# Making the guided wave propagate unidirectional in periodic dielectric waveguide

## TL;DR

This paper demonstrates unidirectional guided wave modes in a periodic dielectric chain with gyromagnetic rods, breaking time-mirror symmetry, and confirms their properties experimentally, opening new possibilities for electromagnetic wave manipulation.

## Contribution

The study introduces a novel unidirectional waveguide mode in dielectric chains with gyromagnetic rods, controlled by rod arrangement, and demonstrates a vortex wave generator based on these modes.

## Key findings

- Unidirectional waveguide modes are achieved in dielectric chains.
- Wave directionality can be switched by changing rod arrangement.
- Experimental results confirm theoretical predictions.

## Abstract

Unidirectional waves are the waves propagating only in one direction and prohibited in opposite direction. This kind of waves can be surface waves realized by topological edge state or bulk waves in the media with time reversal and space inversion symmetry broken. Here, we introduce unidirectional waveguide modes in the periodic dielectric chain comprised of gyromagnetic rods. In this modes, the waves in the waveguide propagates unidirectional, but can be converted into bi-directional waves by changing the arrangement of rods. We show unidirectional guided waves result from the time-mirror symmetry broken of the chain. Experiments confirm the theoretical results of waveguide modes. A new vortex wave generator based on the unidirectional guided wave is demonstrated theoretically. Our work opens a new avenue for manipulating the electromagnetic wave in a simple and flexible way, and provides a new possibility for novel devices.

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Source: https://tomesphere.com/paper/1902.08054