光阑对激光限幅器限幅效率影响的数值仿真

当激光功率超过自聚焦阈值功率时，激光光束在非线性介质中将发生自聚焦现象，光束的强度分布发生改变，本文基于激光在非线性介质自聚焦现象，设计了强激光功率限制装置，对光阑大小对限幅效应的影响进行了数值仿真研究，结果表明，一般光阑的直委径不能超过入射光束的5倍。     

Ge—APD及InGaAs／InGaAsP／InPSAGM—APD的暗电流—温度特性及其比较

1 前言 Ge-APD及InGaAs/InGaAsP/InPSAGM-APD都可以用来探测1.1～1.6μm的红外光。在长波长光纤通信系统中,需要波长为1.3～1.55μm的红外光探测器。在该光通信系统中,通过光纤入射到探测器光敏面的平均光功率一般在0.1μW～10μW范围。要探测这样微弱的光信号,不仅要求光探测器本身的噪     

高功率激光反射镜热畸变补偿结构设计与仿真

为了研究激光反射镜热畸变补偿结构的设计,在分析激光腔镜热变形行为的基础上,采用优化镜体结构,提出了一种减少入射激光光斑区域镜面热畸变的途径——热畸变自补偿激光反射镜,并与普通硅镜的热变形情况进行了比较.结果表明,当反射镜反射率为98%、入射激光功率为7kW、激光照射时间分别为2s,4s和10s时,普通硅镜镜面中心与光斑边缘处的热变形之差分别为0.167μm,0.174μm和0.172μm;而热畸变自补偿激光反射镜镜面中心与光斑边缘处的热变形之差分别为0.092μm,0.052μm和0.027μm.该研究结果对提高高能激光腔镜热效应稳定性、改善高能激光光束质量具有一定参考价值.     

无外场作用下掺甲基红向列液晶光折变特性实验研究

制备了掺杂甲基红(质量分数1%)向列液晶薄膜样品,测量了Ar+激光的透过率与样品厚度之间的关系,发现激光的偏振方向与液晶指向矢方向垂直时,透射率最大。选择Ar+激光作为写入光,重点利用二波耦合实验测量了一阶衍射效率随样品厚度、入射光夹角、两束入射光光强、两束入射光光强比的变化关系,实验发现当液晶薄膜样品厚度为32μm,两束入射光夹角为2°,两束入射光光强分别为80mW/cm2且光强比为1∶1时具有最佳的全息存储实验条件。     

飞秒激光刻写的10 kW级啁啾倾斜光纤布拉格光栅

啁啾倾斜光纤布拉格光栅（CTFBG）是高功率光纤激光系统中抑制受激拉曼散射（SRS）的关键器件。使用飞秒激光在50μm/400μm光纤上研制了可承受10 kW激光功率的CTFBG。CTFBG插入损耗为0.03 dB,制冷后的功率温升系数仅为2.4℃/kW,验证了飞秒激光刻写的CTFBG具有优异的功率承受能力。     

国产25μm/400μm啁啾倾斜光纤光栅传输功率突破4kW

啁啾倾斜光纤光栅(CTFBG)在高功率光纤激光受激拉曼散射抑制中有重要的应用。在25μm/400μm光纤上研制了可承受4.35kW激光功率的CTFBG,这是目前国内外已报道的最高功率水平。CTFBG的插入损耗小于0.3dB,最高功率下的温升仅为7.5℃,温升系数约为1.72℃/kW,表明其具有承受更高激光功率的能力。     

全息激光防护薄膜的防护效果试验

研制成功了全息激光防护薄膜。本文报道了全息激光防护薄膜对强功率激光的防护效果试验。试验表明:薄膜对0.53μm波长激光的平均光密度D为4.11,有效防护角为15°,抗激光破坏能力强;在60mJ激光入射能量内,薄膜对兔眼的激光防护效果显着,眼损伤的发生率为百分之零。     

向列相液晶激光器件侧面辐射谱研究

研究了向列相液晶激光器件侧面激光辐射谱,并深入分析了激光辐射机制。分别制备了传统液晶盒和引入SU-8光栅结构的两种器件,并注入向列相液晶TEB30A和激光染料PM597的混合物。利用Nd:YAG固体脉冲激光器倍频出的532 nm激光作为泵浦源正面入射器件,侧面探测激光辐射谱。在传统液晶盒器件侧面,测得575～600 nm范围的随机激光辐射谱。而具有周期100μm和8μm的SU-8光栅结构器件侧面,获得了多波长激光辐射谱。随着泵浦能量增大,最高强度激光辐射峰波长位置出现在583～585 nm和588～592 nm附近,FWHM约0.3 nm。基于光波导理论结合器件结构分析得出,在传统液晶盒中引入SU-8光栅结构增强了液晶器件的光波导效应,是获得多波长激光辐射谱的主要原因。     

一种伽码激光的实现方式

提出了波长为λi的入射激光与速度为v0、通过波长为λw周期磁场的电子束背散射产生波长λf激光的方案。只要v0足够大,就有λf远小于λi。扭摆磁铁覆盖有缝隙的超导片后,λw虽不变,但有效背散射区纵向长度s能显著减小。足够强的入射激光也能使s显著减小。与电子束平行的激光谐振腔能产生强度足够大的入射激光。这样,波长λf激光就能实现。即使出射激光的光子数少于入射激光光子数,出射激光的功率仍可以大于入射激光的功率。     

液晶二元光栅用于激光方位探测与跟瞄

提出了基于液晶二元光栅的用于激光方位探测与跟瞄系统的构架和计算模型,并提出使调制以后的激光束始终指向受控对象,并向系统报告受控对象方位的技术方案。通过采用电控液晶二元光栅的对入射激光辐射偏转,使之聚焦于二象限探测器中心的方法可以获得激光源的方位,而探测器上的信号可被用于分析入射激光辐射的调制频率、码型等信息。由于液晶二元光栅的光程分布可以被任意写入,人们可以很快验证衍射光学元件的设计,而液晶二元光栅的可控特性可以实现常规衍射光学元件不可能实现的功能,从而在激光束方位的探测和跟瞄、大气湍流的校正等各个方面都有潜在的应用。     

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.     

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.     

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.     

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.