Thanks to their giant, yet tunable, Q-factor resonances, all-dielectric metasurfaces supporting the quasi-bound states in the continuum (q-BIC) resonances are well-suited to provide a promising platform for quantum-coherent light–matter interactions. Yet, the strong coupling regime, characterized by the hybrid light–matter states – polaritons, has not yet been fully explored in the mid-infrared regime. This paper investigates the parameter space of vibrational strong coupling (VSC) between material and metasurface cavities supporting q-BIC resonances in the mid-infrared spectral range. We outline the effects of transition dipole strength, damping rate, and the number of molecules coupled to a single cavity, as well as the cavity damping rates, to understand their respective impacts on VSC. By tuning the Q-factor of the metasurface and material parameters, a new transition light–matter coupling zone is introduced, bridging the gap between weak and strong coupling, where polaritons form but their linewidths prohibit their spectral identification. The study further identifies the effects of cavity linewidth on polariton peak separability in strongly coupled systems, highlighting that the cavities with smaller nonradiative losses and narrower linewidths facilitate better polariton separability. Moreover, we found that matching cavity and material loss, satisfying the critical strong coupling condition, enhances the coupling strength between cavity and material. Overall, these findings can guide the design of photonic cavities suited for VSC experiments, contributing to the burgeoning fields of polaritonic chemistry, light-mediated modulation of chemical reactivity, and highly sensitive molecular spectroscopy.

中文翻译：

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从弱耦合到强耦合：用于中红外光-物质相互作用的准 BIC 超表面

感谢他们巨大但可调的，问因子共振，支持连续体（q-BIC）共振中的准束缚态的全介电超表面非常适合为量子相干光与物质相互作用提供有前途的平台。然而，以光-物质混合态——极化子为特征的强耦合机制在中红外机制中尚未得到充分探索。本文研究了支持中红外光谱范围内 q-BIC 共振的材料和超表面空腔之间的振动强耦合 (VSC) 参数空间。我们概述了过渡偶极子强度、阻尼率、耦合到单个腔的分子数量以及腔阻尼率的影响，以了解它们各自对 VSC 的影响。通过调整问-超表面和材料参数的因素，引入了一个新的过渡光-物质耦合区，弥合了弱耦合和强耦合之间的差距，其中极化激元形成，但其线宽阻碍了它们的光谱识别。该研究进一步确定了强耦合系统中腔线宽对极化子峰可分离性的影响，强调非辐射损耗较小和线宽较窄的腔有利于更好的极化子可分离性。此外，我们发现匹配腔体和材料损耗，满足临界强耦合条件，增强了腔体和材料之间的耦合强度。总的来说，这些发现可以指导适合 VSC 实验的光子腔的设计，为极化子化学、光介导的化学反应性调制和高灵敏度分子光谱学等新兴领域做出贡献。