光泵NH3分子亚毫米波频谱特性的理论计算

本文从密度矩阵方程出发,分别采用三能级和多组独立三能级迭加的近似方法对光泵NH_3分子亚毫米激光器的输出光强进行了理论研究.同时根据NH_3分子能级结构对TEA-CO_2激光器的10R(6)谱线泵浦NH_3分子亚毫米波频谱特性进行了数值计算,理论计算结果与实验符合较好.     

基于D2O的光抽运腔式太赫兹波激光谱线竞争

从半经典密度矩阵理论出发,建立了光抽运太赫兹波谱线竞争的双三能级分子系统模型,理论推导了抽运信号吸收系数以及太赫兹波信号增益系数的数学表达式,采用迭代法数值计算了CO2激光-9P(32)抽运重水(D2O)气体分子腔式太赫兹激光66μm和116μm两条谱线之间的竞争。给出了抽运功率、工作气压及激光腔长等工作条件下谱线竞争的一般规律。     

缓冲气体对光泵亚毫米波激光作用的定量解释

建立缓冲气体对光泵亚毫米波激光作用的理论模型,通过量子力学理论推导了缓冲气体退激活几率,从而使缓冲气体的作用能够定量进行计算．实验上对CO2-9(R30)泵浦NH3分子67．2um谱线作了测量,实验结果与理论计算吻合得较好．这一工作对寻找光泵小型腔式亚毫米波气体激光器的高效缓冲气体有指导意义．     

Mollow谱线与电磁诱导透明和吸收的叠加

对双耦合场作用下的Λ型三能级系统的透明和吸收特性进行了理论研究。在二能级系统中,强耦合场和探测场同时作用于激发态能级和基态能级之间,探测吸收曲线上出现Mollow谱线。在激发态能级和基态的另一精细结构能级之间引入另一个耦合场,构成Λ型三能级系统。在这个双耦合Λ型三能级系统中,出现了一些新的量子相干现象。结果表明,探测吸收谱线中不仅有Mollow现象,还出现了电磁诱导透明(EIT)和电磁诱导吸收(EIA)。分析了EIT和EIA的位置随双耦合场参数的变化规律,并用缀饰态理论做出了解释。     

连续激光泵浦重水气体分子产生THz激光辐射的阈值分析

利用连续运转二氧化碳激光器的9R(22) 输出谱线泵浦重水气体(D2O)分子可以产生波长为385微米,频率为0.78THz的连续激光辐射输出,采用半经典理论分析方法并结合三能级系统模型可以对此激光过程进行有效的分析,通过合理的近似简化了求解过程,得到了光场中太赫兹激光信号增益系数Gs和泵浦光信号吸收系数Gp的解析表达式,通过对求解结果的分析,计算出产生THz激光振荡的泵浦阈值条件为6.24×10-3W/mm2,一般情况下,在泵浦激光输出光斑面积为0.25mm2时,要求泵浦激光谱线的输出功率达到1.6mW以上才能形成THz激光辐射。     

高效率连续波运转的激光二极管端面抽运914 nm Nd:YVO4激光器

利用激光二极管(LD)抽运Nd∶YVO4晶体产生914 nm谱线振荡,再通过腔内倍频技术获得457 nm激光输出,是获得大功率蓝光激光器的一条重要的技术路线,因而实现高效率运转的914 nm激光输出则是方案的关键。报道了激光二极管端面抽运Nd∶YVO4晶体、连续波运转的大功率914 nm准三能级激光器,方案中采用掺杂原子数分数为0.1%的低掺杂Nd∶YVO4晶体,有效地降低了热效应的影响,并通过准三能级理论模型的模拟计算选择了最佳晶体长度;通过对腔镜介质膜参数的适当控制,有效地抑制了波长为1064 nm和1342 nm的高增益谱线。实验中,914 nm激光器的阈值抽运功率仅为8.5 W,在31 W的抽运功率下914 nm激光输出功率高达7.2 W,激光器的斜率效率为32%,光-光转换效率为23.2%。     

液氮下激光二极管端泵Nd:GdVO4 912 nm激光器研究

对准三能级系统进行了理论分析,指出了产生4F3/2→4I9/2 912nm谱线跃迁的阈值条件,给出了影响激光输出的因素.首次在液氮温度(78K)下实现了激光二极管端泵Nd:GdVO4晶体912nm激光振荡,在泵浦功率为12.5 W时,获得了1.1 W的912 nm连续激光输出,对吸收泵浦光功率的斜坡效率为18%,并估算了低温下912 nm的受激发射截面,观察到了912 nm谱线随温度升高而红移的现象.     

金绿宝石的高增益激光特性

本文所报道的以纯电子三能级激光方式工作的金绿宝石Q开关特性完全类似于红宝石激光作用。由工作在680.4毫微米高增益R_1谱线的金绿宝石激光器获得20毫微秒Q开关脉冲,能量为0.5焦耳/脉冲。金绿宝石(BeAl_2O_4:Cr~(3+))与斜方橄榄石是同构形(空间群Pnma),在室温由700～800毫微米以四能级电子振动方式产生受激光。BeAl_2O_4和Al_2O_3中Cr~(3+)的光谱特性相对R谱线工作来说性质上相似。金绿宝石抽运带,强度近似于与红宝石等值,峰值在(?)410和(?)590毫微米,R谱线分别出现在R_2为678.5和R_1为680.4毫微米。斜方结构导致三种性质不同的偏振。R_1主谱线偏振E∥b,发射截面为3×10~(-19)厘米~2,约为红宝石的10倍,为Nd:YAG的1/3。这种     

亚毫米波气体激光器及其应用

严格地说,亚毫米波是指波长从0.1mm至1mm的电磁波,而这里是指波长从10μm至10mm的电磁波。亚毫米波激光器可以分成固定波长和波长可调二大类。属于前者的是亚毫米波气体激光器。亚毫米波气体激光器按激励方式可分为放电和光激励二种。气体激光器在波长0.1μm至3mm内共有500～6000根谱线,而目前亚毫米波激光器波长占它的20％之多。目前,亚毫米波激光器不再是一种小功率激光器,预计它的输出功率可达千兆瓦级。近年来,由于在能源上的应用使亚毫米波激光器越来越受到重视。利用自由电子流作激光工作物质的所谓自     

亚毫米波激光辐射对水稻生长的影响

生物活体分子内存在大约10~(11)～10~(12)Hz 纵向电振动模,这一频率范围正是光泵远红外激光器的工作谱区。基于该理论推断,进行了亚毫米波激光辐射水稻种子的实验,文中介绍经亚毫米波激光辐照后的稻种栽培种植的初步试验结果。仅以此作为光泵远红外激光器的应用尝试。     

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.     

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.     

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.     

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.     

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