Study On Boron Content,Structure And Fiber Performance Of Boron Doped Stress Application Preform For Panda Polarization-maintaining Fiber

At present,panda polarization-maintaining fiber is widely used in coupler,polarizer,polarization controller,fiber filter,fiber laser and amplifier,fiber gyroscope and other devices.In this dissertation,boron content,structure and fiber performance of boron doped stress application preform for panda polarization-maintaining fiber has been studied.The amount of boron in boron-doped stress application preform of polarization-maintaining fiber was simulated and calculated,and the phase change and phase structure of boron-doped stress application preform in the heating process were analyzed.Finally,the influence of boron content distribution of boron-doped stress application preform on the refractive index of stress bars and the performance of panda fiber were studied.In this paper,based on research idea of Quantitative Structure-Property Relationship,parameters of physicochemical properties refractive index and density as well as the structure parameter molar refraction were correlated with the component parameter boron content,the relationship between material structure,composition and property was responsed by a mathematical model to calculate the boron content of boron doped stress application preform.For boron doped stress application preform,molar refraction of B₂O₃ and SiO₂ was calcuated by the experimental results are 10.54613 and 7.37332,respectively.The simulation model and caculated results were verified by experimental data.The relative errors of boron content between calculated values and measured values are within 0.5%.The results show that the precision of simulation model is high enough to meet the industrial production demand for estimating the boron content of boron doped stress application preform.Secondly,based on the change law of endothermic/exothermic and linear expansion rate in the process of thermal analysis and thermal expansion analysis,coordination of boron and silicon were be analyzed to summarize the change law of boron doped stress application perform phase structure in the process of heating.These were verified by fourier infrared spectrum analysis.Results show that with temperature increasing,the boron doped stress application perform will successively undergo phase separation and miscibility,in this process,the content of some groups changes regularly.Such as boron coordination changes from triangular to tetrahedron and finally transited back to triangular,Silicon-Oxygen network clustering result in the content of Si₂O₅^2-layered structure decreased first and then increased.In addition,it is found that different boron contents have little influence on the phase structure of boron-doped stress application preform during the heating process.Finally,the refractive index of the boron-doped stress application preform along with the z-axis and radial distribution and the performance variation of panda polarization-maintaining fiber along the axial direction were studied.Results show that refractive indexes of boron-doped stress application preform are basically the same along the radial distribution,and the refractive indexes of boron-doped stress application preform show rapid growth firstly,then horizontal,and finally slow growth along with the z-axis direction.In addition,beat length and polarization crosstalk of the pulled panda fiber also increase along with the z-axis direction,however,the loss don’t change much along the axis.The nonuniform distribution of boron content for boron-doped stress application preform due to the unidirectional position of gas nozzle in the preparation process of chemical vapor deposition,which result in the refractive index of boron-doped stress application preform periodic change along the axis direction.Furthermore,it also cause the beat-length and polarization crosstalk of panda fiber increase along the axis.