在基于布里渊拍频谱功率测量的分布式光纤传感中，提出对多模声波导结构光纤的应变与温度系数进行理论计算的方法。布里渊拍频谱的功率与光纤的有效折射率、杨氏模量、泊松比、声光有效面积等参数有关，这些参数会随光纤中应变和温度改变。通过建立应变和温度与布里渊拍频谱功率之间关系，可在已知光纤的折射率分布的情况下，从理论上推导出多模声波导结构光纤的布里渊拍频功率-应变系数和布里渊拍频功率-温度系数。以大有效面积光纤(LEAF)为例，计算了光纤的应变和温度系数，并与实验测量结果进行比较。结果表明，使用该方法得到的理论计算结果与实验值相吻合，验证了该计算方法的有效性。

A theoretical calculation method is reported for obtaining strain and temperature coefficients of fibers with multimode acoustic waveguide structure in distributed optical fiber sensing based on Brillouin beat spectrum power measurement. The power of the Brillouin beat spectrum relates to the fiber’s effective refractive index, Young’s modulus, Poisson’s ratio and acousto-optic effective area, and these fiber’s parameters change with the strain and temperature in the fiber. When the profile of refractive index for a studied fiber is available, the Brillouin beat power-strain coefficients and Brillouin beat power-temperature coefficients of fibers with multimode acoustic waveguide structure are deduced by establishing the relationship between Brillouin beat power and strain and temperature. The large effective area fiber (LEAF) is taken as an example to calculate the strain and temperature coefficients of the LEAF and the results are compared with experimental measurements. The results show that the theoretical calculated values obtained by using this method are consistent with the experimental values, and thus the effectiveness of the proposed calculation method is verified.