Microwave photonic filters based on phase modulator and Fiber Bragg Gratings

A novel microwave photonic filter is proposed based on phase modulator and Fiber Bragg Gratings in this paper. Using the bipolar properties of the gratings, both a high-Q band-pass filter and a notch filter can be switched by adjusting the attenuators. Numerical simulations demonstrate that the filter performances are influenced by the zero pole position of the transfer function, and then the system simulation results show that a frequency response of a high Q band-pass filter with a Q factor of 114 and a rejection ratio of around 45 dB, and a flat notch frequency response with QN value exceeding 48 are obtained. Furthermore, compared with the filters whose signal powers cannot be separately controlled, the proposed notch filter´s performances is improved through separately controlling signal powers.