Magnetically controllable multimode interference in topological photonic crystals

Weiyuan Tang; Mudi Wang; Shaojie Ma; Che Ting Chan; Shuang Zhang

doi:10.1038/s41377-024-01433-1

Magnetically controllable multimode interference in topological photonic crystals

Light Sci Appl. 2024 May 14;13(1):112. doi: 10.1038/s41377-024-01433-1.

Authors

Weiyuan Tang^#¹, Mudi Wang^#², Shaojie Ma^{1

3}, Che Ting Chan⁴, Shuang Zhang⁵

Affiliations

¹ New Cornerstone Science Laboratory, Department of Physics, The University of Hong Kong, Hong Kong, China.
² Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
³ Department of Optical Science and Engineering, Fudan University, Shanghai, 200433, China.
⁴ Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China. phchan@ust.hk.
⁵ New Cornerstone Science Laboratory, Department of Physics, The University of Hong Kong, Hong Kong, China. shuzhang@hku.hk.

^# Contributed equally.

Abstract

Topological photonic insulators show promise for applications in compact integrated photonic circuits due to their ability to transport light robustly through sharp bendings. The number of topological edge states relies on the difference between the bulk Chern numbers across the boundary, as dictated by the bulk edge correspondence. The interference among multiple topological edge modes in topological photonics systems may allow for controllable functionalities that are particularly desirable for constructing reconfigurable photonic devices. In this work, we demonstrate magnetically controllable multimode interference based on gyromagnetic topological photonic insulators that support two unidirectional edge modes with different dispersions. We successfully achieve controllable power splitting in experiments by engineering multimode interference with the magnetic field intensity or the frequency of wave. Our work demonstrates that manipulating the interference among multiple chiral edge modes can facilitate the advancement of highly efficient and adaptable microwave devices.