The Synthesis And Spectral Properties Of Rare Earth Ions Doped Mid-infrared Emitting Tellurite And Germanate Glasses

In recent years, mid-infrared lasers become an active issue in the luminescence field due to their wide potential applications in optical communication, medicine, military and environment science. The glass materials exhibit more advantages such as easy preparation, short producing period, and contrable physical properties over the single crystal materials, thus rare earths doped mid-infrared glass materials have attracted increasing attention. In this thesis, Tm3+, Er3+ and Ho3+ doped tellurite, germanate and tellurite-germanate glasses were designed and prepared, and their spectroscopic properties were studied. The new findings we got are list as follows:Tellurite-germanate glasses with composition xGeO2-(80-x)TeO2-9.5ZnF2-10NaF-0.5Ho2O3 (x=0,10,20,30,40,50,60,70,80) were designed and prepared. The Judd-Ofelt parameters were calculated, and it was found thatΩ2 value changes greatly with the TeO2 content, butΩ4 andΩ6 changes lightly. The variation of Judd-Ofelt parameters was assigned to the changes of crystal field felt by the Ho3+ ions. The emission cross sections and optical gain coefficients for 5I7→5I8 transition for different glasses were confirmed, and that the optimum glass system for obtaining laser operation was justed the one containing 20 mol% GeO2 and 60 mol% TeO2.Tm3+ doped 70TeO2-10ZnF2-10Al2O3-10NaF glass was designed and prepared. The basic physical constants such as density, refractive index, ionic number per volume were confirmed. Optical transition intensity parameters were calculated to beΩ2=5.36×10-20 cm2,Ω4=1.33×10-20 cm2,Ω6=0.98×10-20 cm2. The ocscillator strengths, radiative transition rates, branching ratios and radiative lifetime for partial transitions were obtained. Mid-infrared transition properties involving 3H4 level of Tm3+ was analyzed, the emission cross section and absorption cross section between 3H4 and 3H6 levels were derived. The optical gain performance for 3H4→3H6 transition was evaluated.Germanate glass with composition of 75GeO2-20PbO-10BaO-5K2O-0.5Ag2O -0.5Er2O3 was designed and prepared. The metal Ag particles were grown in the samples via an annealing technique by controlling the heating period. Based on the Mie theory, the Ag particle sizes were estimated and it was found that the particle size increases with increasing the heating time first, and then decreases. Fluorescence enhancement was observed in the annealed sample when excited by 488 nm. It was also verified that the fluorescence enhancement is not caused by the local crystal field surrounding Er3+ ions.