Research On Photonic Microwave Mixing Technologies

Microwave mixer,which can realize frequency up-conversion and down-conversion for microwave signals,is an essential module in electronic systems such as radar,satellite,wireless communications,electronic reconnaissance and countermeasure,deep space exploration systems.In addition,it can also find applications in vector signal modulation and demodulation,spectral analysis,phase noise measurement,automatic phase control and phase-locked loop.Modern electronic systems are developing towards wide operating frequency,large instantaneous bandwidth,high dynamic range and multifunction.Traditional microwave mixing techniques suffer from serious electronic bottleneck including limited bandwidth,inflexible frequency tunability,poor isolation and electromagnetic interference(EMI),and cannot meet the requirements in future electronic systems.Photonic microwave mixer,which mixes microwave signals in the optical domain,features the advantages of large bandwidth,tunable in broadband,high isolation,free from EMI.Furthermore,it is compatible with other photonic signal generation,transmission and processing systems.Due to its good application prospect in future electronic systems,photonic microwave mixing techniques has attracted much interest and research.However,common photonic microwave mixers suffer large conversion loss,limited dynamic range,dispersion-induced power fading after fiber transmission,and so on.To meet the requirements of future electronic systems and solve the technical difficulties existing in photonic microwave mixers,photonic microwave mixing techniques with high conversion gain,large dynamic range,low local oscillator(LO)frequency requirement and suitable for fiber transmission are studied in this dissertation,and the following work is carried out:In Chapter 2,the main performance parameters including conversion gain,noise figure(NF)and spurious free dynamic range(SFDR)is theoretically analyzed,and some reported linearization methods are summarized.In order to optimize the optical carrier to sideband ratio,reduce the NF and suppress the third-order intermodulation distortion(IMD3),a modulation scheme based on a fiber Bragg grating(FBG)and a dispersive fiber,as well as another scheme based on a dual-electrode Mach-Zehnder modulator(DEMZM)and SMF,are proposed and experimentally verified to enhance the system SFDR.In Chapter 3,to supply high-performance microwave local oscillator(LO)signals in microwave mixing systems,photonic generation of low phase noise,frequency tunable microwave LO signals and its application in harmonic mixers is studied.A photonic microwave LO signal sextupling scheme based on cascaded modulators is proposed and experimentally verified.Next,a photonic microwave signal generation scheme with frequency octupling based on a dual-parallel quadrature phase shift keying(DP-QPSK)modulator are proposed and experimentally verified.In addition,the photonic frequency multiplication and mixing technique are combined and a photonic microwave second harmonic mixer based on a DPMZM is proposed and experimentally demonstrated.In Chapter 4,the photonic microwave mixer and the analog photonic link(APL)are combined to realize long-distance transmission of the mixing signals over fiber,and the period power fading induced by the fiber dispersion is studied.A novel double sideband(DSB)modulation scheme based on bi-directional phase modulation in a Sagnac loop is proposed to compensate the dispersion-induced period power fading.Next,a photonic microwave mixing and fiber transmission scheme based on bi-directional use of a DEMZM in a Sagnac loop is proposed,which can simultaneously achieve microwave mixing and fiber transmission without power fading.In addition,a photonic microwave mixer that can realize multi-channel transmission with different fiber length is proposed based on a PDM-MZM,where the power fading in each channel can be compensated by independently controlling the polarization state.In Chapter 5,other applications of photonic microwave mixing technology are investigated.The potential applications of photonic microwave mixing in phase noise measurement,Doppler frequency measurement,direction of arrival,and vector signal modulation and demodulation based on photonic microwave mixing are discussed.A photonic system that can simultaneously perform frequency down-conversion and multi-channel phase shifting for microwave signals is proposed based on a PDM-MZM.Furthermore,using two quadrature down-conversion channels,wideband microwave vector signals with various modulation formats are directly down-converted to in-phase(I)and quadrature(Q)basebands,thus realizing demodulation for vector signals.In conclusion,to meet the development demand of high frequency,large bandwidth,large dynamic range requirements for microwave mixers in future electronic systems,this dissertation is devoted to a systematic study on efficient photonic microwave mixing technologies.Several modulation and mixing schemes are proposed to improve the conversion gain and SFDR;several photonic microwave signal generation schemes with frequency multiplication are proposed to reduce the frequency requirements for microwave LO signals;several modulation and mixing schemes are proposed to compensate the power fading induced by dispersion after fiber transmission;a photonic system that can simultaneously perform wideband microwave signal down-conversion and multi-channel phase shifting is proposed,in which the IQ demodulation of wideband vector signals are realized.