介绍了两种对光纤端面进行修饰以扩大模场直径(MFD)的方法(加热扩散法和熔接透镜光纤法)。利用刀片远场扫描法对单模光纤(SMF)、加热扩芯光纤(TECF)与熔接透镜光纤(GIF)这两种修饰后的高斯分布光纤进行了测量比较,验证了其模场直径分别为10.700 μm,13.129 μm和12.717 μm。并针对实际问题作出修正,通过对单模光纤以及上述两种扩束透镜光纤的分析,得到了相当合理的结果。说明这两种端面修饰法确实能起到扩大模场直径同时又不破坏模式分布的作用。并且验证了修正后的刀片法用于测量修饰后的光纤的各参量是非常有利的。

Two methods were introduced to modify the end of fiber and try to get the expanded mode field diameter (MFD) in this work. In the experiments, three kinds of fibers including single-mode fiber (SMF), thermally expanded core fiber (TECF), and graded-index fiber-lenses (GIF) were measured by using knife-edge scanning. Their MFDs were 10.700 μm, 13.129 μm and 12.717 μm respectively. Considering the true situation, a modification to the theory was given, then tested for the three kinds of fibers just refered. The results of their MFDs and distance between beam waist and fiber ends are fairly correct. The conclusion is that the modified fiber has expanded mode-field diameter and Gaussian distribution. The knife-edge scanning method with modification is feasible to measure the MFD of Gaussian beam with modified fiber ends.