Mitigating Lithography Stitching Losses Using Topological Photonic Crystals in Silicon Photonics

ABSTRACT Topological photonic crystals (TPCs) have attracted extensive attention for their ability to support robust, backscattering‐immune light propagation, offering a promising path toward high‐performance, large‐scale photonic integration systems. Although significant progress has been made in elucidating the fundamental topological properties and developing innovative TPC‐based devices, their potential to overcome practical challenges remains largely unexplored. Here, we take a substantial step forward by leveraging the topological protection inherent to TPCs to mitigate stitching losses caused by lithography field misalignment. We design and experimentally demonstrate a topological valley photonic crystal (VPC) waveguide on the silicon‐on‐insulator (SOI) platform. Compared with a conventional 0.5 µm‐wide waveguide, the proposed VPC waveguide reduces stitching losses from 0.59 to 0.009 dB and from 1.53 to 0.54 dB under 100 nm lateral and longitudinal field misalignments at a wavelength of 1550 nm, corresponding to reductions of 98.3% and 64.7%, respectively. The robustness of VPC waveguides persists even under severe misalignments of up to 500 nm, equivalent to the width of a conventional waveguide. These findings not only highlight the practical viability of TPCs under realistic fabrication constraints but also pave the way for large‐scale, fabrication‐resilient photonic integration.