A reconfigurable microwave photonic filter based on a phase-shifted FBG of two phase shifts

A microwave photonic filter (MPF) with reconfigurable frequency responses using a phase-shifted fiber Bragg grating (PS-FBG) of two phase shifts is proposed and a two-passband filter is experimentally demonstrated with tunable frequency spacing. The PS-FBG with two phase shifts acts as an optical notch filter to suppress one sideband of the phase-modulated signals. Thus, the phase-modulated signals are converted to intensity-modulated single-sideband signals. When the wavelength of the optical carrier from a tunable laser source is tuned into different frequency ranges, the frequency responses of the MPF having two narrow passbands, one passband and one notch, or two notches can be achieved. For the dual-passband MPF, contrasting to a single-passband MPF, the advantages in sensor applications are discussed.