Research Of RF Filter Based On Photonic Technology

Microwave photonics is a subject that combines traditional microwave communication technology and traditional photonics which is the two complementary advantages and disadvantages of traditional disciplines,and the scope of its application is wider in recent years.Microwave photonic filter derived from microwave photonics technology has become more and more advanced which uses photonics technology in the domain of RF signal processing and makes up the defects of traditional RF filter that affects filtering performance.Microwave photonic filter has the advantages of high bandwidth and resistance to electromagnetic interference,and its filter response curve has reconfigurable and tunable characteristics which greatly expands its application scope.This thesis mainly focuses on microwave photonic filter with tunable and reconfigurable properties.The main contents are as follows: 1.The main application of the microwave photonics are expounded,and the system structure of RF filter is compared with the microwave photonic filter's structure which leads to their advantages and disadvantages.Then several typical structures of microwave photonic filter are introduced according to the time sequence.2.According to the different standards the microwave photonic filter has been classified,and the basic principles of microwave photonic filter are derived from the digital filter.Then the modulation theory and optical detector are proposed.Lastly this paragraph makes formula derivation and simulation about the optical filter.3.This section introduces the structure of microwave photonic filter which is made up of taps,and the key parameters to affect the filter performance have been analyzed.Then many filter schemes with tunable and reconfigurable characteristics are studied about their system structures and working principle.4.A microwave photonic filter based on the stimulated brillouin scattering is researched.Firstly the scheme uses intensity modulator and optical filter to generate pump.Secondly the stimulated brillouin scattering occurs between pump and phase modulation signal,which completes the conversion from phase modulation to intensity modulation and forms a single passband filter response.Lastly the frequency of the pump is changed by adjusting the frequency of the driving signal,which adjusts the central frequency of the single-pass band.5.A microwave photonic filter based on single side-band modulation is proposed.This scheme uses dual polarization Mach-Zehnder modulator to implement SSB modulation.Then the filter uses the delay line to bring in delay time and changes signal power by adjusting the polarization controller,which forms tunable and reconfigurable properties.This filter tunes the free spectral range by adjusting the delay line,and its response curve can be reconstructed by adjusting the polarization controller.