Bisyarin M A, Kotov O I, Hartog A H, Liokumovich L B, Ushakov N A
Appl Opt. 2016 Jul 1;55(19):5041-51. doi: 10.1364/AO.55.005041.
Rayleigh backscattering produced by an incident fundamental mode in a multimode optical fiber is analyzed using a diffraction technique, with a full set of backward-propagating modes being taken into consideration. Explicit formulas are derived for mode excitation efficiency via radial distributions of the mode fields, and it is proved that only half-azimuthal modes are backscattered by the incident wave of a fixed polarization. Advanced analytical expressions are developed for fibers with a quadratic refractive-index profile, and mode groups of even numbers, composed of modes with equal propagation constants, are stated to be excited with equal efficiencies.
利用衍射技术分析了多模光纤中入射基模产生的瑞利背向散射，并考虑了完整的反向传播模式集。通过模式场的径向分布推导出了模式激发效率的显式公式，并证明了对于固定偏振的入射波，只有半方位角模式会发生背向散射。针对具有二次折射率分布的光纤，推导了高级解析表达式，并指出由具有相等传播常数的模式组成的偶数模式组以相等的效率被激发。
