Fabrication And Investagation On Characterization Of Ytterbium Doped Silica Glass And Photonic Crystal Fiber

High concentration Yb-doped photonic crystal fibers （PCFs） with large mode area areconsidered as ideal medium for lasers and have been widespread concerned by researchersin this field. Presently, conventional chemical vapor deposition （CVD） method is still themain for the Yb-doped fibers preparing being used. Due to the unavoidable defects ofCVD, such as low concentration, uneven refractive index distribution, difficulty infabricating large core fibers, a non-chemical vapor deposition method was presented forsolving the problems. Based on the theory and experiments, the dissertation focused on thekey issues existed in the preparation of Yb-doped silica glasses and a variety of highconcentration Yb-doped photonic crystal fibers with large mode area were designed andfabricated. The main research works were as follows:（1）Summarized the research progress of optical fiber lasers and the fabrication ofdoped fiber in the world, analyzed the existing problems and proposed effective methodsfor solving those problems.（2）High concentration doped mixed material was prepared by Non-CVD method. Ahigh concentration Yb-doped silica glass was prepared with Plasma furnaces and hightemperature graphite furnace, and for investigating the influence of preparing process onspectra characteristics, optical properties were characterized, such as absorption propertiesand fluorescence characteristics.（3）Due to the strong oxidization of Yb³⁺, there exist chemical valence changeproblems in preparation progress, researches on the formation conditions and opticalcharacteristics of Yb²⁺were carried out under different preparation process, includingabsorption characteristics under near-infrared and visible waves, stimulated emissioncharacteristics under ultraviolet and visible waves. In addition, the applications of Yb²⁺inwhite light sources areas were also investigated.（4）Based on the applications of large mode area fibers and birefringence fibers inhigh power optical fiber lasers areas, researches on the theories and designs of large modearea photonic crystal fibers, single-mode single-polarization PCFs, high birefringence octagonal PCFs and tapered birefringence PCFs were carried out. Yb-doped PCFs weredrawn out and the optical characteristics were analyzed including propagationcharacteristics, fluorescence characteristics, researches of photoluminescence andsuper-continuum.