The dynamical encirclement around a second-order exceptional point (EP) and corresponding chirality driven nonadiabatic modal dynamics have attracted enormous attention in the topological study of various non-Hermitian systems. However, dynamical encirclement around multiple second-order EPs in a multistate system is yet to be explored. Here, exploiting an exclusive design of a planar gain-loss assisted three-mode supported optical waveguide with local Kerr nonlinearity, we encounter multiple second-order EPs. Judiciously, choosing a specific parameter space by varying the unbalanced gain-loss profile, we encircle multiple EPs simultaneously, and explore the beam dynamics toward corresponding chiral or nonchiral aspects of the device. While propagating through the designed waveguide, three coupled modes are collapsed into a specific dominating mode, owing to corresponding nonadiabatic corrections around multiple EPs. We reveal that in the absence of chirality the same amount of focusing- and defocusing-type nonlinearity gives different dominating output, irrespective of the choice of inputs, for the same topological structure of the waveguide. An analytical model to describe this anomalous mode collapsing phenomenon due to interplay between nonlinearity and the EP has been developed. Our findings should provide a promising opportunity to switch or retrieve a selective mode from a multimode signal in integrated devices.

中文翻译：

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非线性引起的异常模式崩溃和围绕多个异常点的非手性非对称模式切换

在各种非Hermitian系统的拓扑研究中，围绕二阶例外点（EP）的动力学包围和相应的手性驱动的非绝热模态动力学引起了极大的关注。然而，在多状态系统中围绕多个二阶EP的动态包围尚待探索。在这里，利用具有局部Kerr非线性的平面增益损耗辅助三模支持光波导的独家设计，我们遇到了多个二阶EP。明智地，通过改变不平衡的增益-损耗曲线来选择特定的参数空间，我们同时环绕多个EP，并探索朝向设备相应手性或非手性方面的光束动力学。通过设计的波导传播时，由于围绕多个EP进行了非绝热校正，三种耦合模式被折叠为特定的主导模式。我们揭示了在没有手征性的情况下，对于波导的相同拓扑结构，无论输入选择如何，相同数量的聚焦和散焦类型的非线性都会提供不同的主导输出。已经开发了一种分析模型来描述这种由于非线性和EP之间的相互作用而导致的异常模式崩溃现象。我们的发现应该为从集成设备中的多模信号切换或检索选择模式提供一个有前途的机会。对于波导的相同拓扑结构，无论输入选择如何。已经开发了一种分析模型来描述这种由于非线性和EP之间的相互作用而导致的异常模式崩溃现象。我们的发现应该为从集成设备中的多模信号切换或检索选择模式提供一个有前途的机会。对于波导的相同拓扑结构，无论输入选择如何。已经开发了一种分析模型来描述这种由于非线性和EP之间的相互作用而导致的异常模式崩溃现象。我们的发现应该为从集成设备中的多模信号中切换或恢复选择模式提供一个有前途的机会。