Structured light with isolated complex $\pi$-symmetric polarization singular topologies such as lemon, star, and monstar is experimentally generated using few-mode optical fiber (FMF). These singularities, popularly known as C-points, are generated in the fiber modal field as a result of an inherent combination of orthogonally polarized Gaussian and vortex modes, excited simultaneously in FMF and controlled by input coupling conditions. The vortex charge, the state of polarization of the combining modes, and the relative phase difference between them are analyzed using Stokes polarimetry. Further, modal fields consisting of two opposite/similar index C-points are also generated, and the possible mode combinations that are responsible for such complex patterns are discussed. The helicity and index conservations in formation of dipoles also are discussed.

中文翻译：

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少模光纤模场中的偏振奇异图案

具有隔离的复杂$ \ pi $的结构光对称偏振偏振奇异拓扑（例如柠檬，星和孟斯塔）是使用少模光纤（FMF）通过实验生成的。这些奇异点（通常称为C点）是由于正交极化的高斯模和涡模的固有组合而在光纤模场中生成的，它们在FMF中同时激发并受输入耦合条件控制。使用斯托克斯极化仪分析了涡旋电荷，组合模式的极化状态以及它们之间的相对相位差。此外，还生成了由两个相对/相似的索引C点组成的模态字段，并讨论了导致这种复杂模式的可能的模态组合。还讨论了偶极子形成中的螺旋度和指数守恒性。