Fabrication of GaN-based LEDs with 22° undercut sidewalls by inductively coupled plasma reactive ion etching＊

We use a simple and controllable method to fabricate GaN-based light-emitting diodes （LEDs） with 22° undercut sidewalls by the successful implementation of the inductively coupled plasma reactive ion etching （ICP-RIE）. Our exper- iment results show that the output powers of the LEDs with 22° undercut sidewalls are 34.8 rnW under a 20-mA current injection, 6.75% higher than 32.6 mW, the output powers of the conventional LEDs under the same current injection.     

Influence of Si doping on the structural and optical properties of InGaN epilayers

Influences of the Si doping on the structural and optical properties of the InGaN epilayers are investigated in detail by means of high-resolution X-ray diffraction （HRXRD）, photolumimescence （PL）, scanning electron microscope （SEM）, and atomic force microscopy （AFM）. It is found that the Si doping may improve the surface morphology and crystal quality of the InGaN film and meanwhile it can also enhance the emission efficiency by increasing the electron concentration in the InGaN and suppressing tile formation of V-defects, which act as nonradiative recombination centers in the InGaN, and it is proposed that the former plays a more important role in enhancing the emission efficiency in the InGaN.     

Study of BESⅢ MUC offine software with cosmic-ray data

Cosmic-ray data of 90 M events have been collected and used for calibration,alignment as well as detector tuning. A special tracking algorithm for the BESⅢ muon counter is developed and verified with Monte-Carlo simulation and then further confirmed with the cosmic-ray data. The obtained strip resolutions are in good agreement with the design values. A new alignment approach for the BESⅢ muon counter is confirmed with the cosmic-ray data and proposed to be used in future analysis of experimental data.     

基于LD激发荧光粉白光光源的窄光束照明光学系统设计

蓝光半导体激光器激发荧光粉产生白光光源技术发展迅速,但由于大功率蓝光半导体激光器在快轴、慢轴方向的光场分布差别较大,使得日前激光照明整体光学性能仍旧较差,难以实现大规模推广应用。针对该问题,设计了一款高质量激光照明光学系统,基于蒙特卡洛光线追踪理论,对激光光束进行准直调控、均匀光斑整形以及对荧光片进行设计,使得整体光源模块各元件得到最佳整合,最终实现了窄光束激光照明。仿真结果表明:激光光源的光收集率达98.3%,激光光斑的不均匀度为1.7%,白光均匀度为98%,光斑是出射准直角为1.6°的方形窄光束白光光斑。     

High-power ultraviolet 278-nm laser from fourth-harmonic generation of an Nd:YAG amplifier in CsB_3O_5 crystal

We report on the experimental investigation and theoretical analysis of a nanosecond pulse high power ultraviolet(UV) 278 nm laser by fourth-harmonic generation(FHG) of a 1112-nm Nd:YAG amplifier in LiB_3O_5(LBO) and CsB_3O_5(CBO) crystals. The UV laser delivers a maximum average power of 10.3 W at 278 nm with peak power of 36.8 k W under input pump power of 41 W at 556 nm. This is, to the best of our knowledge, the highest output power at the specific UV wavelength of 278 nm. We also performed the theoretical investigation on the FHG with a model in the Gaussian approximation of both spatial and temporal profiles, especially accounting for the two-photon absorption effect in CBO crystal for the first time. The average output power, pulse width, and beam spatial distribution of the UV laser were simulated. The theoretical calculations are in close agreement with the experimental results.     

Technique for Monolithic Fabrication of Microlens Arrays Integrated with Infrared CCD

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｉｎｆｒａｒｅｄｃｈａｒｇｅｃｏｕｐｌｅｄｄｅｖｉｃｅ(ＩＲＣＣＤ )ｓｅｎｓｉｔｉｖｅｆｒｏｍ 3ｔｏ 5μｍｈａｓｎｕｍｅｒｏｕｓａｐｐｌｉｃａｔｉｏｎｓｉｎｂｏｔｈｍｉｌｉｔａｒｙａｎｄｃｉｖｉｌｉｎｄｕｓｔｒｉｅｓ[1] .Ｔｏ ｇｅｔｌａｒｇｅａｒｒａｙＩＲＣＣＤ ,ｒｅｃｅｎｔｔｒｅｎｄｓｉｎＩＲＣＣＤｔｅｃｈｎｏｌｏｇｙａｒｅｔｏｒｅｄｕｃｅｂｏｔｈ ｐｉｘｅｌｓｉｚｅａｎｄｔｈｅａｃｔｉｖｅａｒｅａ .Ｗｈｅｒｅａｓｔｈｅｆｏｒｍｅｒｉｎｃｒｅａｓｅｓａｒｒａ…     

Mixing MC events in a reactor neutrino experiment

In reactor neutrino experiments, the analysis of time correlations between different physical events is an important task. Such analysis can help to understand the physical mechanisms of the signal and background events as well as the details of event selection and background estimation. This study investigates a "sampling and mixing" method used for producing large MC data samples for the Daya Bay reactor neutrino experiment. We designed a simple, generic mixing algorithm and generated large MC data samples for physics analysis from several samples according to their respective event rates. Basic plots based on the mixed data are shown.     

运用线性约束条件解题两例

r|112、|.、r||zlwe|、由得例’已知’数二，一{ y簇x，x Zy毛4，则y)一2，s一扩 犷 Zx一Zy 2的最小值是( 9 tZ气)二二勺(B)2(C)3 ). (D)涯f(0)~Zb>0，f(l)=a Zb 1<0，f(2)一Za Zb 4>0，b)0，a Zb十1<0，a b 2>0.解画出满足不等式的可行域如图1所示. S一xZ 少， Zx一Zy 2~(x 1)’ (少一1)2的.y巍广”满热戮握袅‘4凛蘸瓢】瓢黔画出满足上述不等式组的平面区域如图2所示.解方程组图1 { a Zb l=0，a十b十2一O，几何意义是表示点A(一1，1)与可行域内的点的距离的平方，丫百的最小值为点A到直线y~x的距离福，从而S的最小值为2，故选(B…     

问题170——关于等比数列的“分段和”：Sk，S2k-Sk，S3k-S2k，…组成的数列

该问题来稿十分踊跃，至本刊截稿时，共收稿29篇（看来还有来稿之势），均认为解法1结果正确，解法2结果错误．来稿前6名的作者是：南通高等师范学校王兴东，湖南省邵东县金龙南路95号黄旭明，内蒙李国梅，河南省上蔡一高王安寓，江苏省镇江中学陆建根，安徽省淮南市第三中学代银、南佳水（合稿）．     

矩底拱面状微透镜阵列的氩离子束刻蚀 

在ZrO2、InP、Si及SiO2即融凝石英衬底上用氩离子束刻蚀制作面阵矩底拱面状微透镜阵列,给出了氩离子束在不同的入射角度下刻蚀器件的速率与离子束能量之间的关系。实验表明,用国产BP212 紫外正型光刻胶制作的光致抗蚀剂掩膜图形在经过优化的工艺条件下可以通过氩离子束刻蚀将预定图形转移到衬底材料中。