Focusing Micromechanical Polaritons in Topologically Nontrivial Hyperbolic Metasurfaces

• Published in: Advanced materials (Weinheim) Vol. 36; no. 25; pp. e2311599 - n/a
• Main Authors: Zheng, Jiang‐Po, Zheng, Li‐Yang, Yu, Si‐Yuan, Yang, Shi‐Li, Sun, Xiao‐Chen, Liu, Le, Lu, Ming‐Hui, Chen, Yan‐Feng, Christensen, Johan
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.06.2024
• Subjects: hyperbolic polaritons; Metamaterials; Metasurfaces; Polaritons; Thin films; topological insulators; van der Waals materials; van der Waals materials; metamaterials; polaritons; topological insulators; hyperbolic polaritons
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202311599

Vertically stacked multiple atomically thin layers have recently widened the landscape of rich optical structures thanks to these quantum metamaterials or van der Waals (vdW) materials, featuring hyperbolic polaritons with unprecedented avenues for light. Despite their far‐reaching implications, most of their properties rest entirely on a trivial band topological origin. Here, a 2D approach is adopted toward a micromechanical vdW analogue that, as a result of engineered chiral and mirror symmetries, provides topologically resilient hyperbolic radiation of mechanical vibrations in the ultrasonic regime. By applying laser vibrometry of the micrometer‐sized metasurface, we are able to exhibit the exotic fingerprints of robust hyperbolic radiation spanning several frequencies, which beyond their physical relevance, may enable ultrasonic technologies. The study takes a micromechanical approach to unlock topologically resilient vibrating polaritons in analog to van der Waals nanophotonics. It is shown that due to the embedded topological protection, hyperbolic focused radiation remains resilient against random defects.