【作者】 刘树江；

【导师】 卢安贤；

【作者基本信息】 中南大学 ， 材料学， 2006， 博士

【摘要】 二极管泵浦固体激光器是近年来国际上发展最快的新型激光器，而作为工作物质的激光材料是研究重点之一。Yb³⁺离子因电子构型简单、理论上不存在交叉驰豫和激发态吸收、吸收峰位于970nm附近能与InGaAs二极管泵浦波长（900～1100nm）有效耦合，非常适合于用作大功率固体激光器的激活粒子。掺Yb³⁺激光玻璃因制备工艺简单、容易形成大尺寸以及可通过调整玻璃组成来优化材料的性能等特点，而成为激光工作介质材料领域的重要发展方向，在现代工业、医学、科学研究和国防军工等各个方面都有着重要应用。由于磷酸盐玻璃具有发射截面大和荧光寿命长等优点，一直以来，磷酸盐系统都是掺Yb³⁺激光玻璃的首选基质材料，但磷酸盐玻璃的结构单元[PO₄]四面体中含有一个P=O双键，致使磷酸盐玻璃呈层状或链状结构，这种特殊的结构决定了其热-力学性能较差，限制了它在各方面的应用。本文以掺Yb³⁺磷酸盐、氟磷酸盐和硼磷酸盐三大体系激光玻璃材料为研究对象，采用传统熔融冷却方法制备了三大体系的激光玻璃材料，利用IR、Raman、X-ray衍射分析、吸收和发射光谱等手段系统研究了三大体系激光玻璃的组成-结构-性能三者之间的相关性，探索了Al₂O₃、B₂O₃、ZnO和氟化物等组分对激光玻璃结构和性能的影响，发现了碱金属和碱土金属离子与掺Yb³⁺激光玻璃热-力学性能和光谱性能之间的变化规律，提出了B₂O₃-P₂O₅-ZnO系统玻璃的定量结构模型，综合比较了三大类激光玻璃材料理化性能的差异，获得了综合理化性能与QX／Yb和FP可比的新型激光玻璃材料。主要研究结果如下：1)在P₂O₅-Al₂O₃-（Nb₂O₅+La₂O₃+B₂O₃）-K₂O-BaO-Yb₂O₃系统磷酸盐玻璃中，引入Al₂O₃有助于改善玻璃热-力学性能，Al₂O₃的含量为7mol％时，玻璃有最好的热-力学性能。随Al₂O₃含量从7mol％到13mol％，非线性折射率n₂逐渐降低，而增益系数σ_emi·τ_m逐渐增大。2)在P₂O5-Al₂O₃-（Nb₂O₅+La₂O₃+B₂O₃）-R₂O／MO-Yb₂O₃（R为Li、Na和K，而M为Mg、Ca、Sr、Ba和Zn）系统玻璃中，随阳离子的场强Z／r²增大，玻璃的热-力学性能按K⁺＜Na⁺＜Li⁺和Ba²⁺＜Sr²＜Ca²⁺＜Zn²⁺＜Mg²⁺的顺序变好，玻璃的光谱性能则随阳离子场强Z／r²的增大而变差，而场强Z／r²较小的K₂O和BaO玻璃表现出最好的光谱和激光性能。3)在多系统氟磷酸盐玻璃中，随氟化物（LiF和CaF₂）取代修饰体氧化物（Li₂O和BaO），玻璃的热-力学性能逐渐改善，非线性折射率n₂、积分吸收截面∑_abs、发射截面σ_emi和增益系数σ_emi·τ_m逐渐增大；碱金属或碱土金属氟化物种类和含量对玻璃的性能也有影响，氟化物阳离子场强Z／r²较大的玻璃具有较好的热-力学性能，与低含量氟化物玻璃相比，氟化物含量较高时的积分吸收截面∑_abs和发射截面σ_emi都明显增大，但氟化物种类对光谱性质的影响不大。4)在P₂O₅-B₂O₃-（Nb₂O₅+Al₂O₃）-（K₂O+BaO）-Yb₂O₃系统玻璃中，当B／（B+P）值超过0.33时将会失透。而在B₂O₃-P₂O₅-ZnO系统玻璃中，由于Zn²⁺在硼磷酸盐玻璃中特殊的配位结构，玻璃的形成范围大大增加，B／（B+P）值超过0.4时仍未失透。另外，由xB₂O₃-（60-x）P₂O₅-40ZnO（x=5，10，15，20和25mol％）系统玻璃的定量结构模型可知，当x≤20mol％时，由于B₂O₃中的B³⁺优先形成[BO₄]，使玻璃的三维网络结构得到加强，ZnO充当网络修饰体进入网络空隙，对玻璃网络结构有断网作用：当x＞20mol％时，由于带负电荷的[BO₄]之间不能直接相连，过量的B³⁺以[BO₃]三角体形式存在，而Zn²⁺以[ZnO₆]八面体形式填充在网络间隙。5)在硼磷酸盐玻璃中，由于P-O-B（4）键的形成，大大提高了玻璃的热-力学性能，甚至与硅酸盐玻璃的相当。由于硼磷酸盐玻璃中存在多种结构单元（如[BO₃]、[BO₄]和[PO₄]等），Yb³⁺离子周围配位场变得复杂，在xB₂O₃-（60-x）P₂O₅-40ZNO玻璃中，随X值增大，积分吸收截面∑_abs逐渐增大，但发射截面σ_emi在x=15mol％时有极大值0.816pm²，因此这时玻璃具有最大的增益系数σ_emi·τ_m。6)通过对三个系统激光玻璃性能的比较，按磷酸盐＜氟磷酸盐＜硼磷酸盐顺序，玻璃的热-力学性能逐渐改善，非线性折射率n₂按磷酸盐＞氟磷酸盐＞硼磷酸盐的顺序降低，三种玻璃中氟磷酸盐玻璃具有最大的积分吸收截面∑_abs、发射截面σ_emi和增益系数σ_emi·τ_m。与国外的QX／Yb和FP激光玻璃相比，氟磷酸盐玻璃Ⅲ-2样品和硼磷盐玻璃BPZ3样品的综合性能优于FP玻璃的，与QX／Yb玻璃相近，有望用于二极管抽运固体激光器的工作介质。更多还原

【Abstract】 The diode Pump Solid State Laser is a new kind of fast developinglaser. In order to meet the requirement of the solid state laser, the researchof laser metatials as working media of the laser has become a majoraspect. Because the configuration of Yb³⁺ ions is very simple withoutcross relaxation and excited state absorption in the theory and theemission spectrum of Yb³⁺ions with main absorption peak around 970nm can be coupled effectively with the wavelength （900～1100nm）pumped by InGaAs laser diode（LD）, it is very suitable to be used asexciting particle in the laser materials for using as high-power laser.Recently, Yb³⁺ doped laser glass have been attrcting increasing attentionbecause of its many advantages such as simple preparation technology,easy to form large size and optimizable properties by adjustingcomposition of glass, and have widely been applied in modern industry,medicine, scientific research and military affairs. As having largeemission cross-section and long fluorescence lifetime, the phosphateglasses have been using as major host materials doped-Yb³⁺. However,there is a double bond P=O in the structural unit [PO₄], which results inthe formation of the chain or layer-like structure in the phosphate glass. Itis very clear that the glass with this kind of structure has poorthermo-mechanical property and less practical application.In this article, Yb³⁺ doped phosphate, fluorophosphate andborophophate system laser glasses have been prepared by means ofconventional melt quenching technology. Correlation among composition,structure and properties of three system glasses were investigated byusing of IR, Raman, X-ray diffraction, absorption and emission spectra.The effect of addition of Al₂O₃, B₂O₃ and fluoride on structure andproperties of the phosphate glass was explored, and the change regularitybetween the thermal-mechanical/spectroscopic properties and thealkali/alkaline oxides was found. The structural model of B₂O₃-P₂O₅-ZnOsystem glass was put forward on the basis of the quantitative analysis ofthe glass structure. The properties of three system laser glasses weresystematically compared. It was easy to know that the prepared laser glasses possess the same excellent comprehensive properties as Qx/Yb orFP glass. The main research results were as follows:1) The thermo-mechanical properties of P₂O₅-Al₂O₃-（Nb₂O₅+La₂O₃+B₂O₃）-K₂O-BaO-Yb₂O₃ glasses can be improved by theintroducting appropriate content Ai₂O₃ and the optimum value of Al₂O₃ isabout 7mol％. The nonlinear refractive index n₂ decreases but the gaincoefficient increases with increasing Al₂O₃ content from 7mol％to13mol％.2) In P₂O₅-Al₂O₃-（Nb₃O₅+La₂O₃+B₃O₃）-R₂O/MO-Yb₂O₃ systemglasses （R for Li, Na and K, M for Mg、Ca、Sr、Ba and Zn）, with increaseof cation field strength Z/r², the thermo-mechanical properties becomebetter in the order of K⁺＜Na⁺＜Li⁺ and Ba²⁺＜Sr²⁺＜Ca²⁺＜Zn²⁺＜Mg²⁺,whereas the glasses containing K₂O and BaO with smaller field strengthshow excellent spectroscopic and laser properties.3) In multicomponent fluorophosphate glasses, the thermo-mechanical properties are improved, at the same time, the nonlinearrefractive index n₂, integral absorption cross-section∑_abs, emissioncross-sectionσ_emi and gain coefficientσ_emi·σ_m increase when Li₂O andBaO are substituted by LiF and CaF₂. In addition, the species and thecontent of fluoride also influence the properties of fluorophosphateglasses, the thermo-mechanical properties are better for thefluorophosphate glasses containing alkali/alkaline fluorides with largercation field strength Z/r², and compared with the fluorophosphate glasseswith low fluoride content, the glasses with high fluoride content showlarger integral absorption cross-section∑_abs and emission cross-sectionσ_emi, but the species of fluoride has little influence on the spectroscopicproperties.4) The devitrifing phenomenon will happen in P₂O₅-B₂O₃-（Nb₂O₅+Al₂O₃）-（K₃O+BaO）-Yb₂O₃ system glasses when B/（B+P） valueis larger than 0.33. However, the phenomenon will not happen in theB₃O₃-P₂O₅-ZnO glasses when B/（B+P） value is larger than 0.4, which isdue to introducting ZnO, which broaden the range of formation ofB₂O₃-P₂O₅-ZnO glasses because of the special coodination of Zn²⁺ ions inthe borophosphate glass. In addition, in the xB₂O₃-（60-X）P₃O₅-40ZnO （x=5, 10, 15, 20 and 25 mol％） glass, B³⁺ prefers to form [BO₄] whichstrengthen network structure, whereas Zn²⁺ depolymerizes networkstructure as modifier when x≤20mol％. When B₂O₃ content is larger than20mol％, the redundant B³⁺ ions form [BO₃] because [BO₄] tetrahedrawith negative charge can not link each other, and Zn²⁺ions form [ZnO₆]in the rich B₂O₃.5) Due to the formation of P-O-B（4） bonds in borophosphate glass,the thermo-mechanical properties are improved greatly and almost areequal to those of silicate glasses. There are various structural units such as[BO₃], [BO₄], [PO₄] etc, therefore the site environment around Yb³⁺become complicated, In xB₂O₃-（60-x）P₂O₅-40ZnO glasses, the integralabsorption cross-section∑_abs increases with increase of B₂O₃ content, butthe emission cross-sectionσ_emi has maximum value of 0.816 pm² atx=15mol％, therefore the glass has maximal gain coefficientσ_emi·τ_m.6) It is found that the thermo-mechanical properties become better inthe order of phosphate＜fluorophosphate＜borophosphate glass, wherasthe nonlinear refractive indexes n2 decrease in the order of phosphate＞fluorophosphate＞borophosphate glass. Among the three system glasses,the fluorophosphate glasses have the largest integral absorptioncross-section∑_abs, emission cross-sectionσ_emi and gain coefficientσ_emi·τ_m.Compared with QX/Yb and FP laser glasses, the comprehensiveproperties of the fluorophosphate glassⅢ-2 and the borophosphate glassBPZ3 are superior to FP, and are equal to those of QX/Yb. The two kindsof glass could be used as the promising working media for diode PumpSolid State Laser.更多还原