Research And Application Of Phase Noise Model Of Optoelectronic Oscillators

Microwave oscillators are the key component of many systems such as communication,measurement,radar and electronic warfare.Phase noise is one of the important indicators to characterize the performance of the oscillators.As a new type of oscillator,the optoelectronic oscillator(OEO)can generate high spectral purity microwave signal up to hundreds of GHz by combining microwave technology and photon technology,which has great research value and application prospects.Scholars from all over the world have carried out in-depth research on the phase noise of OEO,and have made great progress,even so,further studies on the phase noise of OEO are still necessary because the current theories are far from perfect.This thesis mainly studies the phase noise of OEO.Firstly,the research status of common technology and OEO phase noise is introduced.Several typical structures of OEO are summarized and the phase noise characteristics of different structures are compared.At the same time,the existing main theoretical model of OEO phase noise are given and the deficiencies of these models are analyzed.Then the theoretical model of OEO is explained,including its threshold condition,oscillation power,generation mechanism of phase noise and spectrum characteristics.Combined with the above theoretical basis,a comprehensive model for describing phase noise characteristics of OEO is proposed and demonstrated.By introducing the Leeson model,the classical Yao-Maleki model of OEO is modified,and the two typical phase noise distributions corresponding to the Leeson effect in the oscillators using the flicker amplifiers are verified by experiment.Then,the residual phase noise of the device in the OEO is introduced,and the phase domain model of OEO is introduced by deriving the delay link and the phase domain transfer function of the bandpass filter.Finally,considering the influence of fiber disturbance on the phase noise of output signal when the group delay of the filter and the amount of fiber delay can be compared,a comprehensive phase noise model of OEO is established.The phase noise of the near carrier and the far-end of the OEO output signal is accurately given by the comprehensive model,furthermore,it is simple in form and easy to calculate and simulate.Finally,aiming at the contradiction between high Q value and single mode output of OEO,an OEO based on intermediate frequency(IF)filtering is proposed and experimentally demonstrated.Firstly,the working principle of the OEO based on IF filtering is described,and then the transmission relationship of local oscillator(LO)phase noise is given.The simulation results of the phase noise transformation relationship of the LO are given in the case of the IF bandpass filter with non-ideal group delay.Combined with the comprehensive phase noise model of OEO given in Chapter 3,the simulation results of the phase noise of the OEO based on IF filtering is given.Finally,the experiment result shows that the performance of the output oscillation signal is improved by the structure.