缓冲气体压力对铷原子吸收特性的影响

铷原子吸收线宽很窄,通过充入定量缓冲气体,可以加宽铷原子的泵浦吸收线宽,从而可以提高铷原子对泵浦光的吸收效率。通过计算模拟,找到入射泵浦光谱宽、入射泵浦强度和缓冲气体压力之间的对应关系,找到最佳的实验工作条件,最终实现铷原子对离泵浦中心频率一定范围内的泵浦吸收效率很高,同时保证在泵浦谱宽范围内的总泵浦吸收效率也很高。模拟结果显示：随着缓冲气体压力的增大,铷原子吸收线宽不断增加,但是泵浦光的总吸收效率下降的并不明显。     

亚自然线宽双光子光谱学

本文叙述了亚自然线宽双光子光谱学的基本原理。分析了观察亚自然线宽的最佳条件。给出了衰减多脉冲光激发的双光子吸收几率的表达式。提出了一种简单易行的实验方案。     

水汽分子振转Hamiltonian常数的拟合及碰撞加宽线宽的理论研究

0.6-1.0μm区域大气分子的吸收特性是目前强激光传输领域中的一个重要课题,大气分子的吸收特性一般由线位、线强、线宽和线宽的温度依赖指数等参数来描述。水汽分子是大气分子中最重要的吸收分子,在这一区域人们对水汽分子的碰撞加宽线宽的研究并不多,特别是对一些弱带的研究不仅在实验上、而且在理论上都未见报导。为此本工作首先根据现有的线位参数,用最小二乘法首次拟合了水汽分子(122)振动带的Hamiltonian常数,我们采用的是Watson型Haniltonian,其形式为。     

开放系统中位相涨落对增益和色散的影响

本文研究了开放的简单三级级无粒子数反转激光系统中驱动场位相涨落对增益和色散的影响。发现,驱动场位相涨落将导致有限线宽,随着这个线宽的增加,增益和色散将单调地减小,当线宽不为零时,在零吸收有够产生的大折射率,这与从封闭的V型三能级系统得到的结论大不相同。     

基于超窄线宽激光器的多气体光声光谱检测研究

针对多组分痕量气体检测中精确度差、灵敏度低等问题,设计了基于光源波长扫描技术的光声光谱式多组分痕量气体检测系统。系统采用单一超窄线宽半导体激光器作光源,设计了一阶纵向共振式多光程吸收光声池,通过正弦信号对光源波长进行调制,并结合二次谐波信号检测技术和超窄线宽激光特性,有效地消除了吸收池内的背景噪声和光源抖动的影响,实现...     

种子光线宽影响端面抽运碱金属蒸气放大器的输出特性

半导体激光器抽运碱金属激光器(DPAL)是近年来发展迅速的新型激光光源。DPAL的主振荡功率放大(MOPA)系统是实现DPAL高功率化的最理想工程手段之一。相对于传统激光器,DPAL的吸收和发射线宽非常窄,因此种子光的线宽是影响DPAL-MOPA输出特性的重要参数之一。建立端面抽运DPAL-MOPA系统的微观动力学理论模型,在计算步骤中考虑了种子光线宽与发射截面的波谱分布,详细计算和分析了种子光线宽对DPAL-MOPA系统的输出功率、输出线宽、提取效率、增益系数和抽运吸收等特性的影响,有助于将来定标放大高功率DPAL系统的构建。     

ArF和KrF放电激光器的调谐

用棱镜对充分钝化的双放电受激准分子激光器作简单调谐，结果使ArF和KrF的调谐范围超过20埃。这两种调谐都不是连续的，为自吸收区域内的非激射小孔所中断。双棱镜组的色散使KrF线宽为1~2埃，ArF线宽小于0.5埃。     

大能量窄线宽全固态钛宝石激光器的研究进展

主要介绍了用于差分吸收激光雷达系统和蓝绿激光通信的大能量、窄线宽全固态脉冲钛宝石（Tn：Al2O3）激光器的应用及其在国内外的研究历史和现状。阐述了目前获得大能量、窄线宽全固态钛宝石激光器的几种典型方法,比较了其优缺点,并对这种激光器的发展前景进行了展望。     

全光纤窄线宽脉冲激光器

介绍了一种全光纤窄线宽脉冲激光器。该激光器由两部分组成,即脉冲光纤激光器种子和由隔离器、耦合器以及光纤光栅组成的窄线宽脉冲提取装置。脉冲光纤激光器种子是基于半导体可饱和吸收镜(SESAM)为锁模机制的全光纤被动锁模激光器,输出脉冲的光谱宽度约为3 nm。窄线宽脉冲提取部分对脉冲光纤激光器种子输出脉冲的光谱进行提取、窄化,输出脉冲的光谱宽度约为0.1 nm。该激光器操作简单、设备简易,为全光纤结构;不仅可以输出窄线宽光脉冲序列,而且同时还可以输出脉冲光纤激光器种子的光脉冲序列,极大地拓展了脉冲光纤激光器的应用范围。     

用于Rb蒸气激光泵浦的可调谐窄线宽半导体激光器

由于Rb蒸气的吸收峰随缓冲气体气压存在漂移,利用体布拉格光栅(VBG)实现线宽压窄的同时,实现泵浦半导体激光器中心波长的可调谐也是十分必要的。本文采用国内封装的半导体激光阵列(LDA),利用VBG的温度特性,实现了线宽不大于0.3nm的同时,激光器中心波长从779.89nm到780.35nm可调谐。该激光器可以通过叠阵方式用于Rb蒸气的泵浦和激励。     

PCB线宽检测设备的发展现状与趋势

印制电路板(PCB)在向高密度化和高性能化方向发展,导线精细化已成PCB生产的必然要求。在导体精细化过程中控制上线宽度和下线宽度以保证导线的电特性要求,已成各PCB生产厂家急需解决的关键问题。本文通过对目前常用PCB线宽检测设备的优缺点进行分析,提出了采用数字图像处理技术与照明技术的新一代的线宽/间距检测仪器设备,将成为印制板厂线宽检测的必备测量工具。     

声表面波器件光刻的衍射效应研究

声表面波(SAW)器件光刻过程中,制作的光刻胶线条宽度与掩模版不一致,特别是不同宽度的非均匀线条光刻后线宽变化值存在偏差。该文研究了接近式曝光衍射效应对线宽的影响,分析了掩模版上线条和缝隙宽度、衍射光强、掩模版与光刻胶间距等参数间的关系。结果表明,通过建立光学模型给出了计算曝光后不同线条宽度变化值的方法,采用程序编程可对掩模版数据中不同尺寸的线条和缝隙宽度进行补偿,实现SAW器件非均匀线条宽度的精确控制。     

双层悬空结构射频微电感制作研究

利用MEMS工艺制作了一种双层悬空结构的圆形射频微电感,研究了双层结构微电感中微带线宽度对其性能的影响。研究表明,双层悬空结构的圆形射频微电感不仅具有较大的电感量,而且其Q值也较高;双层微电感的Q值随微带线宽度的增大而升高,而电感量则随微带线宽度的增大而降低。对于微带线宽度为60μm的双层微电感,在频率2～4GHz时,其电感量可达到5nH左右,Q值达到20。     

Analysis of instability in a critical dimension bar due to focus and exposure

In the photolithography processing of semiconductor, the line width becomes smaller and smaller. Therefore, the requirements of process window are stricter than before. Among them, the control of focus and exposure dose is one of the most important factors that may affect the line width. Bad control of focus and exposure may not only affect line width, but also cause the increment of rejects of products. The research mainly explored the effects of focus and exposure dose on line widths of different photo resists. The research obtained related coefficients of exposure dose line width and focus line width by coating photo resist of different components on the surface of the silica wafer. The results of research found that focus may not only change line width but also had a positive–negative symmetric relationship with line width. It also found that there was linear relationship between exposure dose and line width.     

布里渊激光雷达系统中的关键因素研究

基于德拜热运动的弹性波理论,考虑激光雷达的光散射效应,提出了布里渊激光雷达系统中的布里渊线宽的选择方法,并推导出散射光谱中的斯托克斯线和反斯托克斯线两条伴线的相对频移公式;分析指出,在介质中,由于弹性波总是有衰减,所以,布里渊谱线的线宽不为零;建立了布里渊激光雷达系统实验模型,通过选取适当的参数进行模拟计算,进一步讨论了布里渊线宽与海水温度的关系;得到了不同海水温度下的布里渊线宽曲线,从而清晰的表明,在激光雷达系统中,布里渊线宽并不是一个常值,在其他参量不变的情况下,随着海水温度的升高,布里渊线宽会逐渐变窄。     

Numerical Study of Open Slot Lines with Asymmetrically Placed Strip Conductor in 37.5–78 GHz Frequency Band

Slot lines with strip conductors asymmetrically placed on a finite size substrate have been rigorously studied by means of the singular integral equation method (SIE). Dependences of the propagation constant on the frequency for different slot line sizes (substrate width, strip conductor width as well as the distance from the substrate edge, slot width and substrate thickness) were determined in the 37.5 – 78 GHz frequency. What we analized was a) how the substrate thickness and slot width affected the number of modes propagating in the slot line and b) what the size of the line should be to ensure propagating of only one mode (this is important in practice).     

基于频率补偿的窄脉冲量子级联激光器快速驱动技术

脉冲量子级联激光器(QCL)因自热效应会导致谱线展宽,故需极短的电流脉冲驱动。理论极限线宽所需的脉宽为5~15 ns,但由于环路寄生参数的影响,窄脉冲会引起信号过冲或振荡,因此目前商用的QCL驱动器无法满足这个要求。为获得更理想的激光器线宽,在常规脉冲恒流电路的基础上,采用频率补偿的方法来消除过冲和振荡,并设计了一款稳定的纳秒级激光器驱动电路。实验结果显示该驱动装置实现了峰值电流0~2 A、脉宽8.4~200 ns、上升时间4 ns、过冲1%的脉冲电流输出。使用中国科学院半导体研究所研制的波长4.6m激光器和傅里叶变换光谱仪进行测试,当驱动脉宽由100 ns减小到10 ns时,激光器线宽由0.35 cm-1线性递减到0.12 cm-1。综合验证表明,所设计的驱动装置实现了稳定的窄脉冲电流输出,尤其适用于量子级联激光器的窄线宽驱动及应用。     

1550 nm全光纤单频脉冲光纤激光器

设计并实现了一种基于人眼安全波段的1550 nm全光纤化结构单频脉冲光纤激光器。激光器采用外腔稳频技术的单频半导体激光器作为种子源,其线宽1.8 kHz,功率20 mW。通过预放大器和声光调制器获得单频脉冲激光,并运用两级光纤放大器实现了线宽1.9 kHz、平均功率521 mW、脉冲宽度200 ns、重复频率10 kHz的单频脉冲光纤激光输出。输出脉冲峰值功率达260 W。输出端采用了双包层单模光纤,保证了输出激光的光束质量。整个激光器通过对种子光级联放大,结合放大器的增益控制,成功抑制了受激布里渊散射(Stimulated Brillouin Scattering,SBS)效应,消除了放大过程中噪声对线宽的影响,获得了线宽稳定的单频脉冲激光。     

Analysis of instability line width and white wall created by the photolithography process

In the photolithography processing of semiconductor, line width is smaller and smaller. Therefore, the requirements of process window are stricter than before. In the small line width, the formation of serious white wall will affect line width and cause rejects in following process. The study conducted research on the control of best focus in which particularly explored the relationship between exposure dose and line width and the phenomenon of white wall generated by focus. The research obtained related coefficients of exposure dose-line width and exposure dose-white wall by coating photo resist of different components with the same thickness on the surface of fused silica wafer. The results of research found that exposure dose might not only change line width but also had important effects on white wall. Among others, the most important factor for exposure dose is the component of sensitivity of photo resist.     

A global interconnect optimization scheme for nanometer scale VLSI with implications for latency, bandwidth, and power dissipation

This paper addresses the critical problem of global wire optimization for nanometer scale very large scale integration technologies, and elucidates the impact of such optimization on power dissipation, bandwidth, and performance. Specifically, this paper introduces a novel methodology for optimizing global interconnect width, which maximizes a novel figure of merit (FOM) that is a user-defined function of bandwidth per unit width of chip edge and latency. This methodology is used to develop analytical expressions for optimum interconnect widths for typical FOMs for two extreme scenarios regarding line spacing: 1) spacing kept constant at its minimum value and 2) spacing kept the same as line width. These expressions have been used to compute the optimal global interconnect width and quantify the effect of increasing the line width on various performance metrics such as delay per unit length, total repeater area and power dissipation, and bandwidth for various International Technology Roadmap for Semiconductors technology nodes.