Hybrid magneto-excitonic polariton metastructures: room-temperature strong coupling in all-oxide platforms

Abstract

Breaking optical reciprocity at room temperature in a fully dielectric platform remains a demanding yet impactful goal for integrated photonics. In this work we design and numerically demonstrate a lithography-defined, all-oxide metastructure that merges ferrimagnetic CoFe₂O₄ nanodisks with Mn-doped ZnO (ZnO:Mn) nanodisks, separated by a sub-2 nm Al₂O₃ spacer. This geometry, refined through detailed parameter sweeps and alignment tolerances captured in our original design notes, supports hybrid magneto-exciton polaritons with Rabi splittings up to 120 meV and cooperativity factors exceeding 5 at 300 K—without cryogenics or metallic losses. Finite-difference time-domain and micromagnetic simulations, combined with coupled-mode modelling, reveal broadband (>20 nm) bias-tunable nonreciprocal transmission windows whose spectral positions can be engineered via geometry, Mn content, and interlayer spacing. Our findings validate the concept sketched in the initial design drafts: an oxide-exclusive, CMOS-compatible platform delivering bias-reconfigurable spin–photon coupling, scalable fabrication, and chemical-thermal stability. The approach bridges fundamental magneto-optical physics with practical on-chip implementations, offering a clear pathway toward energy-efficient isolators, routers, and phase-controlled photonic components operating at ambient conditions.