Experimental observation of optical Weyl points and Fermi arc-like surface states

By Jiho Noh, Sheng Huang, D. Leykam, Y. Chong, Kevin P. Chen, M. Rechtsman. Nature Physics, 2016

271 citations recorded by the source corpus.

Weyl fermions are hypothetical two-component massless relativistic particles in three-dimensional (3D) space, proposed by Hermann Weyl in 1929. Their band-crossing points, called ‘Weyl points’, carry a topological charge and are therefore highly robust. There has been much excitement over recent observations of Weyl points in microwave photonic crystals and the semimetal TaAs. Here, we report on the experimental observation of ‘type-II’ Weyl points of light at optical frequencies, with the photons having a strictly positive group velocity along one spatial direction. We use a 3D structure consisting of laser-written waveguides, and show the presence of type-II Weyl points by observing conical diffraction along one axis when the frequency is tuned to the Weyl point; and observing the associated Fermi arc-like surface states. The realization of Weyl points at optical frequencies allows these novel electromagnetic modes to be further explored in the context of linear, nonlinear, and quantum optics. Three-dimensional laser-written waveguide arrays are used to demonstrate type-II Weyl points, along with Fermi arc-like surface states, for light at optical wavelengths.

Subfields: Atomic and Molecular Physics, and Optics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/51521d7bcaaf92e12bc266e14eb8eecd6a9e6c89

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. A. Amo
2. Ashvin Vishwanath
3. N. P. Armitage
4. Ling Lu
5. M. Rechtsman
6. Zhong Wang
7. E. Mele
8. Jacqueline Bloch

In Statistical and Nonlinear Physics

1. A. Amo
2. Ling Lu
3. Ashvin Vishwanath
4. Zhong Wang
5. Zhongbo Yan
6. M. Rechtsman
7. S. Longhi

Citations in the corpus

• Experimental discovery of nodal chains (2017, background): “[34] Jiho Noh, Sheng Huang, Daniel Leykam, YD Chong, Kevin P Chen, and Mikael C Rechtsman, “Experimental observation of optical weyl points and fermi arc-like surface states,” Nature Physics (2017).”
• Experimental realization of a Weyl exceptional ring (2018, background): “In the Hermitian limit, τ = 0, this helical waveguide array possesses a type-II Weyl point, whose dispersion is strongly anisotropic because both bands represent modes traveling in the same direction along the z axis [31].”
• Roadmap on topological photonics (2022, unknown): “Optical Weyl points based on such an approach have been experimentally demonstrated [69].”
• Topological Photonic Crystals: Physics, Designs, and Applications (2022, background): “Up to now, topological phenomena have been proposed and realized in diverse photonic systems, including photonic crystals (PCs) [16-25], plasmonic systems [18-29], metamaterials [30-42], coupled resonator optical waveguides [43-53], waveguide arrays [54-66], microcavity polaritonic systems [67-74], ”
• Type-III and Tilted Dirac Cones Emerging from Flat Bands in Photonic Orbital Graphene (2018, methodology): “Using more sophisticated approaches, evidence of type-II Weyl points has recently been reported in microwave metamaterials [33,34] and via conical diffraction in laser-written waveguides with elaborate couplings [35].”
• Weyl and Dirac semimetals in three-dimensional solids (2017, methodology): “Using a 3D structure consisting of laser-written waveguides, Noh et al., 2017 have observed photonic type-II Weyl points at optical frequencies, in a 3D photonic crystal structure consisting of evanescently-coupled waveguides.”