Fiber Nonlinear Coefficient And SRS Gain Coefficient Measurement And Research

Nonlinear effects can occur when the transmitting signal power is large enough inoptical fibers. The nonlinear effects mainly include Self Phase Modulation (SPM), CrossPhase Modulation (XPM), Stimulated Raman Scattering (SRS)and Stimulated BrillouinScattering (SBS). It’s quite necessary to accurately measure the nonlinear coefficient (γ)not only for experiment research but also optical fiber companies. By analysis of itsdiscipline and influencing factors, we can improve the design of fibers for opticalcommunication or nonlinear effects applications.As for the nonlinear effects, the thesis takes the SRS as our subject of analysis whichcan compensate the transmitting power of signal in long haul optical communication. SRScan offer gain for the optical signal with big gain bandwidth, it can also amplify severalsignals simultaneously in wave division mixing (WDM) optical system. Therefore it’s veryimportant to accurately measure the SRS gain coefficient.Thus the thesis is making measurement and research for the nonlinear coefficient andSRS coefficient for optical fibers (mainly single mode fiber). The main work is listed asfollows:(1) The thesis discusses the physical mechanism and quantum explanation of γ indetails, the measurement methods are introduced. Then the SRS mechanism and explanationare also discussed. The dissertation discusses the transmitting process with formulas.(2) Methods of nonlinear coefficient and SRS gain coefficient measurement we take arerespectively proposed, and the theory of measuring is discussed, including the equipmentfunction and software arithmetic. By using the LabVIEW software environment as tool, wemanaged to control the equipments automatically to get the data needed for calculation.Matlab module is inserted in the LabVIEW software. Then nonlinear coefficient and SRSgain coefficient are auto-measured.(3) Nonlinear coefficient and SRS gain coefficient are measured for different type offibers. The stability and accuracy are both discussed. These two coefficients are given as tothe YOFC fibers，whose results are very close to what has been measured by others. This canoffer some referee for the nonlinear effects applications.