Control of coupling between micromechanical topological waveguides

• Published in: International journal of mechanical sciences 2022-12, Vol.236, p.107755, Article 107755
• Main Authors: Funayama, Keita, Yatsugi, Kenichi, Miura, Atsushi, Iizuka, Hideo
• Format: Article
• Language: English
• Subjects: coupled waveguides; micro electromechanical systems; Topological insulators
• ISSN: 0020-7403; 1879-2162
• DOI: 10.1016/j.ijmecsci.2022.107755

•Demonstration of coupling between micro electromechanical systems-based topological waveguides.•Coupling strength was widely controlled by the physical distance.•The design of localization length enables fine tuning for coupling. Topological waveguides exhibit intriguing wave-phenomena such as one-way energy propagation with forbidden backscattering and immunity to defects. Understanding of the coupling behavior between two topological waveguides and controlling the coupling strength are of great importance towards largely integrated multiple-topological waveguides. However, qualitative and systematic investigations on coupling between topological waveguides have been insufficient yet. Here we experimentally investigate the tunability of coupling phenomena between topological waveguides by using the well-established micro electromechanical systems (MEMS). Wide tuning-range of the coupling strength is obtained by adjusting the physical distance between the waveguides, where the distance is limited to have discrete values due to the nature of the periodic structure. Fine-tuning of the coupling strength is obtained by adjusting the confinement of the elastic energy, i.e., localization length in the waveguide. The experimental results agreed with numerical results obtained by using a finite element method simulator. Combining the two approaches leads to wide and fine tunability, and is the crucial methodology towards large-scale integrated topological circuits and systems. [Display omitted]