Theoretical And Experimental Research On Microwave Photonic Filter Based On Multi-wavelength Optical Source

Microwave Photonics is a new interdiscipline course which combines microwave signal process with optics method. As an important direction of Microwave photonics,MPF(microwave photonic filter) overcomes the electronic bottleneck of traditional filters and works in optical domain. So MPF simplifies structure to a great extent. In addition to tunability and reconfigurability, MPF has advantages of large bandwidth, low loss and immunity to electromagnetic interference. This paper studies incoherent MPF based on multi-wavelength fiber laser with theoretical analysis and experiment demonstration. The main contents and innovation points are shown as below:(1)The fundamental principle and application of Microwave Photonics and MPF are discussed. The MPF is classified by different characteristics. Recent MPF research status and MPF based on multi-wavelength fiber laser are summarized.(2)Basic principle and structure of tunable MPF are given. Two kinds of comb filter in fiber laser(Mach-Zehnder interferometer and Sagnac interferometer) are studied by theoretical analysis and numerical simulation.(3)A tunable and reconfigurable MPF based on multi-wavelength fiber laser and MZ interferometer is proposed. The tunable characteristic is based on slope filter of MZ interferometer. Lasing power of different wavelength is changed by period of MZ spectrum’s change to achieve variable tap coefficient. Lyot-Sagnac filter is added to fiber laser to get adjustable wavelength spacing, thus center frequency of passband can be tuned and passband shape can be reconfigured.(4)A MPF based on multi-wavelength fiber laser and CFBG is proposed. The FSR of MPF is raised by CFBG’s feature. The MPF has a invariable MSSR. Various output of fiber laser is realized by spectrum shaping, corresponding parameters of MPF are analysed.(5) MPF experiments are demonstrated. The moving of passband center frequency caused by different lengths of dispersive fiber is discussed. Two different kinds of multi-wavelength fiber laser are realized with corresponding filter response. Tunable and Reconfigurable RF response is achieved by adjusting the lasing output.