基于AlxNy绝缘介质膜的新型窗口大功率半导体激光器

提升半导体激光器的腔面抗光学灾变(COD)损伤的能力,改善半导体激光器的工作特性,一直是大功率半导体激光器器件工艺研究的难点.基于薄膜应力使基底半导体材料带隙变化的原理,采用直流磁控溅射方法在不同条件下溅射生成不同内应力的AlxNy绝缘介质膜.通过研究大功率半导体激光器腔面退化机理,借助AlxNy等应力膜设计制作了一种新型非吸收透明窗口结构的宽条形半导体激光器,使器件平均最大输出功率提高46.5%,垂直发散角达到21°,水平发散角达到6.1°,2000 h加速老化试验,其千小时退化速率小于0.091%.     

基于虚拟仪器的自动测试系统研究

随着自动测试设备由台式仪器向模块化仪器方向的发展,自动测试系统正在从专用型向通用型方向转变,但是仪器互换性和测试程序的可移植性问题限制了它的发展.近年来,虚拟仪器在自动测试中的应用越来越广泛,运用虚拟仪器可以共享硬件和软件资源,并且方便、快速的组建各种自动测试系统.本文描述了自动测试系统的基本概念,系统构成,工作原理;分析了自动测试系统的发展趋势和国内外的研究现状,虚拟仪器的发展概况以及虚拟仪器对自动测试系统的影响,故障诊断与故障定位;并且着重介绍了基于虚拟仪器的自动测试系统软硬件的构成,及其它们的工作原理,测试工作等,叙述了自动测试系统的功能自检测.     

An Improved Architecture of Sixth Subharmonic Mixers in E-Band

An improved architecture of sixth subharmonic mixers is proposed in this paper. In order to meet the need of low conversion loss, antiparallel diodes are selected and the length of four open/shorted microstrip stubs at both sides of the antiparallel diodes are carefully designed. For any important idle frequency components which can’t be reused by the four stubs, reactive terminations are presented by adjusting the length of main RF and LO microstrip. The tested results indicate the lowest conversion loss is 26.1 dB at the radio frequency of 72 GHz, with fixed LO at 12 GHz. The proposed circuit architecture is suitable for the implementation of subharmonic mixers in E-band as well as other millimeter and submillimeter-wave regions where high quality and high frequency LOs are difficult to realize.     

A Novel Circuit Architecture for High Performance of High-order Subharmonic Mixers

A novel circuit architecture for high performance of high-order subharmonic (SH) mixers is proposed in this paper. According to the specified harmonic mixing order, one or more mixer diodes sub-arrays and corresponding power divider as well as phase shift network for RF and LO signals are arranged in the circuit. This proposed SH mixer circuit has improved conversion loss, wide dynamic range and high port isolation for high-order SH mixers. By phase cancellation of idle frequencies, the proposed SH mixer circuit can eliminate complicated design procedure of idle frequency circuits; by phase cancellation of leakage LO power to RF and IF port, and leakage RF power to LO port, the mixer circuit can get high port isolation in LO-IF/RF and RF-LO. The increased antiparallel diode pairs in each sub-array will also lead to well performance by lowering effective series resistance. The proposed SH mixer circuit can be easily realized with power divider and phase shift network for RF and LO signals.     

基于单片机控制的步进电机曲线运动模型的设计

步进电机是将电信号转换成角位移或线位移的装置,由于步进电机在速度和位置上的控制优势,使得由步进电机控制的切割机床等生产机床能够更加准确和便捷的完成任务,使得生产能够更快更好的满足市场的需求。单片机做为一种嵌入式的控制芯片,要比PLC更加高效、易懂,也更加的节约成本,使得操作更加简单。本文采用89C51单片机完成对步进电机的控制,使两个步进电机控制的切割点在一个固定的平面内做曲线运动,通过光电编码器反馈角位移信号给单片机控制端,并分析步进电机的加减速曲线控制,设计了基于单片机的步进电机平面切割模型。     

欧洲主要电信运营商专线资费的演变

欧洲主要电信运营商所处国度的经济和人口布局情况不同，竞争环境也有差别，在专线资费方面的做法也有许多不同之处。考虑到地区之间竞争的差异。目前多数国家都取消了地区交叉补贴的做法，但还有一部分国家仍然坚持统一费率。在资费方面的基本促销手段为接合同年限和用户的支出额打折。从2000年到2003年资费演变的基本情况是；接入费扣2Mbit／s以下较低速率的专线租费保持平稳略有下降，较高速率专线的租费则有较大的下调幅虚。     

提高硫化铅红外探测器的探测率和可靠性的有效途径

本文通过对不同结构的硫化铅红外探测器的剖析和性能优劣对比,说明了新型场镜—硫化铅组合结构是提高硫化铅红外探测器的探测率和可靠性的有效途径。     

周期性动态热效应光栅的研究

为使激光诱导动态光栅产生在空间上可分辨的高效率衍射光，光栅介质必须足够薄以满足光栅条件，但动态光栅自衍射效率却又随介质厚度的增加而增加，我们提出用相位匹配的周期性薄光栅组可解决这一矛盾，并在实验上用周期性热效应光栅对理论进行了验证。