利用可见光测量近红外单模光纤的模场

光纤的模场分布是光纤最基本的特性，它包含了很多光纤的有关信息，单模光纤都工作在不可见的近红外波长范围内，且在可见光范围并非单模工作。提出了一种利用可见光测量近红外单模光纤模场直径的新方法，导出了一个考虑光纤材料色散的更精确地计算不同V值时模场直径的公式，设计了利用可见光直接拍摄模斑的系统，采用缠绕法提取基模，消除了高阶模对测量结果的影响，利用二元非线性曲面拟合，测得了光纤在近红外工作波长下的模场直径。由于无需红外光源、红外探测器以及精密的扫描装置，该方法具有成本低廉、测量速度快、调整容易等优点。

Measurement of Mode Field of Near-Infrared Single-Mode Fibers Using Visible Light

The mode field distribution is the most basic property of optical fibers. It contains much information about optical fibers. But single-mode fibers usually work in near infrared region, and in visible light region these is no single mode. A new method to measure mode field of near-infrared single-mode fibers using visible light is proposed. An accurate formula consid- ering material dispersion to calculate mode field diameter with different V value is derived. A system of measuring mode field diameter using visible light to film mode spot is designed. By using twist method to extract ground mode, the effect of high- er-order mode on the measurement result is eliminated. Mode field diameters of single-mode fibers in near infrared region are measured by using dual element rLon-linear surface fitting method. The system has the advantages of low cost, fast measurement and easy adjusting. As near-infrared light source, near-infrared detector and precision scanning unit are not needed.