损耗是多模光纤最重要的指标,精确测量光纤损耗不仅要考虑测量中存在的各种误差,还要考虑模式耦合的影响。本文分析了各种误差对测量结果的影响及其与光纤长度的关系.1.模式误差σ_(?)模式误差与光纤的微分模式损耗(DML)有关,DML 大的光纤模式误差也大。这项误差常被称为暂态误差,它一般只存在于光纤输入端的一段距离内,随着模式分布趋于稳态,这项误差就逐渐消失.但是就一根较长的光纤整 Loss is the most important indicator of multimode fiber. To accurately measure fiber loss, not only the various errors in the measurement, but also the influence of mode coupling should be considered. This paper analyzes the influence of various errors on the measurement results and the relationship between them and the fiber length.Model error σ_ (?) Mode error is related to the differential mode loss (DML) of optical fiber, and the DML large fiber mode error is also large. This error, often referred to as the transient error, is generally only present at a distance from the input of the optical fiber and disappears as the mode distribution tends to steady, but for a longer fiber length