From butterfly wings to topological photonic crystal waveguides and cavities

As periodic dielectric structures, photonic crystals allow for the free manipulation of electromagnetic waves and have already demonstrated significant potential in fields such as optical communication and sensing. However, due to inevitable manufacturing defects, electromagnetic waves in photonic crystals suffer significant scattering loss; this not only degrades the performance of optical waveguides but also limits the quality factor of photonic crystal microcavities. In recent years, topological states of matter—renowned for their robustness—have provided a new approach for the control of electromagnetic waves, giving rise to an emerging field known as topological photonics. This paper briefly reviews the development of topological photonic crystals, with particular focus on the latest research on the ability of topological waveguides and microcavities to enhance light control. These findings not only deepen our understanding of the interactions between light and matter but also pave the way for the design of future high-performance photonic integrated chips.