With the development of fiber lasers in the direction of higher power, shorter pulse length and higher beam quality, the mode field area of ​​the traditional active double clad fiber becomes the bottleneck of its development. Active optical fiber based on microstructured fiber technology provides an effective way to increase the mode field area. Wuhan Optoelectronics National Laboratory fiber laser technology team Professor Li Jinyan and PhD students Wei Huifeng, who developed a new type of all solid double-clad active fiber, this fiber design with the cladding effective refractive index can be accurately controlled PDC (passively doped cladding technology, which greatly satisfies the requirement of precise control of the refractive index of an ultra-large mode field optical fiber. In this study, it has been demonstrated that a refractive index change down to 1 × 10 -5 can be achieved by adjusting the filling rate of the cladding doping lattice and the concentration of the cladding doping. Experiments using the same preform rod drawn diameter of 50um and 127um optical fiber. Tests show that 50um fiber can achieve stable single mode operation at 1064nm, while 127um fiber mode output can also be achieved with mode optimization. The fiber is an all-solid optical fiber, does not contain any pores, so its drawing process to the simple, and in actual use on the succession, polished surface, the coupler made great convenience. Therefore, this type of fiber is very suitable for high power, high energy fiber laser practical application. This research result is published in the journal OSA Optics Express (Vol. 24, No. 8, pp. 8978-8987, 2016) entitled All-solid very large mode area Ytterbium-doped silica microstructured fiber based on accurate control on cladding index . This research was supported by National Natural Science Foundation of China (No.). PP Corrugated Box Making,Paper Carton Box Making Machine,Kraft Paper Box Making Machine,Die Box Making Machine Jinan Zhuoxing Intelligent Technology Co., Ltd. , https://www.zxtcuttingsystem.com