An analytical model for estimating the stress -induced birefringence in true Panda-type polarization -maintaining fibers with imperfect geometry has been developed in this letter. The developed model is simpler and more accurate compared to conventional sophisticated and asymptotic formulas in reported works. Our model provides a clear and simple solution to demonstrate the periodic dependence of the birefringence on the misalignment angle between the two stress-applying parts, and the monotonic dependence on the geometric parameters of stress-applying parts. Our work also reveals the important role of the misalignment angle between the two stress-applying parts in practical Panda-type fibers.

中文翻译：

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熊猫型保偏光纤中应力诱导双折射的解析估计

在这封信中开发了一种用于估计具有不完美几何形状的真正熊猫型保偏光纤中应力引起的双折射的分析模型。与报告作品中传统的复杂渐近公式相比，开发的模型更简单、更准确。我们的模型提供了一个清晰而简单的解决方案，以证明双折射对两个施力部件之间未对准角度的周期性依赖性，以及对施力部件几何参数的单调依赖性。我们的工作还揭示了实际熊猫型光纤中两个应力施加部分之间的错位角的重要作用。