通过改变种子光栅中相邻子光栅的折射率调制量, 提出一种新型交错型采样光纤 Bragg 光栅(ISFBG)设计, 并利用传输矩阵法分析 ISFBG 的反射谱特性。结果表明：对种子光栅中相邻子光栅的折射率设计不同的调制量, ISFBG 的反射谱信道数增加, 主反射峰的反射率主要由折射率调制量大的子光栅决定, 并且其反射率的大小随着折射率调制量差值的增大下降, 次反射峰均匀地分布于每两个主反射峰之间, 其反射率的大小随着折射率调制量差值的增大而增大。同时, 在设计中采用多相移技术可以进一步压缩 ISFG 信道间隔, 增加信道数量。

Based on the index modulation method, an Interleaved Sampled Fiber Bragg Grating (ISFBG) is designed by changing the index modulations of the adjacent sub-gratings in each seeding grating. And the characteristic of reflecting spectrum of ISFBG is analyzed by transfer matrix method. The results show that the number of reflection channels of ISFBG can be tuned for the structure of adjacent sub-gratings with varying index modulations. The reflectivity of main reflection peaks is dependent on the sub-gratings with large index modulations and decreases slightly with the increase of index modulation difference. The secondary reflection peaks are uniformly distributed in the middle of two main reflection peaks and their reflectivity increases with the increment of index modulation difference. Furthermore, the channel spacing of ISFBG can be compressed with channel number increasing by the multiple-phase-shift technique.