光学碱度对稀土离子掺杂锗酸盐玻璃荧光特性的影响研究

【作者】 王荣飞；

【导师】 邱建备；

【作者基本信息】 昆明理工大学 ， 材料学， 2014， 博士

【摘要】 稀土元素由于其独特的电子层结构具有上转换、下转换、近红外发光性质而被广泛的应用于全固态激光器、立体显示、光纤放大器用增益材料等发光材料中,稀土离子掺杂材料的各种应用都需要较高的发光效率作为基础,稀土离子的发光效率与其所处基质光学碱度环境相关,基质光学碱度对稀土离子电子在各能级的布居、能量传递有较大影响。稀土离子的发光性质可通过光学碱度调控。本文研究了光学碱度对稀土掺杂玻璃发光性质的影响。研究了碱金属、碱土金属锗酸盐基质玻璃的结构。随着碱金属/碱土金属离子半径的增加,对Ge-O-Ge键削弱增加,形成的非桥氧键增多,引入的富于氧原子,锗氧四面体[GeO4]向锗氧[GeO6]八面体转变。在不同激发波长激发下,基质玻璃的折射率随加入的碱/碱土金属离子半径增大而增加。研究了光学碱度对Er3+掺杂碱金属/碱土金属锗酸盐玻璃的上转换发光性质的影响。通过改变碱/碱土金属离子种类及离子浓度,调控基质玻璃的光学碱度。研究结果表明,随着碱/碱土金属离子半径及离子浓度的增加,基质光学碱度增加。在980nm激光激发下,随着光学碱度增加,红绿上转换的Hi1/2， S3/2， F9/2能级粒子布居数降低,Er3+掺杂碱金属/碱土金属锗酸盐玻璃的红绿上转换的发光强度降低。另一方面,光学碱度增加,玻璃基质共价性降低,Er3+离子受周围环境的束缚降低,Er3+离子之间的距离增大,能量传递效率降低,导致红色上转换发光强度降低更为明显。研究了光学碱度对Er3+、Tm3+、Bi离子单掺杂锗酸盐玻璃的近红外发光性质的影响。通过改变碱/碱土金属离子半径及离子浓度,调控玻璃基质的光学碱度。研究结果表明,在980nm激光激发下,随光学碱度增加,晶体场参数Ω6降低,吸收和发射截面积减小,4I13/2能级的寿命降低,半高宽减小,Er3+掺杂锗酸盐玻璃在1.55μm处出现近红外发光随着光学碱度的增加而降低。在808nm激光激发下,Tm3+掺杂玻璃的近红外发光强度随光学碱度的增加而降低,半高宽减小。对Bi离子单掺杂锗酸盐玻璃的近红外发光研究结果表明,玻璃基质的光学碱度改变,Bi离子的红外超宽带发光强度、荧光带宽以及荧光寿命等都随之发生变化,在690nm激光激发下,半高宽最宽可达428nm。通过调控玻璃基质的光学碱度,实现对Bi离子发光强度及半高宽的调控。本研究成果将对今后超宽带光放大材料领域的研究工作提供一定的理论基础。研究了不同泵浦源下,光学碱度对Bi/Yb3+离子共掺杂锗酸盐玻璃近红外宽带发光性质的影响。研究结果表明,Bi/Yb3+离子间的相互能量传递机制随着光学碱度的变化而改变,随着光学碱度的增加,Bi/Yb3+离子共掺杂锗酸盐玻璃近红外宽带发光强度降低。更多还原

【Abstract】 Rare-earth (RE) ions are proper activators in the photoluminescence materials due to their abundant energy levels and physical-chemical properties. The RE doped upconversion materials have potential applications in solid-state lasers, color display and information processing. Optical fiber telecommunication benefits a lot from the invention of EDFA. It should be noted that a key consideration of RE ions doped material applications is the photoluminescence efficiency since every application need high signal-noise ratio. However, at the current stage, efficiency of rare-earth doped material luminescence is still fairly low, which greatly restricts its applications.This thesis provides a comprehensive review on the upconversion, near-infrared lunminescence (NIR) and downconversion luminescence characteristics of RE ions doped materials, gives an overview of the recent progress and problems,and puts forwards their future research directions. The effect of optical basicity and struc on the upconversion, NIR, downcoversion lunminescence is inversitigated, to develop the novel light source with the typical characteristics of "estimate" and "tunable". Thermal analysis (DTA), IR absorption spectra, Raman spectra, Absorption spectra, photoluminescence spectropy (PL) were used to study the structure and lunminescence properties of the materials. A series of important conclusions and innovative results with practical significancewere obtained.The structure of alkali metal and alkali earth germanate glass are investigated. With the alkali metal and alkali earth ions increase, result in breaking the Ge-O-Ge bonds and forming Ge-O-, there are more and more NBOs in the structure, the O/Ge ratio increases and most of O2-get involoved in transition from [GeO4] to [GeO6]. And the refractive index of germanate glass under different excitation wavelengths are increased.The effect of optical basicity on the Er3+-doped germanate glasses is investigated. The materials optical basity changes by adjusting network modification of ionic radius and the concertion. It is found that, the red and green upconversion luminescence decreased with the optical basicity inceased, under980nm semiconductor laser excitation. In the alkali metal germanate glasses, the red upconversion luminescence intensity is higer than green, comparing with green up-conversion luminescence, the red up-conversion luminescence intensity decreases rapidly with increasing optical basicity, and The color of up-conversion luminescence changed from red to green. The green upconversion luminescence mechanisms is ESA, and the red is ESA, energy transfer and the non-radiative process from4S3/2level. With the optical basicity increased, the Ω6decreased, the population at the4I13/2level decreased, and then the upconversion lunminescence intensity decreased. On the other hand, the red lunminescence intensity decreased remarkably due to that, the optical basicity increased, these changes indicate that the covalency of the Er-O bond decreases, the energy transfer effecity decreased.Effect of optical basicity on broadband infrared fluorescence in Er3+-doped, Tm3+-doped, Bi-doped germanate glasses are investigated, respectively. The materials optical basity changes by adjusting network modification of ionic radius and the concertion. The study found that, the emission intensity at1.55μm in Er3+-doped germanate glass is decreased, with the increasing of optical basicity, and the Ω6, the absorption, emission cross-sections, the radiative lifetime of Er3+at the excited level4I13/2and FWHM are decreased, under980nm excitation. The effect of optical basicity on Tm3+-doped germanate glasses is same with Er3+-doped. Finally, under808nm excitation, with the optical basicity increasing, the1300nm lunminescence intensity of Bi-doped germanate glasses decreased and the FWHM increased, the NIR emission from900nm to2000nm. Under690nm excitation, it is appeared two peak position (1200nm and1400nm, respectively.) with the optical basicity increasing, the peak position move to long wavelength, the FWHM increased and higher to428nm. Through our research, the optical bacsicity could change the luminescence intensity and the FWHM.The dependence of optical basicity and Bi/Yb3+co-doped germanate glasses is also study. The optical basicity changes by adding the concertion of Yb+ion. The result shows that, under808nm excitation, there are two peaks, Bi ion of1300nm and Yb3+of1030nm which is due to the ET from Bi ion, respectively. The1300nm emission intensity of Bi ion decreased, because of the ET and optical basicity increasing. The Yb3+ion of1030nm firstly increased and then decreased with the optical basicity increase.under690nm excitation, there are three peaks, Bi ion of1300nm and1160nm, and Yb3+of1030nm which is due to the ET from Bi ion, respectively, the optical basicity increase and ET from Yb3+ion to Bi ion cause the higher1160nm NIR luminescence, the optical basicity increase and ET from Bi ion to Yb3+ion cause the lower1300nm NIR, but the effect of optical basicity on the NIR lunminescence is dominate, and lastly lead to the NIR lunminescence intensity decresed. Finally, the ET from Yb3+ion to1160nm of Bi ion is proved.更多还原