High channel-count comb filter based on chirped sampled fiber Bragg grating and phase shift

Based on strongly chirped sampled fiber Bragg grating and phase shifts, a novel approach to obtain high channel-count comb filters is proposed in this letter. Various channel spacing can be achieved by a single strongly chirped phase mask where the required phase shifts can be gained by a precise translation stage. Comb filters with channel spacing of 50, 100, and 200 GHz are then designed with the same phase mask. Experimentally, a 35-channel 100-GHz channel-spacing comb filter is fabricated, from which one can expect that high-performance comb filter with various channel spacing can be fabricated by conventional technology.