掺稀土离子硅酸盐玻璃2μm发光特性的研究
文献类型：学位论文
| 作者 | 李明 |
| 学位类别 | 博士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 胡丽丽 |
| 关键词 | 2μm发光 稀土离子 硅酸盐玻璃 光谱特性 能量传递 |
| 其他题名 | Spectroscopic properties of 2μm emissions in rare-earth ions doped silicate glass |
| 中文摘要 | 波长在2m的中红外激光，在军事、医疗、环保、遥感监测、光通讯等领域有着非常广阔的应用前景和重要的应用价值。而激光材料又是激光技术发展的基础和核心，很大程度上影响着激光技术的发展。目前国内外对于2μm波段的研究已有大量的报道，其基质主要集中在晶体、石英玻璃、氟化物玻璃和重金属氧化物玻璃中，但对于硅酸盐玻璃的研究还相对较少。 硅酸盐玻璃是由SiO2为主要成分的一种多组分玻璃。由于其玻璃结构的特点，不但保留了石英玻璃光纤良好机械强度、物理化学性能、抗损伤特性等优点，同时具有一般多组分玻璃组分可调范围大、稀土离子溶解度较高等优点，此外原料成本很低，特别是便于和传统石英光纤熔接这一特点，是其它多组分玻璃所不能企及的，是一种理想的适合于稀土离子掺杂的激光材料。因此，本论文的研究目的是探索适合于2μm波段发光的稀土离子掺杂硅酸盐玻璃，从而为未来2μm光纤激光的应用提供一定的理论基础和实验基础。 本论文主要包括六章，其中前两章分别是文献综述和实验方法及理论基础，中间第三至五章是论文的核心部分，第六章为结论。 论文第一章为文献综述部分，首先概述了稀土发光材料的特点与应用，介绍了稀土离子2μm发光机理及玻璃基质材料的研究进展，硅酸盐玻璃的特点及研究进展，进而提出本文的研究内容以及研究思路。 论文第二章为实验方法、测试方法和理论计算部分，主要介绍硅酸盐玻璃的制备方法、物理化学性质测试、结构测试分析及光谱理论计算和分析方法等。 论文的第三章以ED2激光玻璃组分为基础，改变碱金属和碱土金属化合物的种类和相对含量，制备了一系列的硅酸盐玻璃，研究了热学性能。获得了Tg大于550℃，温度参量ΔT和kgl大于250℃和0.3的抗析晶性能良好的多组分硅酸盐玻璃，玻璃的折射率约为1.55。以SiO2-Al2O3-CaO-Na2O-K2O玻璃作为基质，系统地研究了不同浓度Tm2O3掺杂硅酸盐玻璃的热学性能、光谱特性和能量传递特性。利用Judd-Ofelt理论和Forster-Dexter 理论，计算得出三个Judd-Ofelt强度参数和微观能量传递系数。实验结果表明Tm2O3掺杂的最佳浓度为0.75mol%。Tm3+离子的3F4→3H6跃迁的受激发射截面为3.62×10-21cm2，品质因数σemi×τrad为28.48 ×10-21cm2×ms，增益性能良好。通过对荧光衰减曲线分析拟合得到3F4能级的寿命，计算得到无辐射跃迁几率高达2598.3s-1，量子效率仅为4.64%。分析产生较大无辐射跃迁几率的主要原因，一方面由于OH基团荧光淬灭作用，另一方面由于多声子弛豫作用。计算得出0.75mol% Tm2O3掺杂的硅酸盐玻璃中Tm3+离子之间交叉弛豫能量传递系数为6.55×10-40cm6/s。 第四章是在第三章对Tm3+离子单掺硅酸盐玻璃研究基础上，进行了Er3+/Tm3+离子双掺、Yb3+/Tm3+离子双掺、Yb3+/Ho3+离子双掺和Tm3+/Ho3+离子双掺硅酸盐玻璃在结构特性、热学性能、光学特性和能量传递过程等方面的分析。首先在以SiO2-Al2O3-MO-(R2O+2RF)(R=Li, Na, K; M=Ca, Ba)玻璃作为基质的Er3+/Tm3+离子双掺硅酸盐玻璃研究中发现：氟化物的加入尽管会使得玻璃热学性能有所下降，但玻璃的最大声子能量和玻璃基质中的OH基团含量得到了有效地降低。在800nm LD和980nm LD泵浦条件下，观察到了1.86µm的发光，分析了稀土离子之间能量转移机理。测量了Er3+:4I13/2能级的荧光衰减曲线，并计算了Er3+:4I13/2能级到Tm3+:3F4能级的能量转移效率。利用Forster-Dexter 理论计算得到在制备的多组分硅酸盐玻璃和掺氟化物的多组分硅酸盐玻璃中Er3+离子到Tm3+离子的微观能量传递系数分别为8.61×10-40cm6/s和13.39×10-40cm6/s。其次，在以SiO2-AlF3-CaO-R2O(R=Li, Na, K)玻璃作为基质的Yb3+/Tm3+离子双掺和Yb3+/Ho3+离子双掺硅酸盐玻璃研究中发现：Yb3+离子引入极大提高了980nm的泵浦效率。实验表明Yb3+/Tm3+和Yb3+/Ho3+离子双掺能够分别有效地增强Tm3+离子在1.86μm 和Ho3+离子在2.0μm处的荧光。Yb3+:2F7/2→2F5/2能级跃迁在974nm处的吸收截面约为0.8×10-20cm2。通过荧光衰减曲线计算了Yb3+:2F5/2能级到Tm3+:3H5能级的能量转移效率大于95%，到Ho3+:5I6能级的能量转移效率也在75%以上。Yb3+:2F5/2能级到Tm3+:3H5能级和Ho3+:5I6能级的微观能量传递系数分别为1.81×10-4cm6/s和2.2×10-40cm6/s。最后，以SiO2-Al2O3-La2O3-MO-R2O(M=Ca, Ba; R=Li, Na, K)玻璃样品作为基质的Tm3+/Ho3+离子双掺硅酸盐玻璃研究中发现：Tm3+离子对Ho3+离子敏化作用同样明显，在808nm LD泵浦下，0.75mol% Tm2O3/0.4mol% Ho2O3双掺玻璃样品在2.0μm处发光最强，该样品中Ho3+离子的5I7→5I8跃迁的受激发射截面为3.07×10-21cm2。探讨了Tm3+离子和Ho3+离子的能量转移机理，计算得到Tm3+离子到Ho3+离子的能量传递过程(Tm3+:3F4→Ho3+:5I7)需零个(88.2%)或一个(11.8%)声子参与辅助，能量传递系数为15.5×10-40cm6/s，并且当声子能量为320cm-1时，Tm3+离子和Ho3+离子间的能量传递几率最大。此外，还利用两种方式计算了该玻璃中Tm3+:3F4能级到Ho3+:5I7能级能量转移效率，计算所得的能量转移效率大于60%。 第五章是在第四章对稀土离子双掺硅酸盐玻璃研究基础上，进行了Er3+/Tm3+/Ho3+离子三掺和Yb3+/Tm3+/Ho3+离子三掺硅酸盐玻璃在发光特性以及能量传递特性等方面的分析。首先在以SiO2-Al2O3-CaO-R2O(R=Li, Na, K)玻璃作为基质的Er3+/Tm3+/Ho3+离子三掺硅酸盐玻璃研究中发现：利用Er3+离子和Tm3+离子共同敏化Ho3+离子，在808nm LD激发下，获得了比Tm3+/Ho3+离子双掺更强的2μm发光。通过荧光光谱研究发现Er3+/Tm3+/Ho3+离子三掺方式下最佳的浓度配比为1mol%，1mol%和0.5mol%。分析了该系统稀土离子三掺方式下的能量转移过程。随后以SiO2-AlF3-CaO-R2O(R=Li, Na, K)玻璃样品作为基质的Yb3+/Tm3+/Ho3+离子三掺硅酸盐玻璃在发光特性以及能量传递特性等方面的研究中发现：通过普通商用980nm LD泵浦，获得了比Yb3+/ Ho3+离子双掺更强的2μm荧光。分析了该系统稀土离子三掺方式下的能量转移过程。Yb3+离子在硅酸盐玻璃中可以有效地敏化Tm3+离子和Ho3+离子，其能量传递效率可达96.5%。计算得到的Yb3+→Tm3+，Ho3+和Tm3+→Ho3+的微观传递系数都较大，这表明在制备的Er3+/Tm3+/Ho3+离子三掺硅酸盐玻璃中可以较为有效地实现能量传递过程，有利于最终实现2μm发光。 最后是本论文的结论部分，总结了全文的实验结果，同时指出本研究存在的不足和需要进一步研究之处。 |
| 英文摘要 | 2μm lasers have drawn considerable attention due to their wide applications, such as military, surgery, medical treatment, environmental protection, remote sensing, optical communication, and so on. Laser materials are the basis and core of laser technology, and the development of laser technology are significantly affected by laser materials. Up to now, there are many reports about rare earth ions doped materials for 2μm emissions and lasers, such as crystal, silica glass, fluoride glass, heavy-metal-oxide (HMO) glass. However, there are few spectroscopic investigations of the 2 μm emissions in rare earth ions doped silicate glasses. Silicate glass means multi-component glass with SiO2 as glass network former. In contrast to silica glass, silicate glasses are capable of dissolving a much higher concentration of rare-earth ions. Relatively stable physical and chemical properties, low thermal expansion coefficient, higher thermal stock resistance and better compatibility with silica fiber make silicate glass more suitable compared to other multi-component glasses. Thus, silicate glasses can be selected as rare earth ions doped laser materials. The motivation of this study is to investigate rare earth ions doped silicate glass that is suitable for 2μm laser materials and to provide theoretical basis and experimental evidence for 2μm fiber lasers. This dissertation includes the following six chapters. The first two chapters are literature review, experimental methods and theoretical basis. The III, IV and V chapters are the core part of the dissertation. Chapter VI is the conclusion. In Chapter I, the characteristics and applications of rare earth luminescent materials are summarized firstly. After that, the classes and transitions of rare earth ions are introduced. And the research progresses on 2μm laser and emissions in rare-earth ions doped glasses have been reviewed. Thirdly, the characteristics and development of silicate glasses have been presented. Finally, the purpose and research content of the dissertation are proposed. In Chapter II, the experimental methods are introduced, including the preparation procedures of silicate glasses, physical and chemical properties measurement, spectroscopic properties measurements and theory analysis. In Chapter III, based on the traditional laser glass ED2, a series of silicate glasses have been prepared by changing the relative concentrations of the type and content of alkaline metal and alkaline earth metal compounds, and the thermal stability is investigated. The transition temperature Tg is above 550℃, and the glass criterion ΔT and kgl are also above 250℃ and 0.3, revealing that the silicate glasses have good forming ability. The refractive index of our present glass is about 1.55. Based on glass composition of SiO2-Al2O3-CaO-Na2O-K2O, thermal stability, spectroscopic property and energy transfer processes of Tm2O3 doped silicate glasses are investigated. Three Judd-Ofelt intensity parameters and energy transfer microparameters have been determined using Judd-Ofelt and Forster-Dexter theory. The results show that the emission intensity of 1.86μm arrives the maximum when the glass doped with 0.75mol% Tm2O3, and the emission cross section of 3F4→3H6 transition is calculated to be 3.62×10-21cm2. The product of the stimulated emission cross-section and the lifetime (σemi×τrad) is 28.48×10-21cm2×ms, indicating that it is a promising material for 2μm laser applications. The decay curves of glass samples of different Tm3+ concentrations are measured. The calculated result shows a large nonradiative transition rate (2598.3s-1) and low quantum efficiency (4.64%). The reason for larger nonradiative transition rate is mainly due to multiphonon relaxation and fluorescence quenching induced by OH group. The energy transfer microscopic parameter of cross relaxation process is 6.55×10-40cm6/s. Based on the result of Chapter III, structure, thermal stability, optical properties and energy transfer processes of Er3+/Tm3+, Yb3+/Tm3+, Yb3+/Ho3+ and Tm3+/Ho3+ co-doped silicate glasses are studied in Chapter IV. At first, the fluorescence properties of 2μm emissions in Er3+/Tm3+ co-doped SiO2-Al2O3-MO-(R2O+2RF) (R=Li, Na, K; M=Ca, Ba) glasses have been investigated under 800nm and 980nm excitation. The results show that the maximum phonon energy and content of OH group can be decreased by introduced fluoride, although thermal stability seems lower. The intense emission spectra of 1.86µm are obtained. The fluorescence dynamics and energy transfer processes between Er3+ and Tm3+ ions in different pumping schemes are reported. After that, the spectroscopic properties and energy transfer processes of Yb3+/Tm3+ and Yb3+/Ho3+ co-doped SiO2-AlF3-CaO-R2O(R=Li, Na, K) glasses are studied. Upon excitation of a conventional 980nm laser diode, 1.86μm and 2.0μm emissions are obtained from Yb3+/Tm3+ and Yb3+/Ho3+ co-doped silicate glasses, respectively. The absorption cross section of 2F7/2→2F5/2 transition at 974nm can reach as high as 0.8×10−20cm2. Based on the lifetime decay curves, the energy transfers efficiency of the Yb3+:2F5/2 level to the Tm3+:3H5 level can reach more than 95%, and to the Ho3+:5I6 level can also reach more than 75%. The energy transfer microscopic parameters of Yb3+:2F5/2→Tm3+:3H5 and Yb3+:2F5/2→Ho3+:5I6 transition are 1.81×10-40cm6/s and 2.2×10-40cm6/s. Finally, The fluorescence characteristics and energy transfer upon excitation of a conventional 808nm laser diode in Tm3+/Ho3+ co-doped SiO2-Al2O3-La2O3-MO-R2O(M=Ca, Ba; R=Li, Na, K) glasses have been investigated. The results show that the emission intensity of 2μm reaches the maximum when the glass doped with 0.75mol% Tm2O3 and 0.4mol% Ho2O3, and the emission cross section of Ho3+:5I7→5I8 transition is calculated to be 3.07×10−21cm2. The energy transfer processes between Tm3+ and Ho3+ ions are analyzed. The direct transfer of Tm3+:3F4→Ho3+:5I7 is found to be a quasiresonant process with nonphonon 88.2%, having a participation of 1 phonons(11.8%), and the energy transfer microscopic parameter of Tm3+:3F4→Ho3+:5I7 transition is 15.5×10-40cm6/s. Besides, the calculated results show that energy transfer probability reaches the maximum for phonons with energy of about 320cm-1 for Tm3+:3F4→Ho3+:5I7 transition. In addition, energy transfer efficiency of Tm3+:3F4→Ho3+:5I7 transition can be calculated to be more than 60%, estimating in two different ways. Based on the results of Chapter IV, optical properties and energy transfer processes of Er3+/Tm3+/Ho3+ and Yb3+/Tm3+/Ho3+ triply-doped silicate glasses are studied in Chapter V. Firstly, the SiO2-Al2O3-CaO-R2O(R=Li, Na, K) glasses doped with Er2O3, Tm2O3, and Ho2O3 are prepared. More intense 2μm emissions than Tm3+/Ho3+ co-doped glass has been obtained when pumped by 808nm LD. The results show that the emission intensity of 2μm reaches the maximum when the glass doped with 1mol% Er2O3, 1mol% Tm2O3 and 0.5mol% Ho2O3. The energy transfer processes between rare earth ions in this system are analyzed. After that, Yb3+/Tm3+/Ho3+ triply-doped SiO2-AlF3-CaO-R2O(R=Li, Na, K) glasses have been prepared. Upon excitation of a conventional 980nm laser diode, 2μm emissions of Ho3+:5I7→Ho3+:5I8 in Yb3+/Tm3+/Ho3+ triply-doped glasses can be enhanced more effectively than Yb3+/Ho3+ co-doped glass. The energy transfer processes between Yb3+, Tm3+ and Ho3+ ions are investigated. Based on the lifetime decay curves, the energy transfers efficiency from Yb3+ to acceptors can be calculated to be as high as 96.5%. Large energy transfer microscopic parameters of Yb3+→Tm3+, Ho3+ and Tm3+→Ho3+ indicate that sensitizing is an efficient way to improve 2μm emissions. In Chapter VII, all results of present dissertation are concluded. And further work is also mentioned. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15865]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 李明. 掺稀土离子硅酸盐玻璃2μm发光特性的研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
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来源：上海光学精密机械研究所
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