高重频Nd:YVO4声光调Q与RTP电光调Q激光器实验对比分析

报道了相同实验条件下激光二极管端面抽运生长型复合Nd:YVO4晶体声光调Q和RTP电光调Q激光器。应用声光调Q和RTP电光调Q分别实现了最高重复频率200 kHz和500 kHz的TEM00模1 064 nm激光输出,输出平均功率分别达到12.13 W和13.56 W,脉冲宽度分别为16.65 ns和27.27 ns,并首次对比了两种调Q体制下的高重频激光输出特性。实验结果表明,RTP电光调Q具有更好的高重频关断能力,但由于受到高压驱动的限制,RTP电光调Q无法在更高重复频率下实现窄脉宽高峰值功率激光输出,而在更高重频下仍有较好输出性能的声光调Q将取代电光调Q成为几百千甚至上兆Hz高重频激光器的首选调Q机制。     

150kHz生长型复合Nd:YVO4/Nd:GdVO4电光调Q激光器

报道了一种激光二极管(LD)端面抽运生长型复合晶体的RTP电光调Q激光器,实现了最高重复频率150kHz的TEM00模激光输出,并且对比了生长型复合Nd:YVO4和Nd:GdVO4晶体在高重复频率电光调Q激光器中的表现。实验表明在中小抽运功率下,具有更大发射截面和适中上能级寿命的复合Nd:YVO4晶体更容易在高重复频率电光调Q运转下实现高峰值功率的窄脉宽激光输出。在高抽运功率下,相比于复合Nd:YVO4晶体,热性能更加出色的复合Nd:GdVO4晶体更适合作为高重复频率电光调Q运转的激光增益介质。     

500 kHz,6 ns高重复频率电光腔倒空Nd:YVO_4激光器

报道了一种基于电光腔倒空技术的高重复频率、短脉冲Nd:YVO4激光器。该激光器以880nm连续波激光二极管作为端面抽运源,采用BBO晶体组成的普克尔盒作为电光Q开关。通过优化谐振腔,提高了激光器热稳定性和模式匹配效率。在30W的抽运功率下,获得了脉冲重复频率最高为500kHz,脉冲宽度为6ns,平均功率为10W的1064nm稳定基横模脉冲激光输出。     

深紫外固体激光系统

报道了一种利用非线性光学频率变换技术生成深紫外激光的固体激光系统.此系统采用基于CLBO晶体和频的频率变换方案,参与和频过程的两路激光分别是一台全固态声光调Q Nd:YVO;激光器输出的1064 nm近红外激光和一台灯抽运电光调Q倍频Nd:YAG激光器抽运的钛宝石激光器输出的三倍频238.7 nm紫外激光.对系统中的调Q倍频Nd:YAG激光器、钛宝石激光器、BBO三倍频模块、调Q Nd:YVO4激光器以及CLBO和频模块进行了详细描述.最后,在实验中获得了最高功率217 μW,重复频率10 Hz的195 nm深紫外激光输出.     

3.76 μm中红外激光参量振荡器

在电光调 Q,灯抽运 1.0 6 μm Nd:YAG激光抽运下 ,以 L i Nb O3 晶体为工作物质 ,利用光参量振荡技术成功实现了 3.76 μm中红外激光输出 .重复频率 5Hz时 ,单脉冲能量达 7m J.     

全固态高重复频率244 nm紫外激光器

研究了全固态脉冲运转腔外倍频244 nm深紫外激光器。采用V型谐振腔及主动调Q技术,对双二极管阵列抽运的914 nm和1047 nm基频光进行腔内和频产生488 nm高重复频率脉冲激光。在总抽运功率为44 W时,488 nm激光输出功率为527 mW。利用Ⅰ类相位匹配BBO晶体进行腔外倍频,实现了平均功率为28 mW的244 nm深紫外激光输出,重复频率为4 kHz,脉冲宽度为17.8 ns,倍频效率为5.3%。     

914 nm LD泵浦RTP电光调Q的高效率Nd:YVO4激光器

报道了一种激光二极管（LD）端面连续抽运的高重频、高光光效率电光调Q Nd:YVO4激光器。采用RbTiOPO4（RTP）晶体对作为调Q元件,通过减小热效应和模式匹配技术,实现了高效率的高重频窄脉宽1 064 nm脉冲激光输出。一方面采用低吸收系数的914 nm波长抽运Nd:YVO4晶体,使晶体内热分布均匀,从而获得高量子效率的同时减小了热效应影响。另一方面通过优化泵浦光斑半径,实现泵浦光和振荡光好的模式匹配。在重频200 kHz时,获得了最高输出功率16 W,脉宽9 ns,单脉冲能量80 J,光束质量M21.2的稳定脉冲激光,泵浦吸收功率31 W,对应的光光转化效率为51.6%。据笔者所知,这是RTP电光调Q实现的最高效率的脉冲激光器。     

高重复频率电光调Q双波长激光器

高重复频率双波长激光器在远程激光测距、光电对抗、激光通信、激光雷达等领域具有重要的应用价值。为了获得高重复频率率双波长激光输出,首先通过高重复频率驱动电光调Q技术和LD侧面泵浦技术,获得高功率、高重复频率、窄脉冲宽度的线偏振1.06μm激光输出。再利用内腔差频方式,对周期极化晶体钽酸锂(PPLT)进行差频变换,获得1.46μm和3.9μm双波段激光输出。在激光器电源抽运电流25A、调制频率10kHz时,实现40 W的1.06μm激光输出,泵浦PPLT晶体获得最高功率为2.6W的3.9μm和4.2 W的1.46μm激光,差频转换效率为17%。试验结果表明:通过高重复频率电光调Q技术和LD侧面泵浦技术,可以实现高重复频率、窄脉冲宽度1.06μm光输出,泵浦PPLT可获3.9μm和1.46μm双波长激光输出。     

LD端面抽运全固态声光调Q228.5nm深紫外激光器

采用三镜折叠V型谐振腔、声光调Q技术和三硼酸锂（LBO）晶体,对二极管端面抽运Nd∶YVO₄的914 nm基频光进行腔内倍频,实现了457 nm激光输出,利用I类相位匹配偏硼酸钡（BBO）晶体对457 nm蓝光进行腔外倍频,获得了228.5 nm深紫外激光。当抽运功率为17 W时,获得了平均功率为10 mW的228.5 nm深紫外激光输出,脉冲宽度为64.26 ns,重复频率为10 kHz。2 h内的激光输出稳定度为±2%。     

电光调Q双脉冲输出Nd:YAG全固态激光器

设计了激光二极管(LD)双端面抽运传导冷却复合Nd:YAG晶体电光调Q激光器,实现脉冲间隔可调的双Q脉冲输出。用两个光纤耦合输出的LD模块作为抽运源,偏硼酸钡(BBO)晶体作为Q开关,在一个抽运周期内两次启动Q开关,获得脉冲能量大于14mJ,脉宽小于等于18ns,脉冲间隔200～230μs可调的双Q脉冲输出,激光器重复频率50Hz,光-光转换效率达到24%。探索了用磷酸二氘钾(KD*P)调Q晶体开关实现稳定双脉冲输出的可行性,通过抑制压电环效应,消除子脉冲现象,最终获得脉冲能量约11mJ,脉宽小于等于18ns。     

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.     

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.