Fiber Sagnac Loop Filter with a Symmetrical Chirped Fiber Bragg Grating
带有对称啁啾光纤光栅的Sagnac环滤波器

The comb filter based on a Sagnac interferometer with a fiber Bragg grating is improved by introducing a symmetrical chirped fiber Bragg grating in the Sagnac loop. The shortages of narrow working bandwidth and unequal passband spacing of the original filter are overcome. Based on designing the parameters properly, a grating with high reflectivity and large reflection bandwidth simultaneously can be realized at a middle refractive index modulation level. Combined with the Sagnac loop, a comb filter with large bandwidth and equal interval can be obtained.