Effects of Nb2O5 on thermal stability and optical properties of Er3+-doped tellurite glasses

Er³⁺-doped tellurite glasses with molar compositions of xNb₂O₅-(14.7-x)Na₂O--10ZnO--5K₂O--10GeO₂-- 60TeO₂--0.3Er₂O₃ (x=0, 3, 5, 7 and 9) have been investigated for developing 1.5~μm fibre and planar amplifiers. The effects of Nb₂O₅ on the thermal stability and optical properties of Er³⁺-doped tellurite glasses have been discussed. It is noted that the incorporation of Nb₂O₅ (x=5) increases the thermal stability of tellurite glasses significantly. Er³⁺-doped niobium tellurite glasses exhibit a large stimulated emission cross-section (7.2\times 10^-21- 10.7×10^-21~cm² and the gain bandwidth, FWHM×\sigma_e^{\rm peak} (274\times 10^-28 - 480×10^-28~cm³), which are significantly higher than that of silicate and phosphate glasses. In addition, the intensity of upconversion luminescence of the Er³⁺-doped niobium tellurite glasses decreases rapidly with increasing Nb₂O₅ content. As a result, Er³⁺-doped niobium tellurite glasses might be a potential candidate for developing laser or optical amplifier devices.     

紧凑型双波段无热化红外光学系统设计

针对红外双波段量子阱探测器,设计了一个可同时工作在4.4～5.4mm（中波段红外）和7.8～8.8mm（长波段红外）波段的仅含3片透镜的紧凑型双波段无热化光学系统,有效焦距为30 mm, f/#为2.1。对比先前报道的双波段无热化红外光学系统,此设计仅采用硫系玻璃材料Ge20Sb15Se65制备的两片镜片和常规红外材料ZnS制备的一片镜片,通过合理分配各个镜片的光焦度达到系统在中波红外及长波红外两个波段的无热化设计效果,且不含衍射面,整体结构紧凑,制备难度低。利用硫系玻璃易于精密模压制备非光学球面的特点,仅在一片硫系玻璃镜片上设计一处非球面。设计结果显示,系统在两个红外波段,－40℃～60℃温度范围内像质良好,且光学调制函数（MTF）接近衍射极限。     

钕磷酸盐激光玻璃中金属铂颗粒的产生与迁移

给出了钕磷酸盐激光玻璃中可能存在的铂磷酸盐、偏磷酸盐化合物的热力学参数.利用这些参数,研究了激光玻璃熔制过程中可能发生的液-固、气-固、气-液等化学反应的方向和限度,分析了玻璃中金属铂颗粒的可能来源、存在方式及迁移过程.结合实验讨论了铂的产生及迁移、最佳除铂工艺途径和钕磷酸盐激光玻璃的除铂机理.     

Laser-diode excited intense upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses

We have investigated infrared-to-visible upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses. The UV cutoff wavelength is shortened while its lifetime is increased almost linearly, with PbF2 substituting for PbO in the bismuth-lead germanate glasses. Three emissions centred at around 529, 545 and 657 nm are clearly observed, which are identified as originating from the ^2H11/2→^4 I15/2,^4S3/2→^4 I15/2 and ^4 F9/2 →^4 I15/2 transitions, respectively. It is noted that all the upconversion emission intensities increase with PbF2 concentration increasing. The ratio between the intensities of red and green emissions increases with the increasing of PbF2 content. Energy transfer processes and nonradiative phonon-assisted decays account for the populations of the ^2 H11/2,^4 S3/2 and ^4F 9/2 levels. The quadratic dependence of fluorescence on excitation laser power confirms a two-photon process to contribute to the upconversion emissions.     

Ce3+对Er3+/Yb3+共掺氟磷酸盐玻璃光谱性质的影响

研究了能量接受离子Ce3+对Er3+上转换发光强度以及Er3+在1.5 μm附近波段发光性能参数的影响,并从能量匹配及能级结构角度出发对Er3+/Ce3+间的能量转移机制进行了分析.分析认为,4 I11/2能级的Er3+通过无辐射能量转移把能量传递给2F5/2能级的Ce3+激发其跃迁至2F7/2能级,而4I11/2能级上的Er3+则无辐射弛豫至4I13/2能级,从而有效降低氟磷酸盐玻璃中Er3+的上转换发光.当Er3+浓度为1.11×1020 cm-3时,Ce3+的最佳掺杂浓度为2.22×1020 cm-3,此时Ce3+的引入不仅可以降低上转换发光,而且有助于提高Er3+在1.5 μm附近波段的荧光强度、发射截面以及4I13/2能级荧光寿命.     

大口径硫系玻璃内部缺陷检测物镜设计及实验验证

大口径硫系玻璃在军事及民用高分辨率红外夜视成像领域有着重要的应用价值。现阶段缺少针对大口径硫系玻璃内部缺陷（包括条纹、杂质和裂纹等）进行量化评价的检测技术,因此硫系玻璃的品质控制成为了限制其大范围发展的瓶颈之一。针对课题组大口径硫系玻璃的透射光谱特性以及现有的近红外照相机的光谱响应特性,提出了一种工作在近红外波段的大口径硫系玻璃内部缺陷检测技术并设计成像镜头,镜头包含了使用K9、F6玻璃的三片双胶合透镜,有效焦距为200 mm,在近红外波段0.95～1.05 m实现消色差,成像质量接近衍射极限。根据镜头特点搭建了大口径硫系玻璃内部缺陷测试装置,实验验证了镜头的分辨率与设计要求相符,并可针对大口径硫系玻璃的各种内部缺陷进行有效检测。     

高折射率光学薄膜的化学法制备研究

报道了一种以ZrOC12·8H2O为源,溶胶-凝胶法制备高激光负载高折射率薄膜的新方法。薄膜采用旋转镀膜法制备,对薄膜的结构、光学特性及激光损伤阈值进行了测量,有机粘接剂对薄膜折射率及机械强度的影响也作了探讨。以该薄膜与SiO2溶胶凝胶膜交替涂覆制成的多层高反膜,剩余透过率仅0.98%,激光损伤阈值达16J/cm2（3ns）。     

Gain Characteristics of Er^3＋-Doped Phosphate Glass Fibres

An erbium-doped phosphate glass fibre has been drawn by the rod-in-tube technique in our laboratory. The gain for the Er^3＋-doped phosphate glass fibre with different pump powers and with different input signal wavelengths is investigated. The 2.2-cm-long fibre, pumped by a single-mode 980-nm fibre-pigtailed laser diode, can provide a net gain per unit length greater than 1.SdB/cm. The pump threshold is about 50mW at the wavelength of 1534nm, and below 70roW at 1550nm. The gain linewidth of the Er^3＋-doped phosphate glass fibre is greater than 34 nm and can cover the C band in optical communication networks.     

Enhanced near infrared emission in water-soluble NdF3 nanocrystals by Ba2+ doping

A simple and efficient method for the synthesis of water-soluble NdF3 and NdF3:Ba2+ nanocrystals under hydrothermal conditions is established. The method involves the coating of the nanocrystals with a layer of hydrophilic polymer polyvinylpyrrolidone (PVP). The as-prepared products are characterized by powder X-ray diffraction, field emission scanning electronic microscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy. The PVP coating transforms the nanocrystals into a biocompatible material and improves the fluorescence intensity of NdF3 in the near infrared (NIR) region. The morphology of the nanoparticles changes, whereas the fluorescence intensity of NdF3 in the NIR region increases when a small amount of Ba2+ is doped into the NdF3/PVP nanoparticles.     

Yb3+/Er3+共掺锗碲酸盐玻璃上转换发光增强机理的研究

玻璃的最大声子能量决定稀土离子的上转换发光强度，但本研究发现：Yb^3 ／Er^3 共掺锗碲酸盐玻璃在980nm LD抽运下，上转换荧光强度随着Bi2O3对PbO的取代和碱金属离子半径的增大而明显增强．而Raman光谱显示基质玻璃的最大声子能量并不随Bi2O3对PbO的取代和碱金属离子半径的增大而变化，但玻璃的最大声子密度随着Bi2O3对PbO取代和碱金属离子半径的增大而降低．从玻璃无辐射跃迁概率的角度，通过分析表明，最大声子密度的降低是玻璃上转换发光强度增强的主要原因．