Preparation And Study Of Highly Yb³⁺-doped Double-clad Phosphate Fiber

The Yb³⁺-doped double-clad fiber has many characteristics,such as the broad absorption and emitting area,high quantum efficiency and so on.The double-clad structure Yb³⁺-doped fiber is used as the gain medium of the fiber laser,which can significantly increase the output power and pulse energy of the laser.It has been widely used in the field of high-power lasers,and has achieved rapid development in the past 20 years.In this paper,the merits and applications of YDCF are summarized,including its working principle and development status in recent years,the highly Yb³⁺-doped double-clad phosphate fiber and the Yb³⁺-doped phosphate polarization-maintaining fiber were successfully prepared,the specific research contents and research results are as follows:1.The highly concentration doped technique has been researched,and the rare earth ion doping concentration of phosphate core glass was improved,the concentration of Yb³⁺in phosphate core glass is more than 5 wt%.2.The problem of phosphate glass water removal has been solved.By analyzing the chemical reaction kinetics process and the effect of hydroxyl group（OH^-）content on performance of phosphate glass in melting process,we have improve the water removal process during the melting and achieve the melting of high quality bulk phosphate glass,the absorption coefficient of OH^-at 2880 cm^-11 has less than 1 cm^-11 in the phosphate glass prepared by the reaction atmosphere method.3.The phosphate glass fiber drawing technology has been studied.Based on the theory of fiber-optic,the optical parameters of glass fiber were designed,And the high-performance phosphate glass fiber is drawn by optimizing the drawing temperature,drawing speed.The core,the inner cladding,and the outer cladding have diameters of 75μm,275μm,and 1.44mm respectively,the core has a numerical aperture of 0.039,the inner clad has a numerical aperture of 0.52;The transmission loss of the double-clad fiber was only 0.07 dB/cm at 1310nm,and the absorption coefficient of 980 nm pump light was 239.5 dB/m.4.Based on the highly Yb³⁺-doped phosphate core glass,the Panda-type polarization maintaining fiber was designed and prepared.The core has a numerical aperture of 0.15 and the core/cladding diameter of 5/125μm.the stress bar size is 31μm,and the distance between the stress zone and the center of the core is 28μm.