Self-hybridized exciton–polaritons in perovskite-based subwavelength photonic crystals

Self-coupled photonic resonators made of exciton materials have recently provoked great interest in the context of light–matter interactions due to their ability to produce large normal mode splittings. In order to obtain giant Rabi energy, it is rather necessary to ensure large electromagnetic fields within exciton materials. Here, using two independent numerical algorithms, namely, the finite-element method and the rigorous coupled wave analysis, we demonstrate that, even with a moderate oscillation strength, giant Rabi splittings in excess of 250 meV can be achieved in subwavelength perovskite-based photonic crystals. This can be attributed to the fact that quasi-guided resonance modes supported by photonic systems are strongly confined inside the exciton material, highly conducing to increasing the volume of light–matter interaction. We reveal how the oscillator strength of excitons and the thickness of perovskite photonic crystals influence photon–exciton couplings. Moreover, the perovskite nanostructures investigated allow us to engineer polaritonic dispersions with linear or slow-light characters. These findings show that perovskite-based photonic crystals could be an appealing and promising platform in realizing polaritonic devices.