飞秒激光照射银离子掺杂的 BK7光学玻璃的显微结构变化

使用聚焦的800nm,120fs,1kHz的超短脉冲激光在掺Ag^＋的BK7玻璃内部空间选择性地写入了光栅结构,然后将样品在不同温度下进行热处理.吸收光谱表明,BK7玻璃在飞秒激光照射后产生了氧空位色心,在575℃热处理后析出了银纳米颗粒.光栅的衍射效率随热处理温度的升高而减小,在575℃后又开始升高.用光学显微镜观察了光栅的结构变化并对现象产生的机制进行了分析.     

钒离子注入改进Pilkington自洁玻璃材料的亲水性研究

ActivTM玻璃是Pilkington公司推出的具有优异光催化性能和光致亲水性的自洁防雾玻璃,是近几年发展起来的新型建筑材料.其表面的TiO2薄膜的光催化性和亲水性性能都很稳定,但亲水性的光致响应时间较长.采用钒离子注入工艺对ActivTM玻璃进行掺杂改性,研究了钒离子在不同注入能量、浓度和后处理退火温度的条件下对玻璃光致亲水性的影响.研究表明,钒离子注入能够有效改善玻璃表面TiO2薄膜的亲水性,而且,较高钒离子注入能量(90keV)和掺杂浓度(6×10 16ions/cm2),玻璃光致亲水性要好,在紫外光照射1h后接触角均能小于7°,退火温度取500℃为宜.     

玻璃半导体经激光照射后变软，而后重新变硬

美国俄亥俄州立大学正在开发一种特殊玻璃，在非常小的激光能量照射下玻璃变软，而后在激光关闭后重新变硬。激光功率越大，玻璃就更软。实际表明，仅6mw的功率就可使玻璃软至其正常水平的一半。     

激光深熔焊等离子光焰图像信息提取的研究

激光深熔焊是当今制造技术发展的前沿领域。在激光深熔焊接中产生的光致等离子体光焰会随焊接过程呈周期性的变化，而焊缝的熔透性与光致等离子体光信号的累积强度有对应关系。本文通过图像处理的方法，对光致等离子光焰图像进行分析和处理，为科学分析激光深熔焊光致等离子体的机理和变化规律提供了可靠的量化数据。     

高频超短脉冲激光诱导玻璃内LiNbO3晶体生长

使用聚焦的800nm，120fs，200kHz的高频超短脉冲激光在Li20-Nb20s-SiO2系玻璃内部空间选择性析出了LiNbO3晶体．经一定条件的飞秒激光照射数秒钟后，玻璃内部激光会聚点的发光由原来的白色转变为强的蓝绿色．发光光谱测定表明，所产生韵蓝绿光为飞秒激光的倍频光．显微拉曼光谱测定表明，飞秒激光会聚处析出了LiNbO3晶体。     

Nd：碲酸盐玻璃的光谱和激光性质

对比了各种激光玻璃的光谱性质，指出碲酸盐玻璃是一咱理想的激光介质，并资产在室温下实现了钛宝石激光器泵浦了Ｎｄ：碲酸盐块体玻璃的激光发射，激光阈值４．２０ｍＪ，斜率效率１４．７％。     

氧化铅的添加对激光诱导玻璃中金纳米颗粒析出的影响

使用飞秒激光辐照和热处理相结合,通过引入PbO,实现了在含有金离子的硅酸盐玻璃内部,有空间选择性地析出大尺寸金纳米颗粒.通过吸收光谱,电子自旋共振谱和透射电镜测试研究了氧化铅对激光诱导金纳米颗粒析出的影响.实验结果表明,氧化铅的引入能抑制空穴捕获型色心生成,并促进金纳米颗粒的长大.     

激光热应力切割玻璃实验与分析

CO２激光器平均输出功率为１００W时,通过聚焦光路在玻璃表面形成圆型的聚焦点。玻璃强烈地吸 收１０畅６μm的激光,激光能量被玻璃表面１５μm厚的吸收层吸收,形成局部的应力纹样分布（设定的切割线）。 介绍了淬火气嘴将冷空气吹到玻璃表面对受热区域进行快速淬火;１００W的激光能量照射玻璃表面,产生高于玻 璃软化的温度;吹气冷却形成应力集中的热应力层,使玻璃从切开的断口沿切割线断开,断口光洁。实验证明, 激光热应力切割玻璃的最佳速度是４００mm桙s。     

掺钕氟锆酸盐玻璃激光光纤的研制

应用Ｊｕｄｄ－Ｏｆｅｌｔ理论模型和实验测定，研究了几种掺钕氟化物玻璃的光谱和荧光性质及其与玻璃化学组成的关系。结果表明，钕离在了氟锆酸盐玻璃中的发光性质要优于它在氟铝酸盐玻璃和氟磷酸盐玻璃中的发光性质，并随氟锆酸盐玻璃中氟逐步被氯所取代得到进一步的改善。应用连续浇注法制得了相 应玻璃包皮的氟锆酸盐玻璃光纤预制棒，并拉制出芯径为９μｍ掺钕氟锆酸盐玻璃光纤，该光纤在波长为５１４ｎｍ的氩激光或波长为８０     

掺铈多组分硅酸盐玻璃电子辐照着色研究

采用吸收光谱、电子顺磁共振谱和光致发光谱对掺Ce多组分硅酸盐玻璃K509在10 MeV电子辐照下的色心动力学进行了研究。结果表明, 电子辐照引起K509玻璃可见光透过率降低的色心类型为非桥氧空穴色心HC1和HC2。在剂量率一定的情况下, 色心浓度随总剂量的增大呈指数函数增大; 在总剂量一定的情况下, 色心浓度随剂量率增大呈指数函数减小。Ce³⁺荧光强度的变化表明辐照过程中Ce³⁺浓度与辐照总剂量负相关, 与辐照剂量率正相关, 验证了掺Ce玻璃耐辐照机理: Ce³⁺吸收辐照产生的空穴从而抑制空穴色心HC1和HC2的形成, 且不引入额外的可见光波段吸收。通过对Ce³⁺宽带荧光峰进行高斯拟合, 得到了K509中Ce³⁺能级结构图。     

Multiline, superbroadband and sun-color oscillation of a LiF:F(2)(-) color-center laser

We report experimental and theoretical studies of the temporal, spectral, and spatial features of a superbroadband laser. The results obtained show that the superbroadband room-temperature operable LiF:F(2)(-) color-center laser can provide low-coherence, high-intensity laser radiation with a spectral width of 1400 A centered at 1.14 mum and 700 A in the visible range from green to red and exhibit good spatial collimation with a divergence of between 5 and 6 mrad. Oscillation of all the lines of a superbroadband spectrum is completely synchronous and occurs almost simultaneously with the pump pulse, exhibiting 4-9-ns pulse delay at 20-ns pump pulse duration. Second-harmonic generation of superbroadband oscillation spectrum was realized with an overall efficiency of 10%.     

Radiation-hardness studies of high OH content quartz fibres irradiated with 500 MeV electrons

We investigated the darkening of nine high OH⁻ fibre types irradiated with 500 MeV electrons from the Linac Injector of LEP (LIL) at CERN. The transmission of Xe light was measured in situ in the 350–800 nm range. The induced attenuation at 450 nm is typically 1.52±0.15 dB/m for a 100 Mrad absorbed dose. Two-parameter fits for darkening and recovery are presented. After irradiation the tensile strength remains essentially unchanged. For Polymicro quartz core fibres the tensile strength is typically 4.6±0.4 GPa.     

Temperature-Dependent Polarization Effects in Ce:LiLuF

We report on tuned-laser, pump-probe-gain, and fluorescence yield studies of the effect that crystal temperature plays on the polarized emission characteristics of Ce:LiLuF. It was found that varsigma-polarized emission at the 327-nm fluorescence spectra peak is characterized by smaller laser pulse buildup times, higher small-signal gains, and smaller output powers than the pi-polarized 327-nm emission. We concluded that excited-state absorption (ESA) (and the resultant formation of color centers) is more severe for varsigma-polarized emission than for pi-polarized emission in this spectral region. We postulate that the enhancement in laser performance and crystal fluorescence observed with crystal cooling is due to narrowing of the ESA absorption band that reduces the probability of ESA and color-center formation.     

Stable room-temperature LiF:F2 (+*) tunable color-center laser for the 830-1060-nm spectral range pumped by second-harmonic radiation from a neodymium laser

Simultaneous photostability and thermostability of a room-temperature LiF:F2(+*) tunable color-center laser, with an operating range over 830-1060 nm, pumped by second-harmonic radiation of a YAG:Nd(3+) laser with a 532-nm wavelength has been achieved. The main lasing characteristics of the obtained LiF:F2 (+*) laser have been measured. Twenty-five percent real efficiency in a nonselective resonator cavity and 15% real efficiency in a selective resonator cavity have been obtained. The stable LiF:F2 (+*) laser operates at a 1-100-Hz pulse-repetition rate with a 15-ns pulse duration, a 1-1.5-cm(-1) narrow-band oscillation bandwidth, and divergency of better than 6 × 10(-4). Doubling the fundamental frequencies of F2(+*) oscillation made it possible to obtain stable blue-green tunable radiation over the 415-530-nm range.     

Electrode-induced nonuniformities in the sweeping of alpha quartz

Infrared absorption and scanning electron microscopic techniques show that color-center and/or electrode-metal introduction into quartz is influenced by the porosity of evaporated metal electrodes. Thermal-stress relief of electrode-metal films, during sweeping, normally causes porosity. If the porosity is extensive, H introduction predominates and color-center and electrode-metal introduction mechanisms are suppressed. Samples swept with evaporated Au/Cr electrodes relying on thermal stress-induced porosity sometimes displayed these sweeping nonuniformities. Nonuniformities were not found when samples were swept using evaporated Au-Cr electrodes containing periodic stripe openings. Uniform sweeping was also obtained using magnetron-sputtered amorphous Y-Ba-Cu-O films.     

Laser-induced darkening in thin films of fluorescein-doped boric acid glass

We report laser-induced permanent darkening in thin films of fluorescein-doped boric acid glass. The photodarkening is accompanied by a substantial increase in the absorption of the irradiated samples. The photoinduced absorption appears to be permanent. Optical and electron paramagnetic resonance measurements suggest the creation of a new photochemical species on irradiation within the absorption band of the fluorescein molecule. A possible mechanism for the photochemical change responsible for the darkening is proposed. Optical storage of information through the formation of permanent holograms is demonstrated.     

Micro-Raman spectroscopy study of surface transformations induced by excimer laser irradiation of TiO2

Pressed disks of TiO₂ powder particles (≈1 μm in size) have been irradiated with a pulsed KrF (248 nm) excimer laser source at fluences between 0.1 and 1 J cm⁻². Surface films (1.5–2 μm thick) have been studied by Raman microprobe spectroscopy and atomic force microscopy (AFM). The Raman study reveals a three-layer structure for the irradiated anatase powders. A dark layer of reduced oxide is sandwiched between a top coating of molten/resolidified rutile and an underlying defective, slightly oxygen-deficient mixed-phase of rutile and anatase. AFM measurements indicate that a smooth surface layer coexisting with the initial rough grain morphology gradually appears with increasing fluence. At low fluence, anatase is reduced in a dark film and further transformed into rutile. At intermediate fluence, a shiny coating of resolidified stoichiometric rutile forms on the dark film. It gets thicker as the fluence increases while darkening of the sublayer intensifies up to a maximum of approximately 700 mJ cm⁻². At high fluence, however, melting and re-oxidation (and eventually ablation) prevail over reduction; the whole layer turns into a greyish crust of mostly resolidified rutile in non-ablated regions. A physico-chemical mechanism is proposed to explain the in-depth distribution of the various components as a function of fluence.     

Detection of single photoluminescent diamond nanoparticles in cells and study of the internalization pathway

Diamond nanoparticles are promising photoluminescent probes for tracking intracellular processes, due to embedded, perfectly photostable color centers. In this work, the spontaneous internalization of such nanoparticles (diameter 25 nm) in HeLa cancer cells is investigated by confocal microscopy and time-resolved techniques. Nanoparticles are observed inside the cell cytoplasm at the single-particle and single-color-center level, assessed by time-correlation intensity measurements. Improvement of the nanoparticle signal-to-noise ratio inside the cell is achieved using a pulsed-excitation laser and time-resolved detection taking advantage of the long radiative lifetime of the color-center excited state as compared to cell autofluorescence. The internalization pathways are also investigated, with endosomal marking and colocalization analyses. The low colocalization ratio observed proves that nanodiamonds are not trapped in endosomes, a promising result in prospect of drug delivery by these nanoparticles. Low cytotoxicity of these nanoparticles in this cell line is also shown.     

激光辐照下的材料破坏和防护研究进展

简介了材料在激光辐照下的破坏和防护的研究进展，对激光作用下材料的破坏机理、破坏形式、影响因素和抗激光防护研究情况等进行了探讨。     

Measurement of 160-fs, 248-nm pulses by two-photon fluorescence in fused-silica crystals

Measurements of 160-fs, 248-nm ultrashort pulses are obtained through a two-photon fluorescence measurement based on the two-photon-induced color-center fluorescence in fused-silica crystals. The method proved to be reliable and advantageous in comparison with two-photon fluorescence techniques employing other materials, both solid state and gaseous.