Theoretical And Experimental Research On The Characteristics And Applications Of Vector Stimulated Brillouin Scattering

Stimulated Brillouin scattering(SBS)is one of major nonlinear effects in optical fiber,which has wide applications in the fields of optical fiber sensing and microwave photonic signal processing based on the vector characteristics of energy transfer and phase change.The characteristics of vector SBS are very important for design and implementation of the application systems based on vector SBS,but no comprehensive research has been done.In order to make adequate and flexible use of vector SBS characteristics,it is strongly requested to clarify its properties.Therefore,the theoretical and experimental research on the characteristics and applications of vector SBS has been done comprehensively,the main research contents and achievements are presented as follows:1.The key techniques for performance optimization of Brillouin optical time domain analysis(BOTDA)system based on SBS have been theoretically analyzed and experimentally researched.The polarization characteristic of BOTDA system has been theoretically analyzed,and the reduction of system polarization noise and the improvement of measurement accuracy of Brillouin frequency shift through polarization scrambler have been experimentally demonstrated.The power characteristic of BOTDA system has been theoretically and experimentally analyzed,and the optimization strategy of the system is obtained.The multi-wavelength BOTDA system has been theoretically analyzed,and the improvements of system signal to noise ratio and measurement accuracy of Brillouin frequency shift have been experimentally demonstrated.The improvement of system signal to noise ratio and the optimization of system performance by introducing self-heterodyne detection scheme and selecting the polarization scrambler position have been experimentally demonstrated.2.The characteristics of vector SBS have been theoretically analyzed and experimentally researched.The mathematical model of vector SBS is established and the experiment system based on heterodyne pump-probe technique is designed.The pump wave power,fiber interaction length and spectrum width of light source linear dependencies of vector SBS response spectrum have been obtained by theoretically analyzing and experimentally measuring.The influence of probe wave on vector SBS response spectrum has been studied.The influences of dispersion and nonlinear effect in the fiber on vector SBS phase shift spectrum have been analyzed.The power thresholds of double-end-injected gain and loss SBS have been measured by an experiment system based on pump-probe technique.The power threshold definition of gain SBS based on the inflection point method and the power threshold definition of loss SBS based on the minimum method in wide power range have been proposed.The influence of probe wave on double-end-injected based vector SBS threshold has been studied.The influences of SBS power thresholds in two double-end-injected mechanism on vector SBS response spectrum have been compared.The research on characteristics of vector SBS provides the theoretical basis for the application based on vector SBS.3.A temperature or strain measurement technique based on loss vector SBS phase shift spectrum for Brillouin optical fiber sensing system has been proposed.The fiber temperature and strain have been measured,respectively.The Brillouin frequency shifts obtained from the measured SBS phase shift spectrum and amplitude spectrum are almost the same,and both have shown a linear relationship with temperature and strain,respectively.A high accuracy temperature or strain measurement technique based on double-sideband vector SBS phase shift spectrum for Brillouin optical fiber sensing system has been proposed.The fiber temp erature and strain have been measured,respectively.The Brillouin frequency shift obtained by the proposed technique has shown a linear relationship with temperature and strain,respectively.The temperature and strain measurement accuracy in the proposed system have been improved by one time compared with that in single-sideband system.A fast and wide range temperature or strain measurement technique has been proposed and the wide range temperature has been measured quickly.4.A pulse pre-pump Rayleigh BOTDA sensing technique based on the signal shaping in time domain and spectral domain has been proposed.The pulse pre-pump Rayleigh BOTDA sensing system has been designed and the mathematical model of step pulse wave has been established.The mathematica l models of pulse pre-pump Rayleigh BOTDA system by using the transient analysis of steady state SBS coupled waves equation and perturbation analysis of transient SBS coupled waves equation have been established.