Robustness in Subwavelength Locally-Resonant Metamaterial Waveguides

Guiding electromagnetic energy at a subwavelength scale is one of the most highly demanded functionalities in a variety of applications, including compact, lightweight satellite communications, signal and data processing, and power systems. The existing schemes for subwavelength waveguiding, including topological designs, are usually based on the use of locally resonant metamaterials and generally sensitive to the lattice imperfections and disorder-induced backscattering. We quantitatively assess here the robustness of subwavelength edge modes in different waveguide designs, including designs based on C6 symmetry or valley-Hall (VH) topological insulators (TI) and non-topological designs based on chirality or a frequency defect line. The statistical results demonstrate that all waveguiding schemes provide a different level of robustness of the edge modes for different types of disorder and superior robustness of VH and chiral metamaterial waveguides to all three types of disorder.