基于空间和频谱分辨测量法研究了光纤中的激发模式。利用光纤中激发模式的群时延表达式，理论上推导了基模与高阶模以及高阶模之间的群时延差异导致的光谱干涉公式，进行了相应的模拟计算与分析。对标准通信单模光纤和大模场双包层光纤进行模式测量实验研究，利用单模光纤探针与光谱分析仪扫描探测光谱干涉信号，通过傅里叶变换得到频谱分布，分析得到光纤中激发模式的横向分布和相对功率成分。结果表明，采用空间和频谱分辨测量法可以得到光纤中激发模式的横向分布和相对功率水平，当高阶模相对基模的功率较小时，可以忽略高阶模间的干涉。

A method of measuring excited modes in a fiber based on spatially and spectrally resolved measurement was adopted. According to the expression of the group delay of the fiber modes, the derivation processing of the group delay difference of transverse modes leading to the spectral interference was given as well as the corresponding simulation and analysis. The measurements for a standard communication single-mode fiber and a double-clad large-mode-area fiber were carried out. By using the single-mode fiber and optical spectrum analyzer to measure the spectral interference signal, the spectral interference signal by the Fourier transform was analyzed, and the distributions and power fractions of transverse modes were offered. The results show that the method of measuring the fiber modes based on spatially and spectrally resolved measurement can determine distributions and relative power levels of transverse modes in the fiber. When the high-order modes are weak compared with the fundamental mode, the interference between two different high-order modes can be ignored.