Characterization Of Brillouin Scattering In Step-index Few-mode Fiber

With the development of communication technology,Brillouin scattering distributed sensor has attracted more and more attention,and has been applied in many fields,such as military,medical,aerospace,industrial inspection and so on.However,the limitation of the capacity of single mode fiber optic sensor and the mode crosstalk of multimode fiber limit the development of optical fiber sensor.The distributed Brillouin scattering sensor based on few-mode fiber is expected to improve the deficiency of single mode fiber and multimode fiber sensor.Compared with the single mode fiber,few-mode fiber has a high power and high transmission capacity.Compared with the multimode fiber,few-mode fiber has a few modes and the modes is easy to control.Because of the advantages of low loss,low dispersion and low dispersion,the few-mode fiber has become a hot research topic in recent years.Therefore,the research on the Brillouin scattering characteristics of the few-mode fiber is of great significance to the development of few mode fiber Brillouin scattering sensor.First of all,this paper makes a fully analysis of the research status of Brillouin scattering and Brillouin scattering sensors at home and abroad in recent years.In this paper,The present distributed Brillouin scattering sensing technology has the cross sensitivity problem in the measurement of multi physical quantities.Few-mode fiber optic sensor is expected to eliminate cross sensitivity to solve this problem.In this paper,the Brillouin scattering characteristics of the few mode fiber are studied.Secondly,In this paper,Brillouin scattering characteristics and threshold characteristics of optical fiber are theoretically analyzed.Based on the theory of wave optics,the mechanism of spontaneous Brillouin scattering and stimulated Brillouin scattering in optical fibers is summarized.The Brillouin scattering characteristics are discussed and the mathematical model of Brillouin scattering spectrum and threshold in optical fiber is analyzed.Finally,based on the study of Brillouin scattering characteristics of the few mode fiber,the finite element analysis method is used to simulate the transmission mode ofSI-10 few-mode fiber.According to the transmission characteristics of different modes,different modes of Brillouin scattering spectrum and intermodal spectrum are studied.The calculation method and influence factors of stimulated Brillouin scattering threshold of few-mode fiber are discussed.