The Investigation Of Spectral Properties Of Er³⁺/Yb³⁺ Co-doped Fluoride Phosphate Glass And Fiber

Ultrashort pulse fiber laser plays an important role in filed physics, biochemistry,materals, precision machining due to its simple structure, small size and the highenergy conversion efficiency. At present the ultrashort pulse laser medium ofYb³⁺-doped phosphate and silicate glass has many shortcomings, such as sharp gainlines, wide pulse width, and low output power of ultrashort pulse. Therefore, it isworth of exploring a new gain medium which is suitable for high-power ultrashortpulse laser.Many reports have shown that fluorophosphate glass is a promising host materialfor ultral short fiber lasers due to its wide fluorescence bandwidth and low nonlinearcoefficient. The aim of this thesis is to study the spectroscopic and crystallizationproperties of Er³⁺/Yb³⁺co-doped multi-component fluoride phosphate glasses in orderto use a conventional fabrication method to develop glass fiber, which can be used forultrashort pulse fiber laser.In this thesis, we systematically investigated the fluorescence spectra, glassstructure and the crystallization property in the Er³⁺/Yb³⁺co-doped fluoride phosphateglass based on the fluorine-oxygen ratio and the variation of glass composition, andthe relationship of these properties was concluded. With the increase of phosphateconcentration in the glasses such as FP5, FP15, FP20, the fluorescence lifetime ofEr³⁺ion at1.5μm has become longer while the545nm fluorescence lifetime has gotshorter, and the glass crystallization trend is getting smaller which is helpful for fiberfabrication. We also found that the Er³⁺ion at1.5μm has much flatter optical gainproperty in the fluorophosphate than that in the phosphate glass. Therefore, highphosphate containg glass （FP20） was chosen for further optimizing study. Based onFP20, glass composition was optimized with the thermal analysis and fiber drawingexperiments by changing the content of the glass network modifier （LiF） and networkformer （Al （PO₃）₃）. The results show that the glass containg LiF of18mol%and Al（PO3）3of20mol%has the most thermal stability and excellent fiber drawing property.Energy transfer between different rare earth ions of Ce³⁺/Er³⁺/Yb³⁺was studied, and the optimized concentration ratio was determined to be Ce³⁺: Er³⁺: Yb³⁺=1:1:2in thefluorophosphates glass.Finally, the core and cladding glass compositions of fluorophosphate glass weredecided, and large bulk of highly homogeneous laser glass without gas bubbles wasfabricated by the optimized melting process. Rod-in-tube technique was employed tomanufacture the optical fiber, and the1.5μm fluorescence was observed in the fiberunder980nm LD pump.