Tunable and reconfigurable microwave photonic filter based on Fourier domain optical processor and cascaded fiber rings

A tunable and reconfigurable microwave photonic filter (MPF) based on a Fourier domain optical processor (FD-OP) and cascaded fiber rings is proposed and demonstrated. A stable and multiple wavelengths source can be realized by using a broadband source and a waveshaper. The multiple wavelengths source with different wavelength spacings is achieved by programming the waveshaper. Two fiber rings of the same structure are cascaded together to achieve a high main sidelobe suppression ratio (MSSR) and a high Q factor. The FD-OP is induced to add additional phase shifts to achieve tunability. When the number of taps is 60, by introducing cascaded two-fiber rings and the FD-OP, the MSSR is 59.356 dB, the maximum Q factor is 470.895 and the 3dB bandwidth of the filter is 0.019 GHz. The simulating results show that the center frequency continuously tuned from 4.47-13.41 GHz. The tunability and reconfigurability of the MPF are well realized.