|
With the development of the information technology, Microwave photonics have been defined as the study in microwave or photonic system. Because of the advantages such as low cost, wireless connection in microwave system, and low loss, wide bandwidth, immunity to electromagnetic interference(EMI) in photonic system, microwave photonic filters(MPF) have attracted much attention.Microwave photonic filters are periodic in spectrum since they sample the input signal at a time rate given by T based the fiber delay lines(FDLs). Thus, the spectral period or FSR is given by 1/T. Single-bandpass MPFs have been proposed to overcome this limitation.In this study, microwave photonic filters (MPF) based on the cascaded High-Birefringence (Hi-Bi) fibers is developed. Combined with MZ-EOM and SMF, the base-band response is eliminated, bandpass response is obtained. In different cascading conditions, the state expression of n-cascaded 2n taps is obtained, and the relationship between the Hi-Bi fiber length, SMF length, bandpass frequency, -3dB Bandwidth, Q value of the MPF is demonstrated. Adjustable rang of band-pass response is 8~25GHz, Q value is 39, good reconfigurability and high side-lobe suppression ratio are obtained. Finally, based in the single-loop FDL, double-loops or mutil-loops FDLs have been constructed in theory.
|