脉冲激光作用于硅的受激发光特性

用脉冲激光作用在硅基上产生表面等离子体波,在氧气和空气氛围中加工生成硅氧化量子点结构,有很强的光致荧光（PL）发光,发光效率可达20%;经高温快速退火处理后,在700 nm波长邻域观察到受激发光峰,检测到明显的光学增益和阈值行为,其受激发光峰最窄的半高宽可达0.5 nm。通过第一性原理模拟计算,发现硅氧化量子点结构表面钝化成键的类型与密度是形成受激发光的关键,并由此提出相应的物理模型。     

基于改进的单次自相关测量飞秒激光脉冲的时空特性(英文)

针对单次自相关方法只能测量一个脉宽的缺点,提出一种改进的单次相关方法测量超短激光脉冲全空域中不同空间位置的时空特性.通过实验测量了钛宝石激光器输出飞秒激光脉冲的时空特性,结果表明飞秒激光脉冲全空域中不同位置的复杂空间特性得以精密测量;不同空间位置的时间脉宽不同,它们服从高斯分布;当飞秒激光脉冲经过二硫化碳非线性介质传输后,随着输入平均功率的增加,同一空间位置的时间脉宽呈现慢慢变窄的趋势.实验结果验证了所提方法可以有效地测量超短激光脉冲全空域中不同空间位置的时空特性.     

超短脉冲激光烧蚀SiO2材料的库仑爆炸模型理论分析

基于动理论Vlasov-Poisson方程,建立了超短脉冲激光引起的SiO2材料表面库仑爆炸烧蚀机理的理论模型,计算了在多光子吸收与雪崩2种电离机制下材料中自由电子的非平衡态分布,并在此基础上定量分析了自洽电场导致的材料表面库仑爆炸的机理及激光参数对材料表面烧蚀的影响.结果表明,在飞秒激光作用下自由电子弛豫时间不是常数...     

脉冲CO2激光骨硬组织消融和电锯截骨的形态比较

评估脉冲CO2激光用于骨硬组织消融的可行性和有效性.以脉冲CO2激光为辐射源,动态扫描方式进行骨硬组织消融实验,以电锯传统手术器械为对照组,体视显微镜和扫描电子显微镜（SEM）观察骨组织弹坑的形态学变化.系统比较激光消融技术与传统手术器械在切口表面形貌、微结构变化等方面的优劣.实验结果表明：脉冲CO2激光可以获得类似电锯截骨的效果,并具有清洁、易操作等优势.     

飞秒脉冲激光烧蚀靶材机理的探讨

飞秒脉冲激光烧蚀靶材的研究发现,激光和靶材的相互作用不遵守傅立叶定律,热烧蚀模型不再适用。本文首先分析了研究超短脉冲激光烧蚀过程中电子和离子亚系统之间相互作用程度的双温模型,由此出发,结合飞秒脉冲激光的特点,探讨了非平衡烧蚀机理,并根据相应实验数据说明了飞秒激光烧蚀靶材的机制是非平衡态下的烧蚀。     

超快激光脉冲的产生和放大

超快激光脉冲是实现超高速通信最为重要的部分.近十年来,啁啾脉冲放大技术和宽带增益介质的结合,高功率超快激光脉冲取得了迅猛的发展.在小型实验室桌面激光器就可以产生数太瓦功率的激光.本文介绍了用啁啾脉冲放大技术实现超快脉冲的产生和放大.     

Numerical simulation of residual stress field induced by laser shock processing with square spot

Laser shock processing (LSP), also known as laser peening, is a novel surface treatment technique in the past few years. Compressive residual stresses which imparted by LSP are very important for improving fatigue, corrosion and wear resistance of metals. Finite element analysis (FEA) simulation using ABAQUS software has been applied to predict residual stresses induced by LSP on Ti-6Al-4V titanium alloy with laser pulse duration 30 ns and water confined ablation mode. The residual stress field generated by different shape laser spots was studied, and the square laser spot is shown the most suitability for avoiding stress lack phenomenon and overlapping LSP. Surface residual stresses and plastically affected depth within single square spot both increased with the increase of laser intensity and laser shock times. Furthermore, compared with circle and ellipse spot, the residual stress distribution in overlapping square spots is very uniform only with small overlapping ratio. LSP with square spot can process advantageous residual stress field, and this technique will be used widely.     

激光干式除漆的声波监测与分析

利用激光除漆过程中会产生声音信号,通过实验的方法,用声音记录装置记录下激光除漆过程中的声波信息,并且对采集到的声波信息分别进行了时域和频域分析.从声音信号的时域分析可以得到漆层被清洗前后声波信号强度没有显著变化,说明短脉冲激光干式除漆的主要作用原理是基底振动效应,而不是烧蚀效应.从声音信号的频域分析可以得到漆层被清除前后谱峰位置有明显的不同,依据谱峰的变化情况可以辨别漆层是否被清洗干净,为激光除漆提供了一种新的判断依据.     

一种新的波长可调谐光脉冲的生成方案

提出了一种利用两个F-P半导体激光器双向注入锁定产生波长可调谐光脉冲的实验方案,可生成双波长可调谐光脉冲.利用光纤光栅(FBGs)作为滤波元件,通过应力作用在两个光纤光栅上以改变它们的反射波长和适当调整可调谐光延迟线(VODL)长度,可得到不同波长的光脉冲输出,而重复频率保持524.6MHz不变.在13.2nm调谐范围内边模抑制比高于25dB,系统稳定且波长调节便利.     

用电光偏转器实现激光脉冲稳幅的优化研究

阐述用高压电脉冲发生器驱动LiNbO3电光偏转器，对激光脉冲进行快速偏转．产生幅度稳定激光脉冲输出的工作原理．分析由冷阴极管、雪崩管和MOS管制成的电脉冲发生器对输出激光脉冲幅度稳定性的实验结果．比较这三种电脉冲发生器对激光脉冲的稳幅作用．发现用雪崩管或MOS管代替进口冷阴极管制成的高压电脉冲发生器，同样获得优良的激光脉冲稳幅的效果．这一结果对于光电器件国产化研究有一定的实际意义．     

Calcium Phosphate Coating on Al2O3 Ceramics by a Biomimetic Method Using Electric Pulse Technique

The preparation of calcium phosphate (CP) coating on alumina ceramics using electric pulse stimulating method has been investigated. The cup-shaped alumina ceramics were soaked in a simulated body fluid ( SBF), and a square pulse potential with frequency of 1 Hz and voltage of 110 V was applied between the inner and outer surfaces of the alumina cup. Surface morphology of CP coatings during different deposition periods was observed by a Philips XL-30 scanning electron microscope (SEM). Compositional analysis was examined by EDAX. The mechanism of nucleation and growth of CP coating was discussed. SEM result indicates that the coating comprises of a large number of tiny needle-like grains and has a porous microstructure. There is a strong bond between the deposited layer and Al2O3 substrate, which may be due to the gentle growth of the biomimetic method. The EDAX analysis indicates that main composition of the coating is calcium and phosphor. The formation of CP coating may be contributed to the stimulation of electric pulse and the high ions concentration which is 1.5 times of the concentration of SBF solution ( 1.5SBF solution). Such surface functionalization method by electric pulse potential can be used to prepare CP coating on various electric-insulating bioinert materials for improving their bioactive character.     

较高气压下激光烧蚀等离子体的动力学特性

建立一维半导体Ge的激光烧蚀模型,对波长为248nm,脉宽为17ns,峰值功率密度为4×108w/cm2的KrF脉冲激光在1000torr(1torr=133.32pa)氦气环境下烧蚀晶体Ge及产生等离子体的过程进行了数值模拟,并对计算结果进行分析比较.结果表明在惰性气体环境下,气压在1torr和1000torr之间变化对等离子体屏蔽现象的出现几乎不产生影响;背景气压的增大抑制了粒子的扩散,使等离子体的膨胀速度减小,限制了其膨胀的空间.     

Supercontinuum Generation in DSF Pumped by Actively Mode-Locked Fiber Laser

The supercontinuum （SC） generation at the repetition rate of 10 GHz is presented. The SC is generated in a 4.2 km conventional dispersion-shifted fiber （ DSF）, which is produced with nonlinear effects and group velocity dispersion. The DSF is pumped by an actively mode-locked Er^3＋ -doped fiber laser with pulse width of 7. 97 ps. A novel SC pulse source with a bandwidth up to 125 nm is obtained, which covers the whole C, L bands and part of S band. The stable, narrow pulses with mean pulse-width of 9.7 ps and time-bandwidth product of 0. 48 are filtered out across the whole SC bandwidth. This supercontinuum pulse source is suitable for future high-speed optical communications.     

NaClO/IPA体系制备单晶硅太阳能电池绒面的研究

采用NaClO和IPA体系对单晶硅各向异性腐蚀制备绒面。通过紫外可见光光度计和扫描电镜对硅绒面的反射率、形貌进行了表征。结果表明,当NaClO为10%（质量分数,下同）, IPA为5%,腐蚀温度为80℃,腐蚀时间为15 min时,能够得到均匀单晶硅绒面,硅片平均反射率达15%左右;与传统的NaOH/IPA腐蚀体系相比,该工艺制得的单晶硅绒面结构反射率低,有利于太阳能电池性能的提高。     

脉冲激光烧蚀固体：从正常蒸发转变到相爆炸

本文系统地讨论了脉冲激光烧蚀固体材料时,随激光能量密度的增加,从正常蒸发转变到相爆炸的全过程。首先提出正常蒸发情况下的烧蚀模型,利用此模型,基于Ni靶材,得到激光的透射率随时间的演化规律,以及烧蚀厚度随激光能量密度的变化规律,将所得结果比实验值进行了详细地比较分析,发现我们的结果与实验值达到令人满意的吻合。其次,还讨论了脉冲激光烧蚀靶材时,随激光能量密度变化,烧蚀过程中将出现的亚表面加热,正常沸腾及相爆炸现象。     

不同条件下激光诱导金属铝等离子体的发射谱研究

用钕玻璃激光器(～25J)烧蚀铝靶获得等离子体，以氩气作为保护气体，分析了环境气压、等离子体的观测高度、激光功率密度对谱线强度的影响，并进行了讨论．     

荧光法表征沉积在硅片上的金图形

利用硅片上的金表面形成半胱胺自组装膜,并在半胱胺膜上接上荧光物质异硫氰酸荧光素,用落射荧光显微镜及电子倍增电荷耦合器件间接表征沉积在硅片上的各种金图形．该方法简便,灵敏度高,表征出的金图形清晰,最小直径为5—7μm．     

有用脉冲中干扰脉冲的去除方法

在使用计算机对外部脉冲进行计数的过程中 ,由于干扰脉冲的存在 ,计算机得到的脉冲数往往比实际的脉冲数要多 .为了得到脉冲的准确数值 ,必须想办法把干扰脉冲去掉 .本文介绍了从硬件和软件两方面去掉干扰脉冲的方法 .     

基于集群磁流变单晶碳化硅基片抛光加工的工艺研究简

基于集群磁流变效应超光滑平面抛光理论及试验装置对单晶碳化硅基片进行了平面抛光试验,结果表明,金刚石磨料对单晶Sic基片具有较高的材料去除率;加工间隙在1．5I砌左右具有较好的加工效果,随着加工时间的延长表面粗糙度越来越小,且30min内表面粗糙度变化率达到89％以上。通过优化工艺参数对单晶SiC进行集群磁流变平面抛光,发现经过30min加工,表面粗糙度Ra从42．1m下降到4．2nm,表明集群磁流变效应平面抛光用于加工单晶SiC基片可行且效果显著。     

Improving the sensitivity of protein microarray by evanescent-field-induced fluorescence

To improve the sensitivity of protein microarray, a prism surface replaces the surface of the common microscope slide. The protein targets arrayed on the surface are hybridized and labelled by fluorescent probes. Evanescent excitation occurs when the convergent laser reaches the surface, and a photomultiplier tube detects the emitted fluorescent signal. A two-dimensional actuator scans the whole surface to achieve planar laser excitation and fluorescence collection. The penetration depth of the evanescent field into the protein targets is only some hundred nanometers and can be controlled by different incident angle of the laser beam, so the undesired background signals are reduced dramatically and the detection sensitivity is improved by a factor of 50 to 100 comparing to confocal excitation. This approach can detect low abundance analytes without signal amplification.