Research into topological photonic metamaterials, led by City College of New York, shows that long-range interactions in metamaterials can change the behavior of lightwaves, forcing the waves to localize in space. The study further shows that by controlling the degree of these interactions, the character of the lightwaves can be switched from propagating to trapped. This discovery could lead to new ways to speed online data transfer, according to the researchers. Photonic topological insulators enable topological boundary modes that are resilient to defects and disorder, irrespective of manufacturing precision. This property is known as topological protection. Higher-order topological insulators (HOTIs) offer topological protection over an extended range of dimensionalities. The researchers introduced a photonic HOTI with kagome lattice that exhibited topological bulk polarization. This led to the emergence of one-dimensional edge states and higher-order zero-dimensional states, which were confined to the corners of the structure. In addition to the corner states due to nearest-neighbor interactions, the researchers discovered a new class of topological corner states induced by long-range interactions and specific to photonic systems. Their findings could open new opportunities for engineering new electromagnetic states with a high degree of topological robustness. Light localized in space inside the topological crystal, entangled by interaction and topology. Courtesy of ITMO University. “The new approach to trap light allows the design of new types of optical resonators, which may have a significant impact on devices used on a daily basis,” professor Alexander B. Khanikaev said. “These range from antennas in smartphones and Wi-Fi routers to optical chips in optoelectronics used for transferring data over the internet with unprecedented speeds.” The research is a collaboration between the Photonics Initiative at the Graduate Center at City University of New York (CUNY) and ITMO University. The team continues to explore this new approach to trap visible and infrared light. The research was published in Nature Photonics (www.doi.org/10.1038/s41566-019-0561-9).