Investigation And Sensing Application Of Fiber Parameters On Stimulated Brillouin Scattering Fast Light

In this paper,the characteristics of optical and acoustic field of stimulated Brillouin scattering(SBS)are investigated by the full vector finite element method in photonic crystal fibers(PCF),the propagation characteristics of fast light in PCF under different conditions are studied by the coupling effect of optical wave and acoustic wave,and temperature sensing of SBS fast light is discussed.The main contents and achievements are as follows1.The research progress of SBS fast and slow light are introduced systemically,the SBS process in the fiber is theoretically investigated,and the relationship between the Brillouin gain spectrum and the Brillouin absorption spectrum is described.By analyzing the SBS acousto-optic coupling equations and Kramers-Kronig relations,the mechanism of fast and slow light based on SBS under steady state of small signal solution is explained,and the theoretical model of stimulated Brillouin scattering fast light is established.By using the acoustic-optic coupling effect of SBS,the respective relations between the various parameters of the optical fiber and the time advancement of fast light,pulse broadening factor of signal are obtained.2.The fast light for different PCFs is investigated theoretically.The Brillouin frequency shift,Brillouin threshold,time advancement,pulse broadening factor and pulse waveform for different PCF structures and doping conditions are simulated.The simulation results show that air-filling ratio and doping concentrations affect Brillouin threshold and time advancement of fast light.Smaller air-filling ratio and larger doping concentration induce larger Brillouin threshold.When the input pump power keeps constant,with increasing air-filling ratio and decreasing doping concentrations time advancement increases but quality of output signal becomes worse.When air-filling ratio is 0.8 and the doping concentration is 18%,the range of pump power can be tuned from 0.045 mW to 468 mW,and corresponding Brillouin frequency shift is 9.72 GHz,time advancement is 29.7ns.By simulating the characteristics of SBS fast light under different PCFs,the parameters of PCF are optimized to obtain large time advancement.These conclusions provide reference for designing optical buffers.3.By filling liquid in PCF cladding air hole,Brillouin frequency shift,Brillouin threshold,time advancement,pulse broadening factor and waveform of signal vary with temperature are calculated from 20? to 70?,and the curve of the temperature sensitivity varying with the pump power is depicted.A fast light temperature PCF sensor based on SBS by liquid filling is designed.The results show that PCF is insensitive to temperature without filling,but it becomes sensitive after filling.The time advancement of fast light in PCF with smaller air-filling ratio is more sensitive to the variation of temperature.When pump power is 20 mW,the effective length of the fiber is 10 m,air-filling ratio is 0.8,the pump power can be tuned from 0.055 mW to 575 mW at 70?,time advancement is 36.5ns,while the corresponding time advancement is 32.5ns at 20?.Time advancement of fast light can be modified by varying temperature.These conclusions have a practical value for designing SBS fast light temperature sensor.