Diode-pumped Q-switched Nd:GdVO4/KTP green laser formed with a flat–flat resonator

A diode-pumped acousto-optically Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP green laser formed with a flat–flat resonator was demonstrated. 3.05 W of average green output power at pulse repetition frequency (PRF) of 40 kHz was obtained with an optical conversion efficiency of 18.4%, the effective intracavity frequency-doubling efficiency was 57%. At the incident pump power of 15 W, the shortest laser pulse occurred at PRF of 25 kHz with FWHM width of 14 ns, yielding the highest peak power of 7.44 kW; while the largest pulse energy of 0.14 mJ was achieved at PRF of 15 kHz.     

Investigation of strain effect on the hole mobility in GOI tri-gate pFETs including quantum confinement

The strain impact on hole mobility in the GOI tri-gate pFETs is investigated by simulating the strained Ge with quantum confinement from band structure to electro-static distribution as well as the effective mobility. Lattice mismatch strain induced by HfO2 warps and reshapes the valence subbands, and reduces the hole effective masses. The maximum value of hole density is observed near the top comers of the channel. The hole density is decreased by the lattice mismatch strain. The phonon scattering rate is degraded by strain, which results in higher hole mobility.     

基于蒙卡和粒子示踪程序的电子成像模拟分析

借助理论分析和数值模拟,设计了基于高能电子束团的辐射成像系统,并通过Geant4和GPT软件对成像系统的相关参数进行了优化。模拟中分析了影响系统空间分辨率及物质厚度分辨率的因素,结果显示,模拟中设计的成像系统空间分辨率达到m量级,并且具有一定的厚度分辨能力。该设计指标满足对一定厚度及结构的样品进行成像的要求。     

A study on small-world brain functional networks altered by postherpetic neuralgia

Understanding the effect of postherpetic neuralgia (PHN) pain on brain activity is important for clinical strategies. This is the first study, to our knowledge, to relate PHN pain to small-world properties of brain functional networks. Functional magnetic resonance imaging (fMRI) was used to construct functional brain networks of the subjects during the resting state. Sixteen patients with PHN pain and 16 (8 males, 8 females for both groups) age-matched controls were studied. The PHN patients exhibited decreased local efficiency along with non-significant changes of global efficiency in comparison with the healthy controls. Moreover, regional nodal efficiency was found to be significantly affected by PHN pain in the areas related to sense (postcentral gyrus, inferior parietal gyrus and thalamus), memory/affective processes (parahippocampal gyrus) and emotional activities (putamen). Significant correlation (p < 0.05) was also found between the nodal efficiency of putamen and pain intensity in PHN patients. Our results suggest that PHN modulates the local efficiency, and the small-world properties of brain networks may have potentials to objectively evaluate pain information in clinic.     

超高精细度微光学腔共振频率及有效腔长的精密测量

超高精细度微共振器是实现原子或者其他偶极子与腔强耦合作用的基本部分, 在腔量子电动力学(QED)、弱光非线性效应及微光学器件研究中扮演着重要的角色. 微腔基本参数的精密测量最终可以确定腔与原子的耦合系数、腔场衰减率, 对决定系统的动力学特性具有重要的意义. 但是由于超高精细度光学微腔本身的构造和多层镀膜的特点, 高精度地确定其共振频率及有效腔长存在一定困难. 本文结合修正的多层介质膜模型, 实验上完成了膜层为37层的超高精细度光学微腔在不同共振频率下有效腔长的精密测量, 获得了超高精细度光学微腔的共振频率及波长; 理论计算分析与实验测量结果相符, 对纵模间隔的测量精度误差低于0.004 nm, 较为修正前提高了约两个量级. 同时给出了对应不同模式数下, 光波渗入到介质中的深度. 该方法可望应用到其他微共振器的精密测量中. 关键词： 光学微腔 高精细度 共振频率     

X-ray spectra induced by slow highly charged Ar q + ions in collision with Nb surface

The X-ray spectra of Nb surface induced by Ar ^q+ (q = 16,17) ions with the energy range from 10 to 20 keV/q were studied by the optical spectrum technology. The experimental results indicate that the multi-electron excitation occurred as a highly charged Ar¹⁶⁺ ion was neutralized below the metal surface. The K shell electron of Ar¹⁶⁺ was excited and then de-excited cascadly to emit K X-ray. The intensity of the X-ray emitted from K shell of the hollow Ar atom decreased with the increase of projectile kinetic energy. The intensity of the X-ray emitted from L shell of the target atom Nb increased with the increase of projectile kinetic energy. The X-ray yield of Ar¹⁷⁺ is three magnitude orders larger than that of Ar¹⁶⁺. Supported by the National Natural Science Foundation of China (Grant Nos.10774149 and 10405025)