Messica A, Greenstein A, Katzir A
Appl Opt. 1996 May 1;35(13):2274-84. doi: 10.1364/AO.35.002274.
A general theory for fiber-optic, evanescent-wave spectroscopy and sensors is presented for straight, uncladded, step-index, multimode fibers. A three-dimensional model is formulated within the framework of geometric optics. The model includes various launching conditions, input and output end-face Fresnel transmission losses, multiple Fresnel reflections, bulk absorption, and evanescent-wave absorption. An evanescent-wave sensor response is analyzed as a function of externally controlled parameters such as coupling angle, f number, fiber length, and diameter. Conclusions are drawn for several experimental apparatuses.
提出了一种适用于直的、无包层、阶跃折射率、多模光纤的光纤倏逝波光谱学及传感器的通用理论。在几何光学框架内建立了三维模型。该模型包括各种发射条件、输入和输出端面的菲涅耳传输损耗、多次菲涅耳反射、体吸收和倏逝波吸收。分析了倏逝波传感器响应作为诸如耦合角、f数、光纤长度和直径等外部控制参数的函数。针对几种实验装置得出了结论。
