片上可集成的拓扑微纳光子器件 (特邀)

Significance Topological nanophotonics can endow photonic devices with inherent, mathematically protected robustness. By designing photonic structures with topologically nontrivial band structures and utilizing mechanisms such as the photonic quantum Hall, photonic quantum spin Hall, or valley Hall effects, protected transport states are generated at their boundaries or interfaces. The existence of these states is guaranteed by global topological invariants. Their propagation exhibits strong immunity to local structural disorder and bends of arbitrary shapes, enabling near-zero-loss light transmission and stable optical modes. This significantly relaxes the stringent requirements on fabrication precision and surpasses the bending limits of conventional waveguides, thereby removing critical barriers for high-density, high-reliability on-chip photonic integration. Progress First, various topological phases from condensed matter physics, including the quantum Hall effect, quantum spin Hall effect, and valley Hall effect, were analogously introduced into photonic systems, constructing a rich theoretical framework for topological photonics. Then, based on these physical principles, a variety of integrable on-chip topological micro/nano photonic devices, such as topological waveguides and resonant cavities, were developed, and their core advantages, including defect robustness, backscattering immunity, and low-loss transmission—were experimentally validated. Finally, the field is rapidly advancing from single physical mechanisms toward the deep integration of multiple physical concepts, such as non-Hermitian physics and synthetic dimensions, and evolving from passive transmission to functionalization, active control, and intelligent algorithm-based design. This progress offers novel solutions to address the bottleneck challenges in large-scale photonic integration. Conclusions and Prospects Leveraging their topological protection properties, topological nanophotonic devices can significantly suppress backscattering and losses induced by fabrication imperfections and material disorder. Thereby, they address critical bottlenecks—including optical scattering, crosstalk, and poor robustness, that hinder the integration of traditional micro-nano photonic devices, offering revolutionary solutions for realizing high-performance, highly reliable on-chip optical systems. Future research in this field will increasingly focus on the deep integration of multiple physical concepts and intelligent design. On one hand, researchers will explore novel topological states, for instance, by combining concepts such as Floquet theory, non-Hermitian physics, and synthetic dimensions and apply them to device design to achieve more flexible control of optical fields. Simultaneously, efforts will be dedicated to tackling core challenges including the optimization of high-performance devices, large-scale scalable integration, and compatibility with optical quantum systems. On the other hand, integration with emerging two-dimensional materials and phase-change materials holds promise for realizing lower-power, highly integrated multifunctional active topological devices. These cutting-edge explorations will collectively drive topological photonic technologies from laboratory research toward practical applications, laying a solid foundation for next-generation industrial fields such as integrated optical quantum computing, high-speed optical communication, and ultra-sensitive sensing.