Cross-polarization coupling (CPC) between coresonant orthogonally polarized modes in a single whispering-gallery microresonator can lead to induced transparency effects. Depending on the CPC strength, coupled-mode-induced transparency (CMIT) or Autler-Townes splitting (ATS) can be observed. Determining the CPC strength is crucial in locating the exceptional point, where CMIT evolves into ATS and an enhancement in sensitivity to perturbations is expected. The CPC strength can be calculated theoretically based on the transverse structure of whispering-gallery modes. Experimentally, however, CPC strength has been inferred only indirectly by fitting the experimental throughput spectrum to a steady-state model. In this work, we propose and demonstrate a direct determination of the CPC strength based on the response of the throughput to a sinusoidal amplitude modulation of the input light. Our experimental results agree with numerical fitting values and are in the same range as predicted by theoretical calculations.

中文翻译：

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回音壁微谐振器中交叉极化耦合强度的动态测定

单个回音壁微谐振器中的共谐振正交极化模式之间的交叉极化耦合 (CPC) 会导致诱导透明效应。根据 CPC 强度，可以观察到耦合模式诱导的透明度 (CMIT) 或奥特勒-汤斯分裂 (ATS)。确定 CPC 强度对于定位异常点至关重要，在该点 CMIT 演变为 ATS 并且预计对扰动的敏感性会增强。CPC 强度可以基于回音壁模式的横向结构进行理论上的计算。然而，在实验上，CPC 强度只能通过将实验吞吐量谱拟合到稳态模型来间接推断。在这项工作中，我们建议并演示了基于吞吐量对输入光的正弦调幅的响应的 CPC 强度的直接确定。我们的实验结果与数值拟合值一致，并且与理论计算预测的范围相同。