Exploitation of strong light-matter interactions in plasmonic systems is vital for both fundamental studies and the development of new applications, which enables exceptional physical phenomena and promotes potential applications in nanophotonics, information communication, and quantum information processing. Here, we present an analytic model of the interaction between localized surface plasmon resonances and excitons, where a semiclassical method is utilized. Two kinds of metal nanoparticles (nanosphere and nanoellipsoid) are considered in our study. We derive the relations between the plasmon-exciton coupling strength and the geometry and material parameters of the coupled systems when the nanoparticles are put in an excitonic medium, which give an important guide to achieve strong plasmon-exciton coupling. Rabi splittings and anticrossing behavior are also demonstrated in the calculated extinction spectra. Furthermore, we propose an analytic model to describe the strong coupling between excitons and plasmon in a core-shell nanorod structure which is widely used in experiments. Our study provides a simple yet rigorous prescription to both analyze and design plexcitonic systems aiming at strong light-matter interactions.

中文翻译：

---

等离子-激子相互作用从弱耦合到强耦合的半经典模型

利用等离激元系统中强大的光-质相互作用对于基础研究和新应用的开发都是至关重要的，这可以实现特殊的物理现象，并促进纳米光子学，信息通信和量子信息处理中的潜在应用。在这里，我们介绍了局部表面等离子体激元共振和激子之间相互作用的解析模型，其中利用了半经典方法。我们的研究考虑了两种金属纳米粒子（纳米球和纳米椭圆体）。我们推导了将纳米粒子置于激子介质中时等离激子-激子耦合强度与耦合系统的几何和材料参数之间的关系，这为实现强等离激子-激子耦合提供了重要指导。在计算的消光光谱中也证明了拉比分裂和抗交叉行为。此外，我们提出了一个解析模型来描述在核-壳纳米棒结构中激子与等离激元之间的强耦合，该模型在实验中被广泛使用。我们的研究提供了一个简单而严谨的处方，以分析和设计针对强光-物质相互作用的plexcitonic系统。