A bandstop microwave photonic delay-line filter with both tunable stop-band rejection ratio and tunable frequency

A two-tap bandstop microwave photonic delay-line filter with both tunable stop-band rejection ratio and tunable frequency is proposed and experimentally demonstrated. The stop-band rejection ratio is continuously tuned by adjusting the coefficients of the two taps via the tuning of a polarization controller and the center frequency of the stop band is continuously tuned by changing the optical wavelength to change the time delay difference between the two taps. The proposed rejection-tunable bandstop filter is experimentally demonstrated. A stop-band rejection ratio tunable from 0 to 37 dB and a tunable center frequency from 2.5 to 13 GHz is achieved.