用声光调制器进行差拍饱和光谱学的实验研究

分别用声光晶体对氩离子激光515nm谱线作幅度和频率调制,实验研究了碘吸收的差拍饱和吸收信号。用频率调制方法得到斜率极陡的一阶微商饱和吸收信号,并将它作为鉴频曲线把氩离子激光频率稳到~(127)I_2分子的P(13)43-0的a_3线上。通过与一稳定到相同精细分量上的稳频氩离子激光器拍频,绐出激光频率稳定性优于±4.7×10~(-12)。     

氦一氖0.633微米氖饱和吸收稳频激光器

利用氖原子饱和吸收峰(以下简称吸收峰)作为鉴频器,采用双通道无差调节电子学伺服系统,将氦-氖0.633微米激光进行了稳频.激光频率的稳定性优于3×10~(-10),重复性优于1×10~(-8).比稳定在兰姆下陷的氦-氖0.633微米的激光频率稳定性     

用碘和甲烷稳定的氦氖激光器的稳定性和复现性

文章介绍了碘和甲烷饱和吸收稳定的氦氖激光器的最新进展,它们的稳定性分别达到2×10~(-11)/t~(1/t)和3×10~(-12)/t~(1/t),t为取样时间,复现性达到±2×10~(-11)。633nm 碘稳定氦氖激光器是采用三次谐波锁定稳定的,它可以锁定到(127)~I_2“d”到“J”七个分量的任何一个,由碘室温度变化产生的压力位移大约15KHz/℃,碘室温度可自动控制在±0.01℃,3.39μm甲烷稳定激光是采用     

钕玻璃非线性双光子吸收

利用锁模钕玻璃激光器的单个微微秒激光脉冲,研究了掺钕激光玻璃中钕离子的非线性双光子吸收。根据实验和理论计算给出了钕离子的双光子吸收截面σ=(6.16±1.1)×10~(-33)厘米~4/瓦,非线性吸收系数γ=(1.65±0.29)×10~(-12)厘米/瓦以及光强与透过率的函数关系曲线。双光子吸收限制了钕玻璃放大器的输出峰值强度。实验确定放大器的极限峰值强度为 I_(最大)=(4.15±0.73)×10~(10)瓦/厘米~2。     

环形激光测磁系统的信号检测与稳频

本文介绍了在环形激光测磁系统中使用共同的光电检测器和预放器检测磁场信号和激光频率漂移的方法,详细介绍了系统中所用的无静差数字式稳频器。磁场产生的拍频的测量精度可达到2×10~(-5)±1Hz,1秒钟采样时激光频率稳定度可达到5×10~(-9)。     

双腔He-Ne激光器

用甲烷饱和吸收稳定的CH_4:He-Ne激光,稳定性和复现性已分别超过10~(-12)和10~(-11).其波长和频率值分别用现行~(86)Kr波长基准和~(133)Cs频率基准作了绝对测定,由此得出了目前最精确的光速值(精度为 4×10~(-9)).由于这种激光的波长处于红外波段(3.39微米),使应用受到了影响.我们的工作是在红外激光腔内增加了相应的附加腔,使红外激光变成了“可     

C—V法液晶弹性常数的测定

本文描述了近几年发展的电容—电压或电容频率测量技术,即相敏电容桥。该测量系统由计算机控制,测定频率范围为30Hz-10kHz、利用STN—0020/01SBE液晶材料在不同温度条件下测定了弹性常数K_(11)～14.9×10~(-12)N.K_(33)～15.3×10~(-2)。在玻璃板上镀金膜作为液晶分子平行取向排列层兼作为电极。本测试系统的误差和精度分别在电容值的测量误差为±5％,正弦波(30Hz—10KHz)的频率精度±1％、给出弹性常数K_(11)、K_(22)、K_(33)的误差为±5％～±10％。     

调制转移光谱稳频的研究

532nm激光的碘吸收谱线的频率被国际计量委员会(CIPM)推荐用于频率计量标准．激光频率标准对长度和时间的计量是很重要的。碘分子在532nm附近有丰富的强吸收谱线．可以作为频率稳定的绝对参考谱线。使用532nm单块固体激光器，在375kHz新的调制频率下．利用调制转移技术，将激光频率调谐到^127I2的R(56)32—0跃迁的吸收谱线，并观察到该吸收谱线相应的15条超精细结构分量。通过展宽的调制谱线可以看出375kHz的调制频率得到比312kHz调制频率更高的鉴频敏感度．并在实验上成功地将激光频率稳定在碘的超精细吸收谱线的α10，分量上长达10h，估计稳定度在10^-13量级。准确的频率稳定性正在两台激光器上用拍频的方法进行测量。     

原子束激光诱导荧光法测锂原子2~2P←2~2S跃迁的超精细结构和同位素位移

我们使用的原子束发散角为4.7×10~(-3)弧度,残余多谱勒宽度7兆赫;一束线宽为6兆赫的可调谐染料激光与它正交。激光诱导荧光信号经调制接收放大后予以记录,使激光频率在30GHz范围扫描。测得~6Li 和~7Li 的2~2P 能级的精细结构分裂分别为9.7±0.4和10.5±0.5GHz;2~2P_(1/2)能级的同位素位移为10.7±0.6GHz。激光频率作2.5GHz 扫描。光强4毫瓦/厘米~2时,测得~7Li 的2~2P_(1/2)←2~2S_(1/2)跃迁的四条超精细结构谱线的间距依次为88±11,730±73,92±7MHz,     

利用取样积分实现激光饱和吸收一次谐波稳频

对激光器进行频率调制.检测原子分子饱和吸收信号中的一次谐波成分得到频率误差信号,反馈控制可以实现激光频率的稳定.介绍了取样积分提取一次偕波信号的原理和利用单片机实现的取样积分和数字比例积分微分(PID)控制的技术.相对于传统的锁相放大和模拟PID技术,取样积分和数字PID结构简单,可靠性高,调试方便,实现难度大大降低.建立的Cs原子饱和吸收外腔半导体激光(ECDL)稳频系统,估算相对频率波动优于1.2×10-9(p-p),平均锁定时间可达7天,并实现了自动扫描饱和吸收峰、自动锁定和意外失锁的自动重新锁定功能.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.