Sensing And Compensation For The Inter-Modal Dispersion And Via Stimulated Brillouin Scattering In Optical Fibers

In this paper,the acoustic characteristics of stimulated Brillouin scattering,and the interaction between optical and acoustic are investigated in optical fibers by the full vector finite element method and backward differentitaion method,the potential applications of stimulated Brillouin scattering are exploited for the inter-modal dispersion compensation and sensing.The main results are as follows:1.A novel design scheme of simultaneously temperature and strain sensing via guided acoustic-wave Brillouin scattering is proposed for resolving the cross sensitivity induced by temperature and strain in single mode fibers.In guided acoustic-wave Brillouin scattering which occurs due to interaction between two optical co-propagating wave and the transverse acoustic wave in optical fiber,multi spectrum peaks appear when the frequencies of pump and Stokes are matched.Then the temperature and strain can be calculated by the different impact of temperature and strain on each acoustic mode.The simulation results indicate that the temperature sensitivity of R02 mode is 0.86% lower than TR25 in the SMF-28 fiber,but the strain sensitivity of R02 mode is 54.1% higher than TR25.Temperature sensitivity of R02 is approximately equal to that of TR25,but strain sensitivity of R02 is obviously diferent from that of TR25.So the influence of temperature and strain on Brillouin frequency shifts can be effectively distinguished,thereby simultaneous measurement of temperature and strain can be realized by guided acoustic-wave Brillouin scattering.2.The inter-modal dispersion and the time delay in stimulated Brillouin scattering in few mode fibers are studied by using the backward differentitaion method.The inter-modal dispersion is compensated via stimulated Brillouin scattering.The simulation results admit that LP11 shows exactly equivalent time delay to inter-modal dispersion in the designed experimental setup.In addition,compensation mechanism exhibits outstanding applicability and excellent matching performance to a wide range of inter-modal dispersion caused by different Stokes,outside interference,irregularity of fiber and so on.This design has the advantages of high flexibility,wide range of applications and certain practical value in optical fiber telecommunication networks.