Parity-time (PT) symmetry has attracted intensive research interest in recent years. PT symmetry is conventionally implemented between two spatially distributed subspaces with identical localized eigenfrequencies and complementary gain and loss coefficients. The implementation is complicated. In this paper, we propose and demonstrate that PT symmetry can be implemented between two subspaces in a single spatial unit based on optical polarimetric diversity. By controlling the polarization states of light in the single spatial unit, the localized eigenfrequencies, gain, loss, and coupling coefficients of two polarimetric loops can be tuned, leading to PT symmetry breaking. As a demonstration, a fiber ring laser based on this concept supporting stable and single-mode lasing without using an ultranarrow bandpass filter is implemented.

近年来，宇称时间（PT）对称性引起了人们广泛的研究兴趣。PT对称性通常在具有相同局部特征频率和互补增益和损耗系数的两个空间分布的子空间之间实现。实施起来很复杂。在本文中，我们提出并证明了基于光学偏振分集，可以在单个空间单元中的两个子空间之间实现 PT 对称性。通过控制单个空间单元中光的偏振态，可以调节两个偏振环的局部本征频率、增益、损耗和耦合系数，从而导致 PT 对称性破缺。作为演示，实现了基于此概念的光纤环形激光器，无需使用超窄带通滤波器即可支持稳定的单模激光。