Fingerprints of topological defects in a metasurface

Singularity, representing a structurally stable topological defect (TD), plays a pivotal role in various physical systems. Here we theoretically present the fingerprints of TDs and uncover the resulting exotic optical properties in a tailored metasurface system. The presence of the TDs results in coherent perfect absorption, and dramatic optical property transition from slow to superluminal light behavior when the parameters cross the TD. Our investigation provides a new route to explore many phenomena of the TDs, extends the capabilities of metasurface, and offers benefits to develop potential nanophotonic applications based on the design of the metasurface.