Research On The Structure And Optical Properties Of Rare Earth Doped Germanosilicate Glasses

Laser operating in the 2³?m wavelengths is widely used in the fields of infrared remote sensing,laser ranging,fiber communication,bio medical and so on,due to its strong penetrating ability,eye-safe and many other advantages.Germanosilicate glasses possess high potential in mid-infrared optical applications because of lower phonon energy,high solubility,good glass forming properties,high thermal stability et.al..It has recently attracted considerable interest of many scholars.Firstly,this thesis reviewed the rare earth ions luminescence mechanism theories,the development of 2.0?m fiber laser and the applications of germanosilicate glasses.On this basis,Ho³⁺and Tm³⁺ions doped germanosilicate glasses and glass-ceramics cotaining fluoride crystallines were prepared by traditional melt quenching method.Infrared spectroscopy,thermal analysis,absorption spectra and fluorescence spectroscopy were used to study the effects of glass compositions and rare-earth doping concentrations on the glass structure and optical properties.Finally,2.0?m fluorescence from rare-earth ions in germanosilicate glasses enhanced by changing the heat treatments.The main results were as follows.Tm³⁺ions doped germanosilicate glasses were prepared by melting method.Effects of doping concentrations of Tm³⁺ions and GeO₂ contents on the glass structure and luminescent properties were investigated.There were not only[SiO₄]tetrahedron and[GeO₄]tetrahedron in the germanosilicate glasses,but also[SiO₄]&[GeO₄]polyhedrons in the network frame of germanosilicate glasses.The luminescence intensity and quenching concentration of Tm³⁺ions varied when changing the contents of GeO₂.When the glass sample with 20mol%GeO₂ and 1mol%Tm₂O₃,the sample has the strongest fluorescence intensity.The lifetime of ³F₄ level from Tm³⁺increased apparently with GeO₂ content increased.1.8?m luminescence originating from Tm³⁺:³F₄?³H₆ was obtained by ET processes from Yb³⁺ions to Tm³⁺ions upon 980nm LD Intense,and the fluorescence intensity increased when Yb³⁺-concentration increased.Ho³⁺ions doped germanosilicate glasses were prepared by melting method.The results showed that the 2.0?m fluorescence intensity was the strongest when the content of GeO₂ was 20mol%,the lifetime of ⁵I₇ level gradually increased as the content of GeO₂ increased.And when Ho³⁺ ions doping concentration increased,the fluorescence intensity increased apparently.2.0?m luminescence originating from Ho³⁺:⁵I₇?⁵I₈ was obtained through ET processes from Tm³⁺ions to Ho³⁺ions upon 790nm excitation,and the fluorescence intensity increased sharply when the concentration of Tm³⁺ions increased.Tm³⁺/Ho³⁺co-doped glasses were with much stronger 2.0?m fluorescence intensity than Ho³⁺doped glasses because of the ET processes from Tm³⁺ions to Ho³⁺ions.We also investigated the fluorescence properties in Ho³⁺/Yb³⁺co-doped germanosilicate glasses under 980nm excitation.2.0?m emission was realized in Ho³⁺/Yb³⁺co-doped glass through ET processes from Yb³⁺ions to Ho³⁺ions,and the fluorescence intensity increased when Yb₂O₃ doping concentration increased.Ho³⁺/Tm³⁺co-doped30SiO₂-20GeO₂-15Al₂O₃-5B₂O₃-30BaF₂?mol%?glass-ceramics containing fluoride crystallines were prepared.Ba₃AlF₉ crystals were precipitated in the glass-ceramics with the heat treatment at 620?/8h,the sample had the strongest 2.0?m fluorescence emission.In addition,the fluorescence spectra showed that the luminescence properties of germanosilicate glass could be optimized largely through appropriate heat treatment.