Researches Of Yb³⁺ Doped Phosphate Composite Glass Fibers On The Design,Preparation And Performance

1.0?m band amplifiers and lasers using rare earth Yb³⁺doped fiber as the gain medium have extensive and important application requirements in the fields of industry,military,and scientific research.Especially,based on phosphate glass Yb³⁺doped fiber has the advantages of high rare earth ion doping concentration and good spectral performance.It shows great advantages in the generation and power amplification of single-frequency fiber laser with short cavity structure,high repetition frequency mode-locked fiber laser,etc.However,phosphate glass has shortcomings such as easy absorption of water,deliquescent,and instability.If exposed to the air for a long time,it will affect its service life.On the contrary,although silicate glass has a low gain coefficient,it has stable physical and chemical properties and excellent machining performance.In this work,a multicomponent composite glass fiber with rare earth Yb³⁺doped phosphate glass core silicate glass cladding was prepared by using silicate glass as the cladding,which makes up for the shortcomings of the existing phosphate glass fibers.On this basis,the multicomponent composite polarization maintaining fiber was further designed and developed.The specific research contents and research results obtained are as follows:1.The melting process of Yb³⁺doped phosphate glass is studied.In view of the large difference in the softening temperature of the core package,a composite glass fiber with Yb³⁺doped phosphate glass core K9 glass cladding is prepared by the core melting method.The cladding diameter is 124.4?m,the core diameter is 3.8?m,and the transmission loss at 1310nm is 7.56 d B/m,achieving a high gain with a unit length gain factor of 4.2 d B/cm.2.Based on the theory of optical fiber waveguides,a composite glass single mode fiber with a phosphate core silicate cladding is designed.Two kinds of Yb³⁺doped phosphate core silicate glasses are prepared by the Melt in Tube method and the Rod in Tube method respectively.The diffusion of elements of core-clad interface under different drawing processes has been studied.By optimizing the process,the transmission loss of the fiber at1310 nm is reduced to 5.54 d B/m,which provides core gain materials for realizing 1.0?m single frequency laser output.3.The finite element simulation model of the polarization-maintaining fiber is established,and the panda type polarization-maintaining fiber is designed through simulation based on the structure and material parameters of the fiber.By increasing the radius of the stress zone and optimizing the composition of the stress zone to increase the stress birefringence value of the fiber,a high performance Yb³⁺doped multicomponent panda type polarization maintaining fiber is prepared.The diameter of the stress zone is 36.2?m,and the stress birefringence value of the polarization maintaining fiber is 5.1×10^-4,which is 1.5 times of ordinary commercial quartz panda fiber,the fiber has high polarization maintaining performance.