Higher-order topological insulators, as a novel family of topological phases, are a hot frontier in condensed-matter physics and classical waves due to their adherence to unconventional bulk-boundary correspondence. A three-dimensional second-order topological insulator can support one-dimensional modes along its hinges (dubbed “hinge states”). Here, we present a simple and direct method to construct chiral hinge modes based on a Chern-insulator stack. We analyze the existence of the hinge modes through the nontrivial quadrupole indices and then design a photonic antiferromagnetic crystal to realize the specific flowing pattern of the hinge mode in our model. The experimental results align well with full-wave simulations, clearly demonstrating the existence of chiral hinge states. We also verify the robustness of these hinge states against defects in our photonic system.

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• Chern insulators
• Photonic crystals
• Topological insulators