高浓度稀土离子氟化物玻璃及四磷酸盐玻璃光谱性质研究
文献类型：学位论文
| 作者 | 张龙 |
| 学位类别 | 博士 |
| 答辩日期 | 2000 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 胡和方 |
| 关键词 | 高浓度掺杂 稀土离子 氟铝酸盐玻璃 四磷酸盐玻璃 光谱性质 微片激光器 |
| 中文摘要 | 固体激光器的小型化、集成化发展趋势以及现代光通信对单纵模激光的需求驱动了微片激光器的发展。为了获得足够的增益，微片激光器的基质材料必须是高浓度离子掺杂。然而高浓度掺杂往往会引起强烈的浓度猝灭，及引起玻璃失透，这是目前影响玻璃基微片激光器发展的两个主要障碍。因此寻求低浓度猝灭的高浓度稀土离子掺杂的玻璃系统是目前发展玻璃基微片激光基质材料的一个重要课题。本文主要围绕高浓度稀土离子掺杂玻璃中的光谱性质，为其在微片激光器中的应用提供条件。本文首先在引言中概括了研究高浓度稀土离子掺杂的氟铝酸盐和四磷酸盐玻璃的目的和意义，接着在文献综述中详细介绍了掺Nd~(3+)、Er~(3+)和Yb~(3+)激光玻璃的研究概况及其最新研究进展，同时概括了LD泵浦的微片激光器的研究进展，在此基础上给出了本文的研究思路。在论文的第二章，介绍了本文的研究方法，详细介绍了实验中样品的制备、测试、及光谱理论计算，包括Judd-Ofelt理论、McCumber理论、倒易法、Fuchbauer-Ladenburger公式等。在论文的第三章，我们研究了稀土离子（Er~(3+), Tm~(3+), Yb~(3+)/Tm~(3+)）, 尤其是高浓度掺杂，在氟铝酸盐玻璃中光谱性质，发现了许多新的现象，提出了许多新的观点。首次发现在高浓度Er~(3+)掺杂氟铝酸盐玻璃1.5μm荧光浓度猝灭效应很小，在12mol-% (2.58*10~(21) ions/cm~3) ErF_3时，荧光强度达到最大值，其最大荧光强度也远比ZBLAN玻璃和磷酸盐玻璃大，因此可以认为Er~(3+)掺杂的AYF玻璃，即使是高浓度掺杂下，团簇效应及协作上转换的作用是很小的，是理想的1.5μm微片激光器基质玻璃材料；在研究了高浓度Er~(3+)掺杂氟铝基玻璃上转换发光后，提出在高浓度Er~(3+)掺杂AlF_3玻璃中，交叉弛豫~4S_(3/2)+~4I_(9/2)→2~4F_(9/2)对红光上转换发射起主要控制作用，致使红光荧光强度I∝（P_(ex)）~(1.6)。首次提出650mm附近泵浦光激发下Tm~(3+)在氟铝酸盐玻璃中转换荧光为两光子步进吸收所致，并在完整的光谱理论计算的基础上，合理推测了476nm上转换红光的发光机制。在本章的最后，较为全面地分析了Yb~(3+)<->Tm~(3+)间的能量传递通道，并以此解释了Yb~(3+)/Tm~(3+)在氟铝酸盐玻璃中的荧光的特性。论文第四章主要研究高浓度稀土离子掺杂四磷酸盐玻璃光谱性质。首先研究了高浓度Yb~(3+)在四磷酸玻璃中光谱性能：对于LiYb_(0.1)La_(0.9)P_4O_(12)玻璃，峰值吸收和发射截面分别为0.99pm~2和1.32pm~2，激发态最小粒子数β_(min)、饱和泵浦强度I_(sat)及最小泵浦强度I_(min)分别为0.1111、17.05kw/cm~2、1.89kw/cm~2，具有与国际上近期开发的Yb~(3+)激光玻璃相当的光谱性能和激光性能参数，且其Yb~(3+)离子掺杂浓度可以很高(Yb_2O_3的含量最高可达12.5-mol%)。在Yb~(3+)掺杂四磷酸盐玻璃中，随着Yb~(3+)浓度增加，峰值吸收截面、积分吸收截面(∑_(abs))、以及主峰值发射截面(σ_(emp))和次峰值发射截面(σ_(ems))、荧光寿命等都下降，有效发射线宽Δλ_(eff)增加；激发态最小粒子数（β_(min)）、饱和泵浦强度(I_(sat))及最小泵浦强度（I_(min)）上升；在1.82*10~(21)/cm~3左右时储能参数(Nσ_(abs) τ_m)和增益参数(Nσ_(abs) σ_(ems) τ_m)达到最大值。发射主峰荧光强基Yb~(3+)浓度为1.22-182*10~(21)ion/cm~3时，出现最大值。比较倒易法和F－L公式计算结果表明，在高浓度Yb~(3+)掺杂情况下，利用倒易法计算Yb~(3+)的离子的发射截面具有较高的可信度，它排除了发光捕获效应的影响，是一种简单有效的方法。接着研究浓度参杂Er~(3+)、Yb~(3+)/Er~(3+)在四磷酸盐玻璃中1.54μm发射特性，研究表明：Er~(3+)离子在四磷酸盐玻璃中1.54μm峰值发射截面σ_e为0.48pm~2 (McCumber理论计算)；Yb~(3+)/Er~(3+)掺杂四磷酸盐玻璃中，从Yb~(3+)到 Er~(3+)有很高的正向能量传递效率η，Yb~(3+)的最佳浓度约为1.82 * 10~(21) ions/cm~3, Er~(3+)最佳浓度约为0.96 * 10~(20) ions/cm~3。同时也研究了在四磷酸盐玻璃中OH基对RE(Yb~(3+) Er~(3+))近中红外发光的影响，描述RE到OH的能量传递速率议程（W_(OH)=K_(OH)N_(RE)α_(OH),）计算了Yb~(3+)、Er~(3+)离子与OH间朴素作用的强度参数K＿（OH），在四磷酸盐玻璃中它们分别为9.1 * 10~(-19) cm~4S~(-1)。本文第五章在研究Nd~(3+)掺杂四磷酸盐玻璃光谱性质的基础上，进行了其微片激光器实验，得到连续的1.05μm激光输出。最后是本论文的结论部分，概括总结了全文的实验研究结果，同时指出了存在的不足及需补充改进之处。 |
| 英文摘要 | Research upon microchip laser is mainly driven by the demand for single-frequency lasers and compactness of solid lasers. For microchip lasers, the RE concentration in the host glasses must be as high as possible to ensure sufficient gain despite short active length. However, the appearance of concentration quenching and devitrification at high RE concentrations in most glass systems has been the major obstacle in this area. In this thesis, the work is focused upon spectroscopic properties of highly RE doped glasses, and their prospected application in microchip lasers was also evaluated. The purpose and significance on investigation of spectroscopic properties in the highly-RE-doped fluoroaluminate (AYF) glass and tetraphosphate glass are stressed in the Introduction. Following as the lists of laser theory foundation on RE doped materials, the new development of laser glasses in Chapter One, and the new development of LD pumped microchip lasers, the idea of this dissertation is presented. In Second Chapter the experiment methods are introduced, including the preparation procedures, spectroscopic property measurements, and spectroscopic calculation using Judd-Ofelt theory, McCumber theory, reciprocity, and Fuchbauer-Ladenburger equation. In Chapter Three, the spectroscopic properties in RE ions doped, especially highly doped, fluoroaluminate glass were investigated. Some new results have been found, and some new ideas were presented. Firstly, the effect of concentration quenching to 1.5μm-fluorescence in the highly Er~(3+) doped glasses was found to be very small. The optimum Er~(3+) concentration for 1.5μm emission is around 12mol-% (i.e. 2.58 * 10~(21) ions/cm~3), and the fluorescence intensity in fluoroaluminate glass is also much larger than that in ZBLAN and tetraphosphate glass. It can be inferred that even in high Er~(3+) dopant, the effects of clusters and cooperative upconversion in Er~(3+): AYF glass are very small. Secondly, based on upconversion results in Er~(3+): AYF glass upconversion red is inferred to be mainly controlled by the cross relaxation, ~4S_(3/2)+~4I_(9/2) →2~4F_(9/2), which causes the intensity of upconversion red I∝(P_(ex))~(1.6), where P_(ex) is exciting power. Thirdly, using excitation spectra in Tm~(3+)-doped AYF glasses, we predicted that the excitation mechanism of the upconversion fluorescence is likely ESA process (not energy transfer). In addition to ESA, the new mechanism of 476nm-upconversion fluorescence was also assumed. In Chapter Four, we investigated the spectroscopic properties of highly RE doped tetraphosphate glasses. In first Section, the parameters of spectroscopic and laser properties was completely calculated. In LiYb_(0.1)La_(0.9)P_4O_(12) glass, the measured lifetime, absorption cross-section and excitation cross-section at their peaks, are 1.21 ms, 0.99pm~2 and 1.32pm~2, respectively, and β_(min), I_(sat), I_(min) are 0.1111, 17.05kw/cm~2, 1.89kw/cm~2, respectively, which is comparable to the laser glasses developed abroad recently. The concentration effect of spectroscopic properties and laser performance parameters were also investigated in this Section. Comparison between results calculated from reciprocity method and F-L equation show that the reciprocity method without effect of fluorescence trapping is more confident in high dopant than F-L equation with effect fluorescence trapping. In Section 2, Er~(3+) and Yb~(3+)/Er~(3+) doped tetraphosphate were investigated for application of microchip laser at 1.5μm. The emission cross-section σ_(ex) was calculated using McCumber theory, and is 0.48pm~2 at 1.54μm. The high energy transfer efficiencies (η) of Yb~(3+)→Er~(3+) were found in Yb~(3+)/Er~(3+) doped tetraphosphate glasses. The optimum doping concentrations in LiEr_x yB_yLa_(1-x-y)P_4O_(12) are obtained, 1.82 * 10~(21) ions/cm~3 Yb~(3+) and 0.96 * 10~(20) ions/cm~3 Er~(3+). The effect of OH~- on near IR emissions in RE doped tetraphosphate glasses was also investigated, and the rate of energy transfer from RE→OH~- can be expresses, W_(OH)= K_(OH)N_(RE)α_(OH), here N_(RE) is RE concentration, α_(OH) is absorption coefficient, K_(OH) is a constant determined by the force of interactions between RE ions and OH groups. The values of K_(OH) for Yb~(3+) and Er~(3+) are 9 * 10~(-19) cm~4s~(-1) and 15 * 10~(-19) cm~4s~(-1), respectively. In Chapter 5, following the investigation of spectroscopic properties of Nd~(3+) doped tetraphosphate glasses, a room-temperature LiNd_(0.1)La_(0.9)P_4O_(12) microchip laser operating at 1.054μ m pumped by an AlGaAs diode laser operating at 800nm has been realized. Finally, all results of present work are outlined, and it is suggested that something should be done in the next stage. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15390]  |
| 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 | 张龙. 高浓度稀土离子氟化物玻璃及四磷酸盐玻璃光谱性质研究[D]. 中国科学院上海光学精密机械研究所. 2000. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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