套管辅助法测量异型预制棒折射率分布

基于光束扫描法的光纤预制棒折射率测试仪主要适用于直径和长度在一定范围内的圆柱形样品折射率分布的测试。提出一种套管辅助法可实现更短长度、更细直径和变直径样品的折射率测试。该方法将待测样品居中放置于一个尺寸符合测试要求的圆柱形套管内,并在套管内注入折射率匹配油,使其没过待测样品后按常规步骤进行测试。对比实验结果表明,套管辅助法与直接测量法的偏差与仪器的测量误差相当。采用套管法,获得了预制棒拉丝终止后变径区不同位置折射率的径向分布,可为拉丝过程的研究提供参考。     

X射线自由电子激光试验装置

X射线自由电子激光试验装置(以下简称"SXFEL试验装置")是中国第一台X射线相干光源,其输出波长小于9 nm.这台基于0.84 GeV直线加速器、以掌握装置相关技术和实验演示种子型自由电子激光(FEL)级联与短波长回声型FEL为主要目标的自由电子激光装置,于2020年11月通过国家验收.本文将介绍SXFEL试验装置的...     

One-dimensional atom laser in microgravity

Using coupled Gross-Pitaevksii (GP) equations, we simulate the output of one-dimensional pulsed atom laser in space station. We get two atom laser pulses propagating in opposite directions with one pulsed RF coupling. Compared with atom laser under gravity, the laser pulse in microgravity shows much slower moving speed, which is suitable to be used for long-term investigations. We also simulate the output flux at different coupling strengths.     

近用镜增加度的计算

本文介绍计算近用镜增加度的公式，不是只根据年龄，而是根据眼睛的远点及调节幅度。由此计算的散光眼的近用镜增加度不是球面而是球柱面的，可将眼睛视近时的散光完全矫正。     

数字音响系统(三)

从DAT到DCC，家用音响系统的数字化在技术和经济上有了突破．在数字录音放音系统的发展过程中，DCC的出现解决了高质量和低成本的矛盾，因此必将取代目前广泛流行的盒式磁带录音机．DCC的最大特点是与现有模拟盒式磁带的兼容性，即DCC录音机上既可以放DCC带也可以放模拟盒式磁带，并且在国际范围内达成了禁止复制的连续转录管理系统，解决了多次复制涉及的音乐软件版权问题．四、数字式磁带系统1．我字音频盒带录音机数字录音机的发展经历了两个阶段．第一阶段主要研究声频信号数字化技术，而记录器则采用录象机，把处理后的数字声…     

A novel 852-nm tunable fiber laser

We report a novel fiber laser operating at 850-nm band by using semiconductor optical amplifier and fiber grating. The laser system is stable, compact, and the operating wavelength can be tuned continuously from about 851 to 854 nm for Cs atomic clock system by stretching the fiber grating. An output power up to 20 mW is obtained with a signal-to-background ratio beyond 20 dB.     

高频区具有大带隙的二维像素型光子晶体结构

针对方块像素组成的二维光子晶体，传统平面波展开法可经修正使之收敛速度大大提高。采用快速算法，在高频区域找到了一种具有稳定的较大绝对禁带宽度的GaAs光子晶体结构，绝对禁带宽度为0．0995ωc(ωc-2π／α，α为晶格常量，c为光速)，中心频率为1．2625ω。     

A study on the decay of ^72As

The excited states of the ⁷²Ge nucleus were investigated in radioactive decay of ⁷²As. Three new transitions with 1996.58, 2125.59 and 2255.49keV have been found for the first time. One γ-ray with 912.09keV has been placed in the decay scheme for the first time, and the placement of 1938.88, 2116.79, 2785.59, 2833.03, 2950.69 and 3338.00keV γ-rays are confirmed again in the present work. One new level at 2027.72keV excitation energy is proposed. The level scheme was established and for a number of levels spin-parity assignments are suggested on the basis of logft values and γ-branching ratios.     

2.1μm Ho：LuAG ceramic laser intracavity pumped by a diode-pumped Tm：YAG laser

We report a compact Ho：LuAG ceramic laser intracavity pumped by a diode-pumped Tm：YAG ceramic laser. The laser oscillation is accomplished by using a common linear cavity configuration containing Tm：YAG and Ho：LuAG ceramics. The 1.0 at.% Ho：LuAG ceramic laser yields 1.15 W of maximum output simultaneously at 2094 and 2100 nm with a beam quality factor of M2-2.8.     

Belle实验?(5S)数据中新类底偶素态的寻找

Belle实验组利用在?(5S)共振峰上采集的大数据样本,对e+e－→π+π－?(nS)和π+π－hb (mP)(n=1,2,3,m=1,2)过程进行了研究,在π±?(nS)和π±hb(mP)的系统中,同时观测到了两个新的带电类底偶素结构——Zb(10610)和Zb(10650)。它们衰变到底偶素末态,同时还带有电荷,所以它们的组成成份中至少含有4个夸克。最近,对e+e－→π+π－π0γ?(1S)过程也进行了研究,在ω?(1S)系统中对类X(3872)的底偶素态Xb进行了寻找。