2?m Spectroscopic Properties Of Rare Earth Ions Doped Germanate-Tellurite Glasses

Mid-infrared fiber laser operating at ² ?m contains many important characteristic spectral lines.It has extensive applications in medical diagnosis,environmental detection,optical communication and so on.This dissertation mainly investigated the germanate-tellurite glasses for ² ?m applications.According to the compositions optimization of germanatetellurite glasses and the concentration adjustment of rare earth ions,germanate-tellurite glasses were prepared for ² ?m emissions.The main results are as follows:Firstly,the germanate-tellurite glass with good thermal stability and superior anti-crystallization property were prepared.The DSC analyses indicate that the prepared germanate-tellurite glass having a higher T_g?550°C?and no obvious Tx during 300-820°C.To verify the anti-crystallization ability of the prepared glass,the anti-crystallization experiment has been made.The result shows that the prepared germanate-tellurite glass having a good anti-crystallization ability,which suggests that the composition can be used as 2?m mid-infrared emission glass host.2?m emission properties were investigated in various Tm³⁺ concentrations and results indicate that no concentration quenching was observed when Tm³⁺ content was 1.25 mol%.Investigations indicate that cross relaxation?CR?,which is beneficial for population inversion of 2 ?m emissions.The Fourier Transform Infrared?FTIR?transmittance spectrum of prepared sample has been tested to calculate the OH-content.Through Gauss decomposition of the absorption peak of the FTIR,the configurations of OH-in glass have been researched.Moreover,the modified glass with low OH-content has been prepared and energy transfer mechanism between Tm³⁺ and OH-was studied.2?m spectroscopic performances were investigated in Er³⁺/Tm³⁺ codoped and Er³⁺/Tm³⁺/Yb³⁺ triply-doped germanate-tellurite glasses.Judd-Ofelt intensity parameters and radiative properties were calculated and discussed based on absorption spectra and Judd-Ofelt theory.However,with the increasement of Er³⁺,the fluorescence intensity becomes weaker.Energy transfer mechanism between Tm³⁺ and Er³⁺ was quantificationally studied,and it is found that energy from Tm³⁺ to Er³⁺ is larger than Er³⁺ to Tm³⁺,which is unfavourable to 2?m emission.Interestingly,the fluorescence intensity of triple-doped sample becomes stronger than doubly doped sample.At the same time,2?m spectroscopic performances were investigated in Ho³⁺/Tm³⁺ codoped germanate-tellurite glass and Ho³⁺/Yb³⁺ codoped germanate glass.The measured lifetime of Ho³⁺:5I7 level is as high as 6.07 ms in Ho³⁺/Tm³⁺ codoped germanate-tellurite glass and 7.68 ms in Ho³⁺/Yb³⁺ codoped germanate glass,respectively.The energy transfer processes between Ho³⁺ and Yb³⁺ were discussed.On the other hand,to some extent,it is suspected that the decrease of energy from Yb³⁺ ions to Ho³⁺ ions is due to the fluorescence quenching in prepared samples.