AI 中文总结
本文研究具有平衡增益损耗和频率相关芯间耦合的克尔双芯耦合器中，色散耦合将PT对称转为CPT对称，分析简并四波混频的共振通道，近阈值处单个泵浦可同时满足两个非零边带共振，异常点区域少模描述会失效。
AI 中文摘要
四波混频提供了一个简单的场景，其中色散、非线性和非厄米性相互竞争以选择共振能量转移通道。我们研究了克尔双芯耦合器中的简并四波混频，该耦合器具有平衡增益损耗和频率相关的芯间耦合。色散耦合将对称性从传统的PT对称转变为组合的CPT对称，并重塑了双分支线性谱。我们确定了未破缺的CPT域，并对可满足简并相位匹配条件的分支构型进行分类。在所研究的参数范围内，三个共振通道在宽区域内持续存在，而同分支通道仅在对称破缺阈值附近出现。在该近阈值区域，单个泵浦可同时满足两个不同的非零边带共振。直接脉冲模拟证实了预测的共振，并揭示了本征模合并附近的次波产生和多频级联。简化的三波模型捕捉了远离异常点的初始动力学，但随着模基变得病态，其准确性下降。这些结果表明色散耦合如何在非厄米波系统中重组共振、群速度失配和非线性能量交换，并将异常点区域识别为少模描述可能失效的区域。
英文摘要
Four-wave mixing provides a simple setting in which dispersion, nonlinearity, and non-Hermiticity compete to select resonant energy-transfer channels. We study degenerate four-wave mixing in a Kerr dual-core coupler with balanced gain and loss and frequency-dependent intercore coupling. The dispersive coupling changes the symmetry from conventional $\mathcal{PT}$ symmetry to a combined $\mathcal{CPT}$ symmetry and reshapes the two-branch linear spectrum. We determine the unbroken-$\mathcal{CPT}$ domain and classify the branch configurations that can satisfy the degenerate phase-matching condition. In the parameter ranges examined, three resonant channels persist over broad regions, whereas a same-branch channel appears only close to the symmetry-breaking threshold. In this near-threshold regime, a single pump can simultaneously satisfy two distinct nonzero sideband resonances. Direct pulse simulations confirm the predicted resonances and reveal secondary-wave generation and multifrequency cascades near eigenmode coalescence. A reduced three-wave model captures the initial dynamics away from the exceptional point but loses accuracy as the modal basis becomes ill-conditioned. These results show how dispersive coupling reorganizes resonances, group-velocity mismatch, and nonlinear energy exchange in a non-Hermitian wave system, and they identify the exceptional-point region as a regime where a few-mode description can break down.
Comments16 pages, 11 figures, submitted for publication
