在考虑波导效应、弹光效应等因素后，详细地理论分析了长周期光纤光栅(LPFG)的横向负载传感特性，包括谐振波长漂移及谐振峰分化后的双峰间距与横向负载、光偏振的关系，模拟计算了单模光纤长周期光栅的横向负载传感特性。理论分析和计算结果表明，长周期光纤光栅谐振波长随横向负载的漂移量和方向与光源的偏振方向有关，加载方向偏振光的谐振波长向短波长漂移，加载正交方向偏振光的谐振波长向长波长漂移，后者的漂移量为前者的2倍以上。横向负载产生的双折射使谐振峰分化为两个子峰，两子峰谐振波长及其间距与横向负载成线性关系，可用于横向负载的高灵敏绝对测量。该结论与已有的长周期光纤光栅横向负载实验结果一致。

The sensing characteristics of long-period fiber grating (LPFG) resonance wavelength shift owing to transverse load are theoretically analyzed, by considering influential factors such as strain-optic effect and the change of wave guide structure. The characteristics include the resonant wavelength shift and the interval between two resonant sub-peaks (namely transmission sub-pits) split in LPFG spectrum. According to the analytical properties, the sensitivity coefficients of the resonant wavelength shifts and the sub-peak wavelength interval, which are due to transverse load for a long-period fiber grating in single-mode fiber, are numerically calculated. The simulation results show that the shift directions and sensitivity coefficients of resonant wavelengths are dependent on the polarizations of light source. The resonant wavelength of linear polarization source in the direction of forcing transverse load shifts to shorter wavelength (blue shift), and the resonant wavelength corresponding to the polarization in the orthogonal direction of forcing shifts to longer wavelength (red-shift). The shift ratio of resonant wavelength to longer wavelength is over 2 times larger than that to shorter wavelength. The birefringence caused by transverse load splits the resonant peak (transmission pit) into two resonant sub-peaks in LPFG spectrum. The sub-peak shifts and the interval between two resonant sub-peaks are well linear with the transverse load, which can be used for highly sensitive measurement or absolute measurement of transverse load. These conclusions are in good agreement with the published results of the transverse load experiments.