All-fiber narrow-bandwidth rectangular Optical filter with reconfigurable bandwidth and tunable center wavelength

In this manuscript, a novel narrow-bandwidth rectangular optical filter based on multi-phase-shifted fiber Bragg grating (MPSFBG) is proposed. Using the local temperature control technology, the precise controllable phase shifts are introduced at different positions of the fiber Bragg grating (FBG). Therefore, the bandwidth of the MPSFBG-based filter with good shape factor can be reconfigured from 70 MHz to 1050 MHz by flexibly controlling the numbers and the positions of the phase shifts introduced in the MPSFBG. In addition, the center wavelength of the MPSFBG-based filter can be tuned through controlling the MPSFBG's environment temperature, and the tuning range of 22 GHz is realized. This is one of the best results for the narrow-bandwidth rectangular optical tunable filter with reconfigurable bandwidth. It can be widely used in the processing of reconfigurable signals in the optical communication networks and microwave photonics.