Novel microwave photonic filter based on a mode-locked fiber laser

A microwave photonic filter based on a structure of an actively mode-locked fiber laser is proposed. The mechanism and relation between the actively mode-locked fiber laser and the proposed microwave photonic filter are theoretically investigated and experimentally demonstrated. A microwave photonic filter with a free spectral range of about 7.1 MHz, a 3-dB bandwidth of about 0.05 MHz (centered around a frequency of 2.5 GHz), and a Q-factor of about 140 is demonstrated. The proposed microwave photonic filter can be tuned easily by adjusting an optical variable delay line in the ring cavity. A good agreement between the measured results and the theoretical estimations is demonstrated.