The emergence of dielectric open optical cavities has opened a new research avenue in nanophotonics. In particular, dielectric microspheres support a rich set of cavity modes with varying spectral characteristics, making them an ideal platform to study molecule–cavity interactions. The symmetry of the structure plays a critical role in the outcoupling of these modes and, hence, the perceived molecule–cavity coupling strength. Here, we experimentally and theoretically study molecule–cavity coupling mediated by the Mie scattering modes of a dielectric microsphere placed on a glass substrate and excited with far-field illumination, from which we collect scattering signatures both in the air and glass sides. Glass-side collection reveals clear signatures of strong molecule–cavity coupling (coupling strength 2g = 74 meV), in contrast to the air-side scattering signal. Rigorous electromagnetic modeling allows us to understand molecule–cavity coupling and unravel the role played by the spatial mode profile in the observed coupling strength.

中文翻译：

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对称破缺在使用介电微球观察强分子-腔耦合中的作用

电介质开放光学腔的出现为纳米光子学开辟了新的研究途径。特别是，介电微球支持一组具有不同光谱特性的丰富腔模式，使其成为研究分子-腔相互作用的理想平台。结构的对称性在这些模式的外耦合中起着关键作用，因此，感知到的分子-腔耦合强度。在这里，我们在实验和理论上研究了由放置在玻璃基板上并用远场照明激发的介电微球的 Mie 散射模式介导的分子-腔耦合，我们从中收集空气和玻璃侧的散射特征。玻璃侧收集揭示了强分子-腔耦合的清晰特征（耦合强度 2 g= 74 meV），与空气侧散射信号相反。严格的电磁建模使我们能够理解分子-腔耦合并揭示空间模式分布在观察到的耦合强度中所起的作用。