Tailored Tight‐Binding Couplings in Photonic Crystals

ABSTRACT The tight‐binding (TB) model offers a versatile framework for exploring novel photonic phenomena. Its faithful implementation in photonic crystals (PCs), however, requires not only suppressed long‐range couplings but also systematic and scalable control over both the magnitude and the sign of inter‐site couplings. Here, it is demonstrated periodic defect arrays embedded in a photonic band‐gap host as a PCs platform for programmable engineering of TB couplings. The localized defect modes provide an accurate TB description, and by adjusting either the number or the detuning of spacer sites, it is achieved flexible control of the coupling strength together with a robust, parity‐protected reversal of its sign without modifying the defect sites themselves. Numerical simulations confirm that this strategy reproduces the target TB Hamiltonian with high fidelity and greatly expands the accessible design space beyond that of conventional PCs. As proof of concept, a 2D Su–Schrieffer–Heeger lattice that undergoes the predicted topological transition and a nonsymmorphic structure supporting Möbius edge states are implemented. This work provides a versatile and scalable route to TB‐inspired phenomena in PCs.