Investigation On 2.0?m Spectroscopic Properties Of Rare Earth Ions Doped Lead Silicate Glasses

With the development of laser technology,optical fiber lasers are very currently attractive and have significantly being investigated due to their some unique advantages including high conversion efficiency,excellent beam quality,less thermal effect,high reliability,compact package and so on.In recent years,fiber lasers mainly focus on Yb³⁺ion doped?1.064?m?,Er³⁺ion doped?1.55?m?,Tm³⁺ion doped and Ho³⁺ion?2.0?m?doped.At present,Yb³⁺-doped fibers emitting in 1.064?m have realized high power and excellent beam quality.Er³⁺-doped fibers emitting in 1.55?m are applied in many photonic devices.However,its peak power is hardly improved for the lack of 2.0?m optical fiber material characterized with high gain and anti-laser damage threshold.Lasers operating in the 2.0?m range have being investigated because of their wide potential advantages,such as good atmospheric transmission characteristic,a strong absorption peak?1.93?m?near water molecules,“eye-safe”for human.They could be used in both military and civilian field including basic scientific research,precision medical laser surgery,environmental monitoring and so on.At present,a great deal of study at home and abroad are focused on single frequency and ultrashort pulse fiber laser of 2.0?m range.Currently,the researches emphasis of glass hosts used to achieve the2.0?m laser are mainly silicate.Silicate is a muli-component glass with SiO₂as the main network former.So it retains robust mechanical resistance and good thermal stability.And In contrast to silica glass,it is capable of hosting relatively great quantities of activator ions.What is more,the cost is cheaper and especially better compatibility with silica fiber make silicate more excellent compared to other muli-component glasses.The motivation of the study is to adjust the compositions of glass for looking for a successful 2.0?m fiber host materials.This paper includes five chapters.The first two are literature review,experimental methods and theoretical basis respectively.III and IV chapter are the core parts.V chapter is the conclusion.Chapter I mainly introduces applications,background and significance of 2.0?m fiber lasers,fundamentals of 2.0?m rare earth ions,research progress of 2.0?m fiber laser matrix,and purpose of this dissertation.Chapter II is experimental methods and theoretical calculation.It mainly includes preparation of glasses,physical and chemical properties measurement,spectroscopic properties measurements and theory analysis.Chapter III is mainly the research of muli-component lead silicate.Samples were prepared by a conventional melting-quenching technology.According to the thermal properties analysis and anti-crystallization test,the glass components were determined.Chapter IV is investigates luminescent properties of Er³⁺/Ho³⁺co-doped?Tm³⁺/Ho³⁺and Er³⁺/Tm³⁺co-doped lead silicate glass and three series of lead silicate glasses are designed and synthesized.1.The study on the enhanced 2.0?m emission intensity of Ho³⁺sensitized by Er³⁺.According to the absorption spectra,Judd-Ofelt theory,Judd-Ofelt parameters,spontaneous transition probability A_radad and radiative lifetime?_rad have been calculated and discussed.The results indicate that efficient 2.0?m emission of Ho³⁺:⁵I₇?⁵I₈ can be obtained.Under 980nm laser diode pumping,the emission can be measured.And when the concentration of Ho₂O₃ increases to 1.5mol%,the luminescence reaches to the maximum value.Energy transfer mechanism between Er³⁺and Ho³⁺is analyzed.The maximum emission cross section of Ho³⁺is 4.2×10^-21cm² around 2.0?m.The gain coefficient reaches 2.1cm^-1 at 2.018?m.These results ensure that the Er³⁺/Ho³⁺co-doped lead silicate glasses can obtain high gain in fiber lasers.2.The study on the enhanced 2.0?m emission intensity of Tm³⁺sensitized by Ho³⁺.According to the Raman spectrum,the largest phonon energy merely reaches to963 cm^-1.Judd-Ofelt parameters and spontaneous transition probability A_radad have been calculated according to Judd-Ofelt theory.Under 808nm laser diode pumping,the emission can be measured.And the luminescence reaches to the maximum value in 1Tm₂O₃/0.3Ho₂O₃ sample.The full width at half maximum of the(Tm³⁺/Ho³⁺)emission amounted to 350 nm in 1Tm₂O₃/0.1Ho₂O₃ sample.Results demonstrated that the prepared Tm³⁺/Ho³⁺co-doped lead silicate glasses have excellent spectroscopic properties On the basis,the energy transfer mechanism were analyzed.3.The study on the enhanced 2.0?m emission intensity of Tm³⁺sensitized by Er³⁺.The Raman spectrum and absorbance spectra of samples were measured.Under808nm laser diode pumping,the optimal luminescence intensity was obtained in the sample with 1Tm₂O₃/2.5Er₂O₃ co-doped.And energy transfer mechanism from Er³⁺to Tm³⁺ion was analyzed.According to the McCumber theory,the calculated maximum emission cross section of Tm³⁺is 2.689×10^-21 cm² at 1863 nm.According to F?rster and Dexter theory,microparameters of energy transfer between Er³⁺and Tm³⁺ions have also been analyzed.It was seen for the case of Er³⁺?Tm³⁺transfer,the back transfer probability is<0.05%of the direct process.Chapter V is the conclusion.Results of present work are concluded in this chapter.And the innovation and shortage of this dissertation are also mentioned.