Research On Microwave Frequency Multiplication Based On Microwave Photonics

The frequency of microwave signal is required higher and higher in the application of the satellite,radar,electronic warfare and next generation wireless communication.However,the generation of high frequency microwave using traditional electronic technology is extremely hard due to electronic bottleneck.A new method can solve this problem with the development of microwave photonics.It is a new technology to accomplish the processing of microwave signal by optical technique.Compared with traditional electronic technology,microwave photonics has the merits of high bandwidth,low loss,small in size and anti-electromagnetic.The generation of microwave signal in microwave photonics technique has the advantages of multiplication fator and tunable in frequency.In this thesis,the research about frequency multiplication of Local Oscillator(LO)is performed based on external modulation,and the main work are described as following.1.Some common electro-optic modulators are introduced and their structures and working principles are analyzed.In addition,the photodetector is simply illustrated.A simulation analysis for DSB,SSB and OCS-DSB modulation methods is executed using the VPI simulation software.The conclusion about working performance of the electro-optic modulator when two different direction lights through it respectively is stated and verified in experiment.The definitions of the OSSR,RFSSR and phase noise are explained.2.A photonic structure to generate frequency sextupled micorwave signal uisng an IM and a Sagnac loop with another IM imbedded inside in series is proposed and experimetally demonstrated.In the experiment,a 21 d B optical sideband suppressiong radio(OSSR)and a 15.1 radio frequency spurious suppression radio(RFSSR)are observed.Compared with the LO signal,the phase noise of the generated microwave signal deteriorates 15.9 d B,which meets the phase noise deterioration theory.In addition,the proposed system has no optical or electrical filter so that the generated frequency of the system can be tuned flexibly.In the last,the experiment is carried out again while the frequency of LO signal is 6 GHz,7 GHz,8 GHz and 9 GHz respectively,and optical spectra are obtained.3.A simplified filterless frequency octupling scheme based on cascading an intensity modulator(IM)and a dual-parallel Mach-Zehnder modulator(DPMZM)is proposed in this paper.The approach is verified by experiment,and 32 GHz millimeter wave is generated by applying 4 GHz LO signal.A 15 d B radio frequency spurious suppression radio(RFSSR)is acquired and the phase noise of the generated microwave signal is not deteriorated.Compared with other schemes,the scheme is simple in configuration because only an IM and a DPMZM are needed.Besides,the generated signal has high frequency tunability and purity.4.A filterless photonic frequency-octupling scheme is presented in this article.It is implemented by cascading a Sagnac loop with an IM in it and a DPMZM in series.The scheme is an improvement of the above approach and is verified by experiment,and a 32 GHz mm-wave signal is produced with the assistance of a 4 GHz LO signal.A 20 d B optical sideband suppression ratio(OSSR)and a 17 d B radio frequency spurious suppression radio(RFSSR)are realized,and no extra deterioration of phase noise is observed.Besides,the verification of the frequency tunability is implemented in the experiment.5.A novel filterless photonic structure to generate 12-tupling mm-mave signal based on two DPMZMs in series is investigated in this paper.The scheme is verified by using VPI simulation software,and a 60 GHz mm-wave is generated from a 5 GHz signal source.A 23.6 d B optical sideband suppression ratio(OSSR)and a 16.1 d B radio frequency spurious suppression radio(RFSSR)are observed in the simulation.In addition,the performance of the frequency tunability is also analyzed.