Observation of robust polarization conversion via topological edge states in dimer chains

Abstract The polarization of electromagnetic waves is a fundamental property that influences their propagation direction and state, represents a critical physical parameter in modern applications such as signal transmission, target recognition, and precision measurement. Conventional polarization control devices based on metamaterials are often sensitive to structural perturbations, presenting challenges for practical applications. In contrast, topologically protected photonic devices have demonstrated that photon topological edge states can effectively overcome scattering losses caused by disorder and structural perturbations. The prospect of utilizing the robustness of topological edge states to design reliable electromagnetic wave polarization devices has thus become an increasingly significant research focus. We design and construct a curved photonic dimer chain composed of subwavelength resonators and experimentally verify that its topological edge states are immune to internal disorder perturbations, enabling efficient long-range electromagnetic wave polarization conversion. Based on this study, future investigations could explore more complex topological architectures, such as quasiperiodic or trimer chains, to achieve enhanced multifunctional polarization control. Furthermore, we could consider integrating exceptional points in non-Hermitian systems to design chiral polarization devices.