High Channel-Count Ultra-Narrow Comb-Filter Based on a Triply Sampled Fiber Bragg Grating

Based on a sampled fiber Bragg grating (FBG) with simultaneous utilization of two amplitude-assisted phase sampling functions and a phase-only sampling (POS) function, a novel comb filter that has a high channel count and an excellent channel uniformity is first proposed. With the proposed method, an ultra-narrow FBG-based filter with consecutive 1377 channels, a channel bandwidth of 1.5 GHz, and a channel spacing of 25 GHz is theoretically demonstrated.