Abstract
We experimentally demonstrate topological edge states arising from the valley-Hall effect in two-dimensional honeycomb photonic lattices with broken inversion symmetry. We break the inversion symmetry by detuning the refractive indices of the two honeycomb sublattices, giving rise to a boron nitridelike band structure. The edge states therefore exist along the domain walls between regions of opposite valley Chern numbers. We probe both the armchair and zigzag domain walls and show that the former become gapped for any detuning, whereas the latter remain ungapped until a cutoff is reached. The valley-Hall effect provides a new mechanism for the realization of time-reversal-invariant photonic topological insulators.
- Received 31 May 2017
DOI:https://doi.org/10.1103/PhysRevLett.120.063902
© 2018 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Having the Edge on Optical Losses
Published 6 February 2018
An optical version of a topological insulator exhibits edge states that could be used to reduce scattering losses in optical waveguides.
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