Research Of High Quality Microwave Source Based On Optoelectronic Oscillator

The microwave source is an important component of all electronic systems components.Commercial and military applications for microwave and millimeter-wave sources in aerospace,radar,navigation,communication system require high spectrum purity and low phase-noise oscillators.But especially in the microwave/millimeter wave band,the technologies of conventional microwave source are unable to meet the system requirements.As a novel microwave source,it can generate extremely low phase noise microwave signals.In this paper,a microwave source based optoelectronic oscillator is proposed,which achieves a low phase noise,high side-mode suppression ratio and good stability.In the first,it introduces the research status OEO and compares the advantages and disadvantages of existing programs.Then the basic principles and structure of the optoelectronic oscillator(OEO)is theoretically analyzed,including oscillation threshold,power spectral density and noise performance.Combined with requirements of the subject,we select the dual-loop OEO with different polarization states as a research object,and clarify the principle of side mode suppression,and introduce two phase noise measurement methods for OEO.On this basis,the parameters of laser,photodetector,fiber and other components are analyzed from the perspective of the noise and implementation.Meanwhile,the laser driver and a low-noise amplifier are designed,and the cavity length control module based on phase-locked loop technology is designed to improve the frequency stability.Finally,the OEO prototype is finished and relevant tests are carried out including phase noise,side-mode suppression and stability.In this experiment,the output of a 10 GHz single-mode signal with a side-mode suppression ratio of 70 dB and a phase noise of-140 d Bc/Hz@10 kHz from carrier is obtained.Meanwhile,phase-lock techniques are used to compensate the drift of cavity length.Then the RF stability of the oscillation frequency is measured using a RF spectrum analyzer and the RF stability over 3 hours for the OEO is less than ±4Hz.