Analysis of Performance Optimization for a Microwave Photonic Filter Based on Stimulated Brillouin Scattering

A single passband microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is analyzed and experimentally demonstrated. The proposed MPF can be tuned over a dramatically large frequency range, which overcomes the disadvantage in previously reported schemes based on SBS that the frequency tuning range is limited within two folds of the Brillouin frequency shift. The single passband MPF is obtained by enhancing the amplitude of the microwave passband generated by SBS gain while suppressing the amplitude of the microwave passband generated by SBS loss through optimizing the key parameters of the SBS process, including the pump power, the length of high nonlinear fiber, and the polarization states of the pump and signal waves. A theoretical model is established to describe the operation principle of the SBS-based MPF and illustrate the mechanism for the single passband, and an experiment is carried out to verify the theoretical analysis. In the experiment, the central frequency of the single passband MPF can be tuned from 0 to 40 GHz, which is only limited by the bandwidth of the adopted electro-optic modulator and photodetector. The main to secondary sidelobe ratio can reach 55 dB and the full width at half-maximum bandwidth is 16 MHz. The achieved MPF is specifically suitable for applications in ultrahigh selective filtering.