设计了具有双峰滤波特性的相移光栅及取样光栅, 利用传输矩阵方法对其滤波特性进行了研究。结果表明, 多π相移光栅及π相移取样光栅均可获得双峰滤波特性, 并且π相移取样光栅比多π相移光栅具有更好的双峰滤波特性, 其反射频谱的旁峰幅度比多π相移光栅低得多。调整π相移取样光栅的占空比(取样长度与取样周期的比值)位于0.66～0.8范围内时, 得到了更好的双峰滤波特性, 特别是占空比为0.75时其旁峰反射率整体上处于最低值。

Phase-shifted fiber Bragg grating and sampled fiber Bragg grating with dual wavelength filtering properties are designed and their properties with transmission matrix method are studied. As a result, both multi- π phase-shifted grating and π phase-shifted sampled grating have dual wavelength reflective profile. Moreover, the side lobe of reflective profile of π phase-shifted sampled grating is lower than that of multi- π phase-shifted grating. By adjusting the duty cycle of π phase-shifted sampled grating in the range of 0.66～0.8, better dual wavelength filtering profile is obtained, especially the side lobe reflective index is lowest when the duty cycle is 0.75.