Meta-coupler arrays linking propagating waves and photonic topological modes on a chip

Photonic topological modes (PTMs) have attracted increasing attention due to their robust optical performance, which provides a defect-tolerant strategy for chip-integrated photonic systems. The current coupling schemes rely on bulky structures that severely limit their potential applications in high-density optical integration. Here, plasmonic metasurfaces loaded on topological waveguide arrays are explored to generate PTMs. The normally incident circularly polarized beam can be coupled into the topological interface or edge modes after carefully optimizing the metasurfaces. The result provides a compact and flexible method for PTMs generation on a chip, suggesting a promising avenue toward the application of topological photonic devices.