Nd∶YAG/Cr∶YAG键合晶体的355nm激光器

报道了一台基于Nd∶YAG/Cr∶YAG键合晶体的全固态355nm紫外(UV)激光器的设计及实验结果。采用平-平腔结构获得高峰值功率、小束腰的1064nm基频光。在谐振腔外,未聚焦的1064nm基频光经KTP晶体倍频产生532nm波长激光,二者再经LBO晶体和频获得355nm紫外激光输出。实验中发现尽管Nd∶YAG与Cr∶YAG都是各向同性晶体,但在特定情况下输出的1064nm基频光具有近似线偏振的特性,此特性可以有效地增加二次谐波产生(SHG)时基频光的利用率,从而提高整台激光器的转换效率。而基频光的谱线宽度及发散角也影响二次谐波及三次谐波产生(THG)的转换效率,需使其尽量在晶体的允许带宽及允许角范围以内。综合这几点因素,对激光谐振腔进行了仔细设计。当激光二极管(LD)抽运功率为8W,激光器运行稳定时,基频光峰值功率达28kW,最终获得平均功率为124mW的355nm紫外激光。     

热近非稳腔高重频双波长复合输出激光器研究

1064 nm/532 nm双波长固态激光器在多个领域应用广泛。针对目前该类激光器分光路可切换输出研究较多,而复合输出研究缺乏的现状,通过建立含热透镜的等价谐振腔模型,结合谐振腔稳定性和“热近非稳谐振腔”理论确定了最佳腔长,利用软件仿真分析了倍频晶体的长度、输出镜基频透过率、调Q频率的大小对复合输出的影响,根据双路激光干扰的实际需求,确定了最佳复合输出参数,从而完成了一台1064 nm/532 nm高重频双波长复合输出激光器的设计。实验表明,KTP晶体长度选为12 mm,输出镜基频透过率选为15%,调Q频率选为50 kHz时,在最大泵浦功率下,基频光输出的平均功率为28.82 W,倍频光的输出的平均功率为2.23 W。测量得到的激光近场发散角与光斑半径的乘积近似等于同样位置处基模高斯光束发散角与光斑半径的乘积,这说明所设计的激光器在最大泵浦功率条件下是以近似基模的方式运转,具有较好的光束质量。     

Nd:YAG/Cr:YAG键合晶体的355 nm激光器

报道了一台基于Nd:YAG/Cr:YAG键合晶体的全固态355 nm紫外(UV)激光器的设计及实验结果.采用平-平腔结构获得高峰值功率、小束腰的1064 nm基频光.在谐振腔外,未聚焦的1064 nm基频光经KTP晶体倍频产生532 nm波长激光,二者再经LBO晶体和频获得355 nm紫外激光输出.实验中发现尽管Nd:YAG与Cr:YAG都是各向同性晶体,但在特定情况下输出的1064 nm基频光具有近似线偏振的特性,此特性可以有效地增加二次谐波产生(SHG)时基频光的利用率,从而提高整台激光器的转换效率.而基频光的谱线宽度及发散角也影响二次谐波及三次谐波产生(THG)的转换效率,需使其尽量在晶体的允许带宽及允许角范围以内.综合这几点因素,对激光谐振腔进行了仔细设计.当激光二极管(LD)抽运功率为8 W,激光器运行稳定时,基频光峰值功率达28 kW,最终获得平均功率为124 mW的355 nm紫外激光.     

计量用脉冲Nd：YAG倍频激光器及其电源

介绍了脉冲Nd:YAG倍频激光器双波长（1064／532nm）3种输出的激光光路。1064nm输出的动静比可达0.40；KTP晶体外腔倍频效率可达0.50。介绍了稳定可靠的调Q电路、逻辑控制电路和开关电源的主电路及其参数计算。     

大能量窄脉宽高平均功率绿光激光器

研制了在大能量窄脉宽情况下实现高平均功率输出的绿光激光系统。利用激光二极管抽运Nd∶YAG晶体,采用RTP晶体电光调Q和主振荡功率放大的功率分摊技术,实现大能量窄脉宽高重复频率532 nm绿光激光输出。输出基频光波长1064 nm,脉冲平均能量213 mJ,工作频率100 Hz,光-光转换效率12%。采用Ⅱ类相位匹配高抗灰迹KTP晶体腔外倍频,输出绿光波长532 nm,脉冲平均能量127 mJ,工作频率100 Hz,脉冲宽度7.2 ns,光束质量20mm.mrad,532 nm插头效率2.1%。     

LD端面泵浦千赫兹多波长激光器

报道了一台用于大气探测激光雷达系统的LD脉冲端面泵浦Nd∶YAG激光晶体的腔外倍频千赫兹多波长激光器.采用紧凑介稳腔设计和电光调Q方式,获得具有高动静比的1064 nm基频光脉冲输出.腔外采用Ⅰ类相位匹配LBO晶体倍频,Ⅱ类相位匹配LBO晶体和频,实现了355 nm和频光输出,同时对355 nm和频光单脉冲能量的影响因素进行了理论分析和实验研究.当倍频转换效率为53％时,获得重复频率为1 kHz的三波长激光分束输出,对应的单脉冲能量分别为1.18 mJ@1064 nm、1.06 mJ@532 nm、0.73 mJ@355 nm;脉冲宽度分别为3.49 ns@1064 nm、3.42 ns@532 nm、3.02 ns@355 nm;光束质量因子分别为Mx2=1.70、Mx2=1.75@1064 nm,Mx2=1.57、Mx2=1.41@532 nm,Mx2=1.51、Mx2=1.38@355 nm.     

基于电光调Q1064nm/532nm/570nm三波长固体激光器

为了提升激光技术在色素性疾病治疗等生物医学应用效果, 研制了一种1064nm, 532nm, 570nm三波长激光器。采用电光调Q Nd:YAG激光器获得最窄脉宽为11ns的1064nm脉冲激光输出, 使用磷酸氧钛钾(KTP)非线性晶体对基频光腔外倍频获得532nm激光输出; 以固体染料块为激光增益介质, 倍频光为抽运光, 可获得中心波长为570nm的黄光输出, 光光转换效率为61.3%。结果表明, 通过改变氙灯注入电压, 可以调节1064nm激光脉冲输出特性; 增加固体染料激光器腔长, 可以调节染料激光输出光谱特性。该研究结果对激光器灵活应用具有重要意义。     

（1064／1319，532／659nm）Nd：YAG激光治疗仪的实验研究

叙述了激光治疗仪双波长（1064/1319nm）输出的最佳方案及其性能指标：介绍了双波长输出的CW-Nd:YAG激光器参数的确定及其倍频实验，提出了用Ti:Mgo:LiNbo3晶体倍频的4波长Nd:YAG激光器5种输出的可行性方案。     

LD端面泵浦355 nm紫外激光器

采用大功率激光二极管模块光纤耦合端面泵浦Nd∶YVO4晶体,声光调Q,腔外三倍频方式实现355 nm紫外激光输出。通过计算设计了高效稳定基频谐振腔,在腔外采用LBOⅠ类相位匹配和LBOⅡ类相位匹配的方式倍频与和频,并采用4 f系统对1064 nm基频光和532 nm倍频光进行聚焦,减小了球差效应对光束的影响以提高和频效率。在泵浦功率32.3 W,得到15.9 W 1064 nm连续基频激光输出,光光效率49%。在20 kHz调制频率下,得到1.45 W355 nm紫外激光输出。通过Spiricon光束质量分析仪进行测试,在大功率输出时,紫外激光光束质量因子M2x=1.6,M2y=1.56。     

LD抽运Nd:YVO4连续3波长激光器

报道了一种利用激光二极管(LD)端面抽运Nd:YVO4激光晶体,通过硼酸铋(BIBO)晶体的腔内和频(SFM)与倍频(SHG),实现3个二次谐波连续激光同时输出的3波长激光器.利用Nd:YVO4晶体的两条发射谱线(分别为1064 nm和1084 nm)作为基频光,并选掸长度为1.5 mm,Ⅰ类临界相位匹配方式切割(对于1064 nm倍频)的BIBO作为非线性晶体,通过调节BIBO晶体对3个非线性过程(1064 nm倍频,1084 nm倍频及1064 nm与1084 nm和频)的相位因子,即非线性过程的转换效率,使激光器同时获得了两个倍频光和一个和频光,即3个波长:532 nm,537 nm和542 nm激光输出.实验结果表明当两个基频光波长相差较小时,采用相位允许角小的非线性晶体同时进行腔内和频与倍频是获得多波长固体激光器的一种实用方法.     

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.     

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.     

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.     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks