Laser Performance Of Yb-Doped Aluminosilicate Binary Glass Fiber

With the advancement of technology,fiber lasers are widely used in medical surgery,military security and other fields due to a series of advantages,such as high power,high brightness,high efficiency and so on.They have become a representative of a new generation of lasers.Yb-doped fiber laser has great potential in high power output.As the core gain medium,Yb-doped special fiber directly affects the output performance of high power fiber lasers.In this paper,Yb-doped aluminosilicate binary glass fiber as the observation object was fabricated by chelate gas phase doping technology.We have analyzed the material characteristics and laser performance of Yb-doped aluminosilicate binary glass fiber,respectively.The microstructure was calculated by theoretical method and compared with the experimental results to provide theoretical explanation for the material characteristics of the fiber.The results that were comprehensively analyzed provide comparative data in order to optimize the Yb-doped fiber preparation formula and manufacturing process.Critical issues for improvement suggestions were provided in this paper.The main contents of this thesis are as follows:(1)The double-clad ytterbium-doped aluminosilicate fiber was prepared by chelate gas-phase doping method.The theoretical calculation was introduced,that is,the fused quartz model was obtained by using molecular dynamics to simulate the quenching process.Based on the first principle of density functional theory,the structure of the model was optimized.(2)Combination with theory and experiment,the material characteristics of Yb-AlSi binary glass fiber was studied.In the experiment,the fiber was subjected to testing material characteristics,such as cross-section element distribution,refractive index distribution,and absorption spectroscopy.The results show that the element doping concentration and refractive index distribution are homogeneous in the core,but the absorption capacity is relatively weak.In the theoretical calculation,the Yb-AlSi cluster model was constructed and the properties are calculated.It is confirmed that the Yb ion has a valence of+3 in the fiber and the absorption wavelength is around 976 nm.At the same time,the feasibility of theoretical calculations is also illustrated.(3)The Yb-doped aluminosilicate binary glass fiber laser testing platform was independently established in order to study the laser performance.It mainly includes the slope efficiency,laser spectrum,beam quality,output laser stability.The results show that the output laser spectrum is very pure.There is no nonlinear effect.And the output power does not decrease significantly during the long-term stability evaluation of the highest power.However,the output efficiency is low and the beam quality is degradation at high power,indicating that mode competition occurs in the fiber.It is not conducive to high-power laser output.