杨氏模量的实验研究

1实验装置 传统静态法对杨氏模量测量[1]的缺点是载荷大、含有弛豫过程,不能真实地反映材料内部结构的变化.在脆性材料和不同温度下的杨氏模量的测量中都会受到限制.     

采用环形再生腔结构的飞秒激光啁啾脉冲放大研究

采用环形再生腔结构的啁啾脉冲放大技术方案, 在重复频率100 Hz,单脉冲能量33.1 mJ的532 nm激光抽运下, 从钛宝石激光中获得了单脉冲能量9.84 mJ的放大输出, 对应的斜效率达33.1%.在重复频率10 Hz的情况下, 同样获得了单脉冲能量为9.64 mJ, 对应斜效率达36.8%的高效率放大结果. 通过色散补偿压缩该啁啾激光脉冲后的单脉冲能量为6.36 mJ, 脉冲宽度为59.7 fs. 测量结果表明典型的能量不稳定度为1.85%. 关键词： 啁啾脉冲放大 再生放大 飞秒激光 环形腔     

Effective SNR improvement using a high-power pulsed pump in an ytterbium-doped fiber amplifier

A high-power pulsed pump method is proposed to obtain a high-energy output with an improved signal- to-noise ratio （SNR） during pulse amplification. Based on numerical analysis, the ytterbium-doped fiber amplifiers are compared under different pumping conditions. At the same signal gain, the output using the high-power pulsed pump shows great SNR improvement and reduced output signal distortion, compared with a continuous-wave pump and a low-power pulsed pump. By adjusting the pump parameters, the amplifier can achieve the optimal output SNR without sacrificing the signal gain. We believe that the high-power pulsed pump scheme is very suitable for the high-energy nanosecond pulse amplification, which has a high SNR requirement.     

Limit on the electron neutrino magnetic moment from the kuo-sheng reactor neutrino experiment

A search of neutrino magnetic moment was carried out at the Kuo-Sheng Nuclear Power Station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 kg(-1) keV(-1) day(-1) at 12-60 keV were achieved. Based on 4712 and 1250 h of reactor ON and OFF data, respectively, the limit on the neutrino magnetic moment of mu(nu;(e))<1.3x10(-10)mu(B) at 90% confidence level was derived. An indirect bound of the nu;(e) radiative lifetime of m(3)(nu)tau(nu)>2.8x10(18) eV(3) s can be inferred.     

以ZnO为电子传输层PPV的发光

以Ⅱ-Ⅵ族无机半导体ZnO为电子传输层,PPV为空穴传输层和发光层,得到的电致发光器件比单层PPV器件的发光亮度和效率都高.器件结构为ITO/PPV/ZnO/Al的电致发光光谱同单层PPV器件的光谱基本相同,但是启亮电压明显比单层器件低,最大亮度大约比单层器件高6倍左右,同时工作电流也比单层器件小.通过PPV层自吸收现象可判断出发光区域在PPV/ZnO界面处.电流-电压曲线表明,这种器件具有空间电荷限制电流特性,即J∝Vn,这里n大约为2,这器件的电流主要受到空穴的限制.     

Study on Properties of Intensity Profiles Scattered from the Self-Affine Fractal Random Surfaces: an Approximate Theory and Simulations

We study the properties of the intensity profiles scattered from the self-affine fractal random surfaces. Weuse the mathematical decay function to approximate the duple negative exponent function in the rigorous theory ofscattering, by letting them have the same maximum value and half-width, and the expression for the half-widths of theintensity profiles in the whole range of the perpendicular wave vector component is obtained. The previous results in thetwo extreme cases are included in the results of this paper. In the simulational verification, we propose a method for thegeneration of self-affine fractal random surfaces, using the square-root of Fourier transform of the correlation function ofthe surface height. The simulated results conform well with the theory.     

Effects of laser intenstiy on the emission direction of fast electrons in laser-solid interactions

The dependence of emission direction of fast electrons on the laser intensity has been investigated. The experimental results show that, at nonrelativistic laser intensities, the emission of fast electrons is mainly in the polarization plane. With the increase of the laser intensity, fast electrons emit towards the laser propagation direction from laser polarization direction. At relativistic laser intensities, fast electrons move away from the laser polarization plane, closely to the reflection direction of the incident laser beam.     

环形斑光束在非线性克尔介质中的自聚焦效应

通过数值求解非线性Schrödinger方程,详细讨论了环形斑光束在非线性克尔介质中的传输特性.当入射光超过一定的功率时,光束产生多级自聚焦现象,自聚焦焦点出现在离轴的环上;自聚焦阈值与环形光束的半径有关;传输过程中光斑存在横向分裂现象,并且分裂与聚焦交替进行;当两个半径不同的同轴环状光束同时在非线性介质中传输时产生耦合效应,耦合效应使其自聚焦增强.     

NiFeNb种子层对坡莫合金磁滞回线的影响

以NiFeNb为种子层，制备(Ni₇₉Fe₂₁)_1-xNb_{x(5nm)/(Ni79Fe21) (20nm)/Ta(3nm)系列膜，并对其颗粒大小、 磁滞回线及表面粗糙度等进行测量，探讨种子层中Nb含量x对坡莫合金磁滞回线的影响.结果 表明，以NiFeNb作种子层能更好地改善坡莫合金的微结构. Nb含量为23％时的磁滞回线有最 小的最大磁能积、矫顽力.种子层影响坡莫合金磁滞回线的一个重要原因是脱附激活能等因 素造成种子层具有不同的表面粗糙度，进而使坡莫合金具有不同的微结构和磁性能. 关键词： NiFeNb种子层 坡莫合金 磁滞回线 粗糙度}     

部分相干光照明下光栅的塔尔博特效应

首先利用部分相干光理论详细地分析了在部分相干光照明下光栅的菲涅耳衍射,给出了观察面上衍射光强分布的一般公式,并就光源的发光面积对光栅塔尔博特效应的影响进行了讨论,得到了光栅衍射光强的分布随着照明光源的发光尺寸的增加而逐渐变得平滑这一结论．并且,当光源发光尺寸增加到毫米量级时,光栅的塔尔博特效应将完全消失。在实验上埘不同发光尺寸的扩展作相干光源照明光栅时的菲涅耳衍射光强进行了测量,实验结果与理论分析得出的结论相符合。