Enhancement of Light–Matter Interaction Induced by Quantum‐Coherent Coupling Between Localized Surface Plasmon Resonance and Volume Plasmon Polariton

Abstract Hyperbolic metamaterials (HMMs) are known for their robust light–matter interaction and ability to generate volume plasmon polaritons (VPPs). Au nanoparticles (Au NPs) enable to enhance this interaction through localized surface plasmon resonance (LSPR), creating intense local electric fields. However, combining LSPR and VPPs in one device remains unexplored. This study proposes and demonstrates Au NP‐coupled‐HMMs (NPCHMMs), integrating Au NPs with HMMs to enhance random laser action and lower the lasing threshold. NPCHMMs boost emission intensity by ≈6 times compared to pure HMMs, with a ≈47% reduction in lasing threshold. Based on Fermi's golden rule, the calculated transition rate in NPCHMMs surpasses the algebraic sum of the individual transition rates derived from HMMs and Au NPs. It reveals the effect of the coherent coupling between the transition matrix elements of VPP and LSPR. This research indicates that NPCHMMs are a promising platform to create high‐performance optical and optoelectronic devices, such as lasers and phototransistors, for a wide range of application in many fields.