Abstract

Within the framework of the geometric optics model, an algorithm is developed for calculating the trajectories of oblique rays (hybrid modes) in an optical fiber with a step-index profile. The first (three-dimensional) version of the algorithm reduces to the sequential calculation of the coordinates of the ray reflection points in vector form, the second (two-dimensional) version – to the independent calculation of the transverse coordinates of the reflection points followed by the calculation of the longitudinal (axial) coordinate. The calculation results obtained by the two versions of the algorithm are the same. Using the developed algorithm, the trajectories of oblique rays in an optical fiber with a core diameter of 400 μm were simulated under various excitation conditions. The projections of ray trajectories onto the output face of the fiber are calculated. The characteristic topological form of projections is an envelope ring, the inner boundary of which defines the caustic. “Resonant” types of projections of ray trajectories are identified. The calculation algorithm was tested in experiments on the excitation of oblique rays (λ = 532 nm) in quartz-polymer optical fiber with a core diameter of 400 and 600 μm.

中文翻译：

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阶跃折射率光纤中倾斜光线轨迹的仿真

摘要

在几何光学模型的框架内，开发了一种算法，用于计算具有阶跃折射率分布的光纤中的斜光线（混合模式）的轨迹。该算法的第一个（三维）版本简化为以矢量形式顺序计算射线反射点的坐标，第二个（二维）版本 – 简化为随后独立计算反射点的横向坐标通过计算纵（轴）坐标。两个版本的算法得到的计算结果是相同的。使用开发的算法，在各种激励条件下模拟了纤芯直径为 400 μm 的光纤中的斜光线轨迹。计算光线轨迹在光纤输出面上的投影。投影的特征拓扑形式是包络环，其内部边界定义焦散。确定了射线轨迹投影的“共振”类型。该计算算法在纤芯直径为400和600 μm的石英聚合物光纤中进行斜射线（λ = 532 nm）激发实验测试。