Probing the Band Structure of Topological Silicon Photonic Lattices in the Visible Spectrum

Peng, Siying; Schilder, Nick; Ni, Xiang; Groep, Jorik van de; Brongersma, Mark L.; Alù, Andrea; Khanikaev, Alexander B.; Atwater, Harry A.; Polman, A.

doi:10.1103/physrevlett.122.117401

Cited by 119 publications

(88 citation statements)

References 29 publications

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“…Here radiative effects would be more prominent but the topological properties would be qualitatively the same as we describe in this paper for smaller particles [46]. Experimental techniques such as cathodoluminescence spectroscopy and non-linear light generation can be used to probe topological band structures in photonics [54,65]. Plasmonic system with similar SSH-like physics have also been studied experimentally [66,67].…”

Section: Bec Breakdown In the Plasmonic Chainmentioning

confidence: 93%

Bulk-edge correspondence and long-range hopping in the topological plasmonic chain

2019

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The existence of topologically protected edge modes is often cited as a highly desirable trait of topological insulators. However, these edge states are not always present. A realistic physical treatment of long range hopping in a one-dimensional dipolar system can break the symmetry that protects the edge modes without affecting the bulk topological number, leading to a breakdown in bulk-edge correspondence. It is important to find a better understanding of where and how this occurs, as well as how to measure it. Here we examine the behaviour of the bulk and edge modes in a dimerised chain of metallic nanoparticles and in a simpler non-Hermitian next-nearest-neighbour model to provide some insight into the phenomena of bulk-edge breakdown. We construct bulk-edge correspondence phase diagrams for the simpler case and use these ideas to devise a measure of symmetry-breaking for the plasmonic system based on its bulk properties. This provides a parameter regime for which bulk-edge correspondence is preserved in the topological plasmonic chain, as well as a framework for assessing this phenomenon in other systems. arXiv:1902.00467v2 [cond-mat.mes-hall]

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Section: Bec Breakdown In the Plasmonic Chainmentioning

confidence: 93%

Bulk-edge correspondence and long-range hopping in the topological plasmonic chain

2019

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“…infrared CL measurements have probed the modal field distributions of TE and TM polarized modes in Si photonic crystal waveguides, 88 and most recently, topological Si photonic crystals. 89 In a related context, EELS was used to detect photonic Bloch modes in porous Al2O3 membranes 90 and Si photonic structures. 91…”

Section: Exciting Resonant Dielectric Nanostructuresmentioning

confidence: 99%

Electron-beam spectroscopy for nanophotonics

2019

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Progress in electron-beam spectroscopies has recently enabled the study of optical excitations with combined space, energy and time resolution in the nanometer, millielectronvolt and femtosecond domain, thus providing unique access into nanophotonic structures and their detailed optical responses. These techniques rely on ∼1-300 keV electron beams focused at the sample down to subnanometer spots, temporally compressed in wavepackets a few femtoseconds long, and in some cases controlled by ultrafast light pulses. The electrons undergo energy losses and gains, also giving rise to cathodoluminescence light emission, which are recorded to reveal the optical landscape along the beam path. This review portraits these advances, with a focus on coherent excitations, emphasizing the increasing level of control over the electron wave functions and ensuing applications in the study and technological use of optically resonant modes and polaritons in nanoparticles, 2D materials and engineered nanostructures.

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“…Most implementations so far have been limited to indirect probing of topological states such as transmission spectra [11,[18][19][20], which cannot provide spatially-resolved information about the edge modes and suffer from input/output coupling losses. Other recentlydemonstrated linear approaches such as near-field imaging [21], cathodoluminescence [22], and far-field imaging [23] suffer from poor spatial resolution or small field of view, leaving the edge states almost completely hidden in the background noise. Direct high-contrast imaging of the edge states is essential for assessing the fidelity of the topological waveguides, identifying potential sources of backscattering, and for optimizing the coupling between the edge states and localized emitters [5].Here we show that nonlinear topological photonics provides an effective way to overcome these limitations by observing nonlinear light conversion in a topological photonic nanostructure.…”

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confidence: 99%

Third-Harmonic Generation in Photonic Topological Metasurfaces

et al. 2019

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We study nonlinear effects in two-dimensional photonic metasurfaces supporting topologicallyprotected helical edge states at the nanoscale. We observe strong third-harmonic generation mediated by optical nonlinearities boosted by multipolar Mie resonances of silicon nanoparticles. Variation of the pump-beam wavelength enables independent high-contrast imaging of either bulk modes or spin-momentum-locked edge states. We demonstrate topology-driven tunable localization of the generated harmonic fields and map the pseudospin-dependent unidirectional waveguiding of the edge states bypassing sharp corners. Our observations establish dielectric metasurfaces as a promising platform for the robust generation and transport of photons in topological photonic nanostructures.Topological photonics describes optical structures with the properties analogous to electronic topological insulators [1]. These systems are distinguished by bulk band gaps that host disorder-robust states localized at edges or interfaces and provide a novel approach for designing non-reciprocal or localized modes for optical isolators, photonic-crystal waveguides, and lasers. Since the original demonstration of backscattering-immune photonic topological edge states with the use of a gyrotropic microwave photonic crystal under a strong magnetic field [2], there has been a concerted effort towards realizing topological photonics at the nanoscale. Recently suggested optical designs compatible with non-magnetic alldielectric structures [3][4][5][6][7][8] are now emerging as a promising platform for quantum and nonlinear topological photonics [9][10][11][12].Stimulated by the progress in nanofabrication techniques, a new favourable ground for topological photonics based on dielectric nanoparticles with high refractive index has recently emerged [13,14]. Strong optical resonances and low Ohmic losses make it feasible for practical implementation of topological order for light at subwavelength scales. The underlying conceptual framework is to use arrays of meta-atoms with judiciously engineered shape and lattice structure, with topologically nontrivial features arising from pseudospin degrees of freedom. It bridges fundamental physics of topological phases with resonant nanophotonics and multipolar electrodynamics [15,16]. Topological metasurfaces could form a ground for a new class of ultra-thin devices with functionalities based on novel physical principles through engineering light-matter interactions in synthetic photonic potentials [17]. Their pseudospindependent physics may be useful for manipulation of internal degrees of freedom of light such as polarization and angular momentum.However, the experimental characterization of topological photonic structures becomes much more challenging at the nanoscale. Most implementations so far have been limited to indirect probing of topological states such as transmission spectra [11,[18][19][20], which cannot provide spatially-resolved information about the edge modes and suffer from input/output coupling losses. ...

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Probing the Band Structure of Topological Silicon Photonic Lattices in the Visible Spectrum

Cited by 119 publications

References 29 publications

Bulk-edge correspondence and long-range hopping in the topological plasmonic chain

Bulk-edge correspondence and long-range hopping in the topological plasmonic chain

Electron-beam spectroscopy for nanophotonics

Third-Harmonic Generation in Photonic Topological Metasurfaces

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