Design And Preparation Of YB Doped Double-Clad Photonic Crystal Fiber For High-Power Fiber Lasers

In the field of the high power fiber laser, the rapid development of high power photonic crystal fiber laser become a new bright spot. Compared to ordinary traditional fiber, the design of microstructure fiber structure is flexibility. This optical fiber can achieve different fiber characteristics, such as the infinite single-mode, large mode area, cladding numerical aperture and controllable non-linear effects by improving its structural parameters. And it combines with the technology of double-clad pump and rare-earth doping, which can prepare Yb³⁺-doped double-clad photonic crystal fiber and build high-power photonic crystal fiber laser, to obtain output of high-power, high-quality, high-energy continuous laser beam. This paper has two main parts, one part is the numerical analysis and design of Yb³⁺-doped double-clad photonic crystal fiber, the other part is the preparation of double-clad Yb³⁺-doped photonic crystal fiber preparation,Firstly, the normalized frequency, numerical aperture, the effective mode area, nonlinear effects and confinement loss of the photonic crystal fiber are numerical simulated and analyzed by multi-pole method. And the effective mode and confinement loss in different layers of air hole and different structure of cladding are numerical compared. The theoretical reference of designing a photonic crystal fiber is determined by the relationship between the value of p (thus the ratio of air hole diameter to air hole pitch) and various parameters. And the structure of Yb³⁺-doped double-clad photonic crystal fiber which is suitable for high power fiber lasers is designed by this reference.Secondly, the composition of high melting point Yb³⁺-doped laser glass materials is detemined by the early experimental studies. After several tests, the ideal Yb³⁺-doped laser glass is obtained through solution doping the powder, plasma melting the laser glass and polishing. Yb³⁺-doped photonic crystal fiber for the preparation is ready.Finally, the capillary which is the prepared Yb³⁺-doped laser glass are periodic arranged around the core, which made performs. And Yb³⁺-doped double-clad photonic crystal fiber is prepared by drawing tower.