Research on Bandwidth-Reconfigurable Microwave Photonic Filter Based On SBS

To solve the limitation that the electrical filter can only process the signal with specific bandwidth in a specific frequency, a frequency tunable and bandwidth reconfigurable microwave photonic filter is proposed. Among them, the filter based on the stimulated Brillouin scattering effect has become one of the research hotspots due to its low threshold, simple implementation and inherent narrow bandwidth. The performance of the filter obtained by the three SBS gain spectrum expansion schemes is compared experimentally. It is proved that the scheme of using a 5-lines comb generated by the external modulator as the Brillouin pump, and controlling its amplitude spectrum shape by a binary phase shift keying vector signal with the code rate of 50 Mbps obtains the best filter performance. A filter with a 3dB bandwidth of 196MHz, a 20dB form factor of 1.31, an in-band ripple of less than 3.5dB, and an out-of-band rejection ratio of more than 20dB is obtained experimentally. Its excellent performance can meet the requirements of hundreds of megahertz filters required by current microwave photonic channelizers. This scheme has low requirements on optical comb performance and Binary Phase-Shift Keying (BPSK) code rate, which has great application prospects.