Preparation And Properties Of Rare Earth Doped Infrared Germanate Glass

Due to its advantages in atmospheric transmission,biological tissue absorption and eye safety,mid-infrared lasers operating in 2 ?m band has a broad application in military,surgery,communication and remote sensing.Recently,with the development and deepening of the application of optical fiber laser,2 ?m optical fiber laser materials,especially the materials which can be used in high performance laser for fiber laser,is a big attractive work for researchers both at home and abroad.Based on the preparation of germinate glass,the thermal properties and spectroscopic properties were both studied.According to the energy level diagram of Tm³⁺,Ho³⁺and Yb³⁺ ions,energy transfer process among these rare-earth ions and its influencing factors were analyzed in detail.This dissertation includes the following five chapters.The first two chapters are literature review,experimental methods and theoretical basis.The core part of this dissertation is the third and the fourth chapters which introduce the broadband emission of Tm³⁺-doped germanate glass and 2 ?m emission of Ho³⁺-doped germanate glass,respectively.Chapter V is the conclusion.In Chapter I,the research progresses on 2 ?m laser and emission in rare-earth ions doped glass are reviewed.The characteristics of different glass systems and advantages of germanate glass materials are introduced.On the basis of above discussion,the purpose and research content of our work are proposed.In Chapter II,the experimental methods were introduced,including the preparation procedures of germanate glasses,spectroscopic properties measurements and theory analysis.In Chapter III,a series of Tm³⁺-doped germanate glass were investigated in broadband emission.First,the glass formation was studied by the substrate of BaF₂ in GeO₂-Ba OY₂O₃ glass and ?T of 62 GeO₂-16 BaF₂-7Ba O-15Y₂O₃ glass are 290?,respectively.With the introduction of Ga₂O₃,the temperature region of glass fiber drawing is significantly increased while ?T is 298?,respectively.These results shows that the germanate glass is a potential candidate of optical fiber matrix materials.Secondly,the absorption and emission spectra of Tm³⁺-doped germanate glass were tested and analyzed.According to the absorption spectra,the Judd – Ofelt parameters??2,4,6?,the spontaneous transition probability?A?,lifetime??rad?,absorption and emission cross-section??a and ?e?and gain?G?were calculated.While the full width at half maximum?FWHM?was also calculated by emission spectra.The large value of FWHM???= 262 nm?indicates that Tm³⁺-doped germanate glass has good broadband emission at 1.8 ?m,which can beexpected to apply in Tm³⁺-doped fiber amplifier gain medium materials.Thirdly,the Ho³⁺ions were introduced in Tm³⁺-doped germanate glass in order to broaden the emission at1.8 ?m.The emission spectra showed that the addition of Ho³⁺ could significantly increase the fluorescence half-height and width?262 nm to 345 nm?.The energy transfer process between Tm³⁺ and Ho³⁺ ions was discussed based on the absorption spectrum and energy level structure diagram.Finally,the influence of Ga₂O₃ on broadband emission in Tm³⁺-and Tm³⁺/Ho³⁺-doped germanate glass were studied.The increased FWHM?365 nm?shows that the introduction of Ga₂O₃ is beneficial to broadband emission as well as to increase the doping concentration of rare earth ions.In Chapter IV,2 ?m emission were successfully obtained in Ho³⁺,Ho³⁺/Tm³⁺and Ho³⁺/Tm³⁺/Yb³⁺-doped germanate glass.The value of ?2,4,6,A,?rad,?a-?e and G were also calculated and compared.Under the pumping of 790 nm,faint emission spectra can be seen.Combined with absorption spectrum and energy level diagram,it can be ascribe to the unmatched energy level and pumping source.By adding Tm³⁺ions,a strong 2 ?m emission can be obtained?about 160 times?.Combining the absorption spectra and energy level of Ho³⁺/Tm³⁺ions,it is clear that the improved 2 ?m emission due to the strong absorption at790 nm of Tm³⁺ ions and the effective energy transfer process between Tm³⁺ and Ho³⁺ ions.The Yb³⁺ions were introduced in Ho³⁺/Tm³⁺doped germanate glass for the research of 2?m emission under the 980 nm pumping.The 2 ?m emission were increased as much as180 times than Ho³⁺-doped germanate glass and as 13 times than Ho³⁺/Tm³⁺doped germanate glass,which indicates a broadened choice of pumping source.The last Chapter is the conclusion of our work.It also pointed out that something should be improved and done in future.