Theoretical seminar. Roman Saveliev
Lomonosova 9, room 1220
‘Topological states in arrays of periodic dielectric waveguides engineered via mode interference’
Abstract: Photonic structures with topologically nontrivial bands are usually designed by arranging simple meta-atoms, ideally, single-mode ones, in a carefully designed photonic lattice with symmetry that guarantees the emergence of topological states. Here, we investigate an alternative option which does not require complex lattice geometry but instead relies on tuning of the parameters of the individual sites to achieve the degeneracy of the modes with different symmetry. Namely, we consider a one-dimensional array of equidistant identical periodic waveguides supporting degenerate modes with strongly asymmetric near field profiles giving rise to the coupling modulation. Exploiting this feature, we demonstrate that the proposed system supports topological edge modes and can be viewed as a generalization of the paradigmatic Su-Schrieffer-Heeger model, reducing to it for the suitable parameter choice. We also discuss a feasible experimental procedure that allows for excitation and detection of the predicted edge states in the far-field based by choosing the appropriate polarization of the excited beam.
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