Single passband, discretely tunable, photonic microwave bandpass filter based on highly birefringent fiber-based comb filter

By experiment, we demonstrate a photonic microwave finite impulse response (FIR) filter scheme that exhibits both the features of flexible frequency tuning and single passband. The proposed filter is constructed by the combined use of a broadband Gaussian-shaped supercontinuum (SC) and a wavelength spacing tunable, highly birefringent (Hi-Bi) fiber-based comb filter. By incorporating a three-segment, Hi-Bi fiber-based, Lyot-type, comb filter into a spectrum slicing-based photonic microwave FIR filter scheme, we achieve both novel features of single passband and passband RF frequency tuning at the same time. It is shown that the discrete tuning of passband RF frequency can be obtained simply by rotating beam polarization. Our experimental demonstration shows a flexible passband RF frequency tuning over a range of 7.3 GHz.