基于耦合模理论,采用传输矩阵法分析了相移对级联长周期光纤光栅传输特性的影响.研究表明,当级联光栅间相移量从0至π变化时,传输谱主阻带左边会出现一个小的阻带,且相移量越大,小阻带的幅值越大.当相移量增大到π时,小阻带幅值增大到与原阻带相当；当相移量从π增至2π时,传输谱主阻带右边会出现一个小的阻带,且相移量越大,小阻带的幅值越小.随相移量的增大,主阻带最大损耗峰对应的谐振波长向长波长方向偏移.调节相移量可灵活地改变主阻带最大损耗峰对应的谐振波长,为新型光纤光栅器件的开发提供新的视角和理论依据.%Effect of phase shift on transmission characteristics of cascaded long-period fiber gratings is analyzed using transfer matrix methods based on coupled-mode theory. When the phase shift changed from 0 to ir,a little stop band appeared on the left of the main stop band. The greater the amount of phase shift, the bigger the amplitude of the small stop band. When phase shift increases to π , amplitude of small stop band is equal to that of the original stop band. When the phase shift changes from π to 2π , a little stop band appeared on the right of the main stop band. The greater the amount of phase shift,the smaller the amplitude of the small stop band. With the increase of the phase shift,the peak of the resonance wavelength of the main stop band shifts to the long wavelength direction. The resonant wavelength can be flexibly changed by adjusting phase shift. The research provides theoretical foundation for the development of new fiber grating devices.
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