Integrated Array of Coupled Exciton-Polariton Condensates

A central challenge for advancing polariton-based circuits is the controlled and scalable coupling of individual condensates. Existing approaches based on etched or epitaxially grown microcavities are fabrication-intensive and restrict in-plane coupling. To overcome these limitations, we introduce a lithographically defined silicon-based platform of high-contrast grating (HCG) microcavities, integrated with spin-coated methyl-ladder poly(para-phenylene). In this system, doublet cavities display mode hybridization into binding and antibonding states, with coupling across shared HCG mirrors. Extending the design to arrays, N-coupled condensates exhibit systematic redshifts of the condensate energy and progressive threshold reduction, consistent with extended binding modes. These experimental results are quantitatively supported by transition-matrix multi-scattering simulations, together with tight-binding modelling. Finally, first-order coherence measurements using Michelson interferometry confirm spatially extended condensates with temporal coherence following an exponential decay. Together, these results establish a scalable route toward integrated polariton devices and quantum photonic networks.