A novel sampled Bragg grating comb filter with a ladder chirped structure

Based on a sampled fiber Bragg grating, a novel approach to obtain high channel-count comb filters is proposed for wavelength-division-multiplexing (WDM) system in this letter. There is a non-continuous linear chirped structure like a ladder in grating period. And refractive index modulation amplitude with Hamming spatial profile is used within the samples. The 26-channel comb filter with channel spacing of 50 GHz is then fabricated, it features in multiple equalized passbands with flat-top steep-edge and high transmittance which will benefit as multi-channel optical add/drop filters in WDM system.