A Novel Tunable Microwave Photonic Band-Pass Filter Based on Chirped Fiber Bragg Gratings

A novel continuously tunable microwave photonic filter with both positive and negative coefficients is presented and experimentally demonstrated. In this paper, multi-wavelength optical carriers are generated based on all-optical mixing in an intensity modulator and a phase modulator. The positive and negative coefficients are realized using a phase modulator and two linearly chirped fiber bragg gratings (LCFBGs) to achieve phase-modulation to intensity-modulation conversion. The tunability of the proposed filter is easily realized by changing the wavelengths of the optical carriers, which is have different delays time interference through reflected by two LCFBGs. Based on the proposed architecture, a two-tap microwave photonic filter with a free spectral range(FSR) tunable from 0.808GHz to 10.71GHz and about -32dB notch rejection level is experimentally demonstrated.