Tunable multiple-passband microwave photonic filter based on external optical injected Fabry-Pérot laser

This paper proposes a tunable multiple-passband microwave photonic filter (MPF) that is incorporated with an injection-locked Fabry-Pérot (FP) laser. In the proposed MPF, multiple passbands can be easily generated based on the frequency-selection effects of the laser structure in the case of multiple light waves injection. The novelty here is that the obtained multiple-passband MPF can achieve either a dual-passband or a single-passband by using merely one experimental scheme. Moreover, since the laser injection ratio of the proposed scheme is high, the central frequency of each passband has a large tunable range. More tunable passbands can be generated by employing more external wavelengths. By fine-detuning the injection parameters, the frequency tuning range of 17 GHz and the out-of-band rejection ratio of 24.1 dB are achieved for the dual-passband MPF, and the out-of-band rejection ratio of 22 dB and the 3-dB bandwidth of 360 MHz are achieved for the single-passband MPF. In addition, the attained peak power and bandwidth of the proposed MPF are investigated with respect to the injection parameters, including detuning frequency, injection ratio and bias current of FP laser. The stability and dynamic range of the MPF are also evaluated through experiments.