百毫焦腔内KTP光参量振荡2μm脉冲激光器

报道了一台高单脉冲能量的光参量振荡(OPO)2μm固体激光器。采用电光调Q,Nd∶YAG激光器输出的1064 nm激光,抽运腔内两块光轴方向相向放置的KTP晶体,通过双谐振光参量振荡(DROPO)技术获得2μm激光输出。OPO谐振腔由2μm反射镜、两块走离补偿的KTP晶体和2μm输出镜组成。KTP晶体尺寸为8 mm×8 mm×15 mm,切割角θ=53°,φ=0°。OPO采用Ⅱ类相位匹配(o→o+e)。当激光二极管单脉冲能量为1.02 J,电光Q开关频率为30 Hz时,获得了单脉冲能量107 mJ的简并波长2.1μm激光输出,808 nm激光二极管到2.1μm光光转换效率为10.5%,光束质量因子分别为M2x=2.38,M2y=1.56。     

1.57μ非临界相位匹配KTP参量振荡器

利用1.064μm激光泵浦非临界相位匹配（NCPM）KTP－OPO,获得了重复频率20Hz、输出能量115mJ的1.57μm激光输出。     

4～5μm全固化可调谐激光实验研究

报道了采用KTP晶体和LiIO3晶体实现4~5μm可调谐激光输出的光参量振荡器(OPO)至差频产生器(DFG)的全固化结构和相应的实验结果。其中光参量振荡器的抽运源为倍频Nd∶YAG激光,差频产生器的抽运源分别是上述光参量振荡器激光和Nd∶YAG基频激光经KTP倍频晶体后剩余的1.064μm激光。实验中Nd∶YAG基频脉冲激光脉宽12 ns,单脉冲能量300 mJ。观察到最大倍频效率达到66.7%,KTP参量量子转换效率达到50%,差频量子转换效率为1.5%,在4.45μm得到了单脉冲100μJ的激光输出。差频光的调谐范围为4.1~4.5μm,发散角为垂直方向12 mrad,水平方向4 mrad。     

种籽光注入非谐振KTP光参量振荡器

采用Nd:YAG激光倍频后剩余的1.064μm基频光抽运非临界相位匹配KTP光参量振荡器(OPO),产生的1.57μm激光作为种籽光注入到Nd:YAG 532 nm倍频激光抽运的非谐振汉晶体走离补偿的KTP OPO谐振腔中,使得OPO阈值降低30％,能量转换效率提高5％。     

腔内OPO2μm脉冲激光器

设计了基于KTP晶体的内腔式光参量振荡(OPO)2μm脉冲激光器。理论计算了KTP-OPO波长调谐特性及相位匹配参数,采用电光调QNd:YAG1.064μm激光泵浦的KTP晶体,在XZ主平面内,实现了Ⅱ类相位匹配,选用Φ4mm光阑限制光束,分别对单块KTP和为补偿走离效应采用两块向对放置的KTP晶体进行了实验,获得了最高25mJ的脉冲2.12μm激光输出,电光转化效率1.14‰。     

基于内腔的KTP光参量振荡器的腔型结构研究

实验通过设计合适的光参量振荡器(OPO)腔型结构,实现了内腔OPO的脉冲输出。采用电光调Q方式、闪光灯泵浦Nd∶YAG晶体实现高光束质量的1.064 μm基频光对Π类非临界相位匹配KTP晶体进行激发,产生1.57 μm人眼安全波段激光。对OPO 的输出波形、输出能量进行测量。在不同腔镜曲率半径下分别对OPO输出能量进行测量,绘制成泵浦电压与输出能量之间的关系,在反射镜曲率半径8 m时得到最大光-光转换效率为14.2%。这与软件模拟的实验结果一致。     

双波长输出KTP光学参量振荡器

随着人眼安全激光器在军事上的广泛应用,光电对抗需要一种能够同时输出一定能量1.5x μm激光和1.06 μm激光的OPO装置.对OPO装置的工作物质、系统结构和各项参数进行设计,并研制出1.57μm激光和1.06 μm双波长非临界相位匹配KTP光学参量振荡器(OPO).使用Nd:YAG激光器1.06 μm激光泵浦,获得12 mJ/Pulse的1.57μm激光和57 mJ/Pulse的1.06μm激光,重复频率为1 Hz,单谐振效率达到15%,光束发散角约为3 mrad.     

脉冲LD泵浦千赫兹1.57 μm全固态激光器

采用非稳腔光参量振荡（OPO）研制了千赫兹重复频率人眼安全波段全固态激光器。激光器采用电光调Q方式、脉冲激光二极管（LD）侧面泵浦Nd:YAG激光晶体实现了高光束质量的1.064m基频激光。光参量振荡部分采用Ⅱ类非临界相位匹配KTP晶体,为了获得较好的光束质量,OPO谐振腔采用平凸非稳定谐振腔结构,实现了千赫兹重频、窄脉冲1.57m波段激光输出。在脉冲激光二极管泵浦电流为125 A、电光调Q重复频率为1 kHz时,1.57m激光输出最大平均功率达到了4.67 W,激光脉冲宽度为4.3 ns,功率不稳定度为3%,激光泵浦阈值约为45 A。     

小型一体化1.57 μm人眼安全激光频率转换KTP OPO

Ⅱ类非临界相位匹配(NCPM)钛氧磷酸钾(KTP)光学参量振荡器(OPO)是获得人眼安全1.57 μm激光的重要手段.本文研制了小型一体化人眼安全1.57 μm KTP OPO,可方便地对原有激光测距机的1 064 nm Nd:YAG激光源直接进行频率转换.泵浦能量约2倍阈值处,单谐振能量转换效率约为17.5 %.     

内腔式KTP光学参量振荡器的实验研究

在脉冲氙灯抽运的Nd∶YAG被动调Q激光器腔内,插入非临界相位匹配KTP晶体,构成内腔式KTP光学参量振荡器,获得脉宽3 ns、单脉冲能量10 mJ、中心波长1.568μm的人眼安全激光输出。当光学参量振荡器的腔长分别为3 cm,6 cm和8 cm时,得到的信号光脉冲的时间宽度分别为6 ns,4 ns和3 ns。当氙灯电注入能量为26 J时,输出的信号光出现双脉冲。实验上比较了Nd∶YAG激光器不同的谐振腔结构和参量对信号光脉冲的影响,并从理论上加以解释。     

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.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

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.