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Research On Side-mode Suppression Techniques Of Optoelectronic Oscillator

Posted on:2022-12-21Degree:MasterType:Thesis
Country:ChinaCandidate:Y C SuFull Text:PDF
GTID:2518306764965409Subject:Telecom Technology
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Microwave sources are indispensable components of morden microwave systems.Since it is difficult for a traditional microwave source to achieve a good phase noise performance at the high frequency range,a new type of microwave source based on microwave photonics: Optoelectronic oscillator(OEO),has become a research hotspot.OEO has the ability to generate microwave signals with high frequency and low phase noise,and has great potential for application in fieldes such as communication,measurement,medical treatment,radar et al.But on the other hand,OEO is faced with the contradiction between signal spectrum purity and phase noise.In response to this problem,this thesis starts with a variety of side-mode suppression technologies,aims to construct an OEO which can simultaneously achieve high side-mode suppression ratio and low phase noise through theoretical derivation and experimental verification.The main research contents of this thesis are as follows:1.The system architecture and basic principles of the OEO are systematically introduced.Starting with the open-loop nature of the optoelectronic feedback loop,the threshold condition of OEO is established;the closed-loop properties are studied through the quasi-linearization theory,while the key performance indicators such as power,frequency and phase noise of the oscillation signal in OEO are deduced;and the principles of side-mode suppression schemes based on dual-loop structure and frequencyconversion filtering are deduced in detail,which provides a theoretical basis for building and debugging a high-performance OEO.2.Researches and experimental tests are carried out on three kinds of side-mode suppression technologies of OEO,which are dual-loop structure,injection-locking and frequency-conversion filtering,the threshold conditions and phase noise performance of injection-locking are derived.The side-mode suppression performance and phase noise performance of the above three schemes are experimentally verified and tested,while the advantages and disadvantages of which are studied at length,which provide the theoretical and experimental basis for proposing a novel injection-locked OEO based on frequency-conversion delay matching.3.A novel injection-locked OEO based on frequency-conversion delay matching is proposed and experimentally demonstrated,by which excellent side-mode suppression performance and phase noise performance are obtained.Firstly,the structure and operation mechanism of the proposed OEO are introduced;then,the additional phase noise elimination technology based on frequency-conversion delay matching is theoretically proposed,which provides the theoretical basis for this scheme;finally,the proposed scheme is verified by experiments while its performance is tested.In the experiment,single-tone microwave signals near 10 GHz with high side-mode suppression ratio are generated by the proposed injection-locked OEO when different lengths of fibers are engaged;when a fiber of 3.85 km is employed,a stable single-tone microwave signal at 9.99998 GHz is generated by using the proposed OEO,where the side-mode suppression ratio is measured to be 74.4 dB,which is comparable to that of typical injection-locked OEO engaging identical device;and the phase noise is measured to be-130 dBc/Hz@10 kHz,which is better than that of the typical single-loop OEO engaging identical devices.The experimental results demonstrate the proposed the additional phase noise elimination technology.Consequently,a novel injection-locked OEO which is immunity from the additional phase noise introduced by the externally injected local oscillation(LO)signal is achieved,where excellent side-mode suppression performance and phase noise performance are realized.
Keywords/Search Tags:Optoelectronic Oscillator, Side-mode Suppression Ratio, Phase Noise, Frequency-Conversion Delay Matching
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