Robust multimode interference and conversion in topological unidirectional surface magnetoplasmons

TL;DR

This paper theoretically demonstrates topological unidirectional surface magnetoplasmons in a YIG waveguide, enabling robust multimode interference, mode conversion, and tunable splitters with potential for manipulating topological waves.

Contribution

It introduces a novel topological waveguide supporting unidirectional SMPs and demonstrates magnetically controllable multimode interference and mode conversion based on these topological modes.

Findings

Support for topological unidirectional SMPs in YIG waveguides

Robust multimode interference and mode conversion achieved

Tunable splitters based on unidirectional SMPs

Abstract

We have theoretically investigated surface magnetoplasmons (SMPs) in a yttrium-iron-garnet (YIG) sandwiched waveguide. The dispersion demonstated that this waveguide can support topological unidirectional SMPs. Based on unidirectional SMPs, magnetically controllable multimode interference (MMI) is verified in both symmetric and asymmetric waveguides. Due to the coupling between the modes along two YIG-air interfaces, the asymmetric waveguide supports a unidirectional even mode within a single-mode frequency range. Moreover, these modes are topological protected when disorder is introduced. Utilizing robust unidirectional SMPs MMI (USMMI), tunable splitters have been achieved. It has been demonstrated that mode conversion between different modes can be realized. These results provide many degrees of freedom to manipulate topological waves.