Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 40: Poster – Photonics

Q 40.13: Poster

Mittwoch, 4. März 2026, 17:00–19:00, Philo 1. OG

The SSH model in non-dimerized chains via multimode waveguides — •Ian Heil, Julian Schulz, and Christina Jörg — Physics Department and Research Center OPTIMAS, RPTU Kaiserslautern-Landau

Topological photonic waveguide arrays based on the Su-Schrieffer-Heeger (SSH) model typically rely on an alternating spacing between neighboring waveguides. Therefore, the distinction between the trivial and topological phases is sensitive to the geometric layout and the presence or absence of individual sites. In this work, we introduce a fundamentally different strategy. We investigate a non-dimerized chain of multimode waveguides whose elliptical geometry enables control over the coupling between s-, p-, and d-like modes [1]. Here, the topology arises because two distinct transverse modes form an effective two-site basis within each real-space waveguide, yielding a synthetic dimerization even though the physical lattice contains only a single site per unit cell. This effective model reproduces SSH-like physics without requiring any spatial alternation of waveguide positions. Because the topological phase is encoded in the modal degrees of freedom rather than real-space geometry, edge states persist regardless of the number of waveguides, and adding or removing sites at the boundaries does not affect the topological character. Through changes in ellipticity or spacing between waveguides, we demonstrate controllable transitions between trivial and topological phases. This mode-based strategy offers a route to reconfigurable topological photonic systems.

[1] G. Liu et al. PRB 110, 214110 (2024)

Keywords: SSH model; topology; higher modes; waveguides; structured light