‐Dual Metasurfaces for Topological States along a 1D Interface

Tutorial: Computing Topological Invariants in 2D Photonic Crystals

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