Engineering Topological States in Arrays of Two-mode Nanostructured Dielectric Waveguides

Designs of the optical structures that support topologically nontrivial states typically rely on the combining of simple single-mode meta-atoms in a lattice with a symmetry that guarantees the occurrence of the topological states. Here, we explore an alternative approach that does not require the us...

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Bibliographic Details
Main Authors: Mikhin, A. O., Rutckaia, V., Savelev, R. S., Sinev, I. S., Alu, A., Gorlach, M. A.
Format: Conference Proceeding
Language:English
Subjects:
Dielectrics
Electromagnetic waveguides
Frequency measurement
Lattices
Optical waveguide theory
Visualization
Waveguide lasers
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Summary:Designs of the optical structures that support topologically nontrivial states typically rely on the combining of simple single-mode meta-atoms in a lattice with a symmetry that guarantees the occurrence of the topological states. Here, we explore an alternative approach that does not require the use of complex lattice geometries, but instead relies on the tailoring of the spatial distribution of the near fields in the individual meta-atoms operating in the multi-mode regime. To this end we consider specially designed subwavelength grating dielectric waveguides with two quasi-degenerate modes that interfere in the near-field zone leading to highly asymmetric field patterns of the propagating waves. We show that a one-dimensional array of such waveguides exhibits non-trivial topological properties and supports topological edge states even with one waveguide in the unit cell. Theoretical predictions are confirmed experimentally by visualizing the excited states of the array by measuring the intensity of the radiation at the frequency of the third harmonic.
ISSN:2831-5804
DOI:10.1109/PIERS62282.2024.10618456