Cavity-controlled Topological Phase Transitions in Dipolar Arrays Via Asymmetric Design

Topological phase transitions in photonic systems are traditionally realized by geometrically modifying the unit cell. Here, we introduce a cavity-based mechanism that enables dynamic control of topological phases without structural alterations. Specifically, we study the topological phase of electric dipolar arrays placed between two parallel metal plates. Using the image-charge method, we demonstrate that the coupling strength between dipoles is strongly influenced not only by their distances to the two plates but also by the orientation of the dipoles themselves. Exploiting this feature, we construct an equally spaced Su-Schrieffer-Heeger (SSH) chain composed of dipoles with tailored orientations. We show that when the chain is closer (farther) to the top plate than to the bottom plate, the system exhibits a topologically trivial (nontrivial) phase. Hence, the topological phase of the array can be controlled simply by tuning the relative position of the chain between the two plates. We further generalize this approach to two-dimensional dipolar arrays, demonstrating its applicability to a Kagome lattice. This cavity-enabled strategy offers a practical route for achieving topological phase transitions in photonic systems without the need for lattice geometry modification, paving the way for more versatile implementations of topological photonics.