High channel-count comb filter based on sampled fiber bragg grating

Optical frequency comb is of an important interest for all-optical signal processing and microwave photonics. In this study, a PZT-induced phase shift occurred in a linearly chirped 51-channel FBG is experimentally demonstrated. This induced phase shift is fairly stable and the magnitude of the induced phase shift can be controlled. As an important application of this multichannel filter, an ultra-narrow comb-filter is proposed and experimentally demonstrated. Moreover, Based on a sampled fiber Bragg grating (FBG) with simultaneous utilization of two amplitude-assisted phase sampling (AAPS) functions and a phase-only sampling (POS) function, a comb filter with excellent channel uniformity is firstly proposed. As an example, an ultra-narrow FBG with consecutive 1377 channels enabling to cover whole band of (O+E+S+C+L+U) is numerically demonstrated, which has a channel-bandwidth of 1.5 GHz and channel spacing of 25 GHz.