Modeling and CW operation of a quasi-three-level 946 nm Nd: YAG laser

A model is developed for an end-pumped quasi-three-level laser with population in the lower laser level at equilibrium such as for transitions to the manifolds⁴I9/2in Nd³⁺,⁴I15/2in Er³⁺,⁵I8in Ho³⁺and³H6in Tm³⁺. It is shown that the effect of residual lower laser level population on laser operation can be treated as a saturable loss. Room temperature operation on the⁴F3/2-⁴I9/2transition in Nd:YAG under CW dye laser pumping has been demonstrated with a threshold as low as 11.5 mW incident power and a slope efficiency of 7 percent with 0.3 percent output coupling. Performance is limited by the low output coupling and diffraction loss.     

Effect of misalignment on electrical characteristics of ACF joints for flip chip on flex applications

The effect of misalignment on the electrical properties of anisotropic conductive film (ACF) joints is investigated in this work. It is found that along with the increase of misalignment, the connection resistance of ACF joints increases. When the misalignment in x-direction is less than 5 μm, the increase rate of connection resistance is quite large. Then, along with the severity of misalignment, the increase rate becomes smaller. Finally, when the misalignment is close to 20 μm, the increase rate rises again. The Holm's electric contact theory is used for understanding the connection resistance variation. On the other hand, with the increase of misalignment in x-direction, the insulation resistance between ACF joints decreases. If the misalignment exceeded 10 μm, the decrease is prominent for the Ni particle ACF joints. This phenomenon can be explained by the effect of dielectric damage of the epoxy.Computer programs are also developed to calculate the variation of the probability of open and shorting after misalignment and predicate the maximum misalignment tolerance. The results show that the open and shorting probability increase abruptly after misalignment. On the view of pad parameters, the open probability is mainly related to the pad area, while the pads gap is critical to the shorting probability. Large pads gap (small pad width) can reduce the shorting probability obviously. On the other hand, enlarging the pad area by increasing pad length decreases the open probability significantly. So comparing to square shape pad, rectangle shape pad can reduce the failure probability greatly.     

XY(H,Li,Na)分子基态的结构与势能函数

运用群论及原子分子反应静力学方法,推导了XY(H,Li,Na)分子基态的电子态及相应的离解极限.并采用密度泛函方法(B3LYP)和二次组态相互作用方法(QCISD)优化计算了XY(H,Li,Na)分子基态的平衡结构、振动频率和离解能.使用QCISD/6-311++G(3df,3pd)方法,对XY(H,Li,Na)分子基态进行了单点能扫描计算,采用最小二乘法拟合Murrell-Sorbie函数得到了相应的势能函数和与该基态相对应的光谱常数(Be,αe,ωe和ωexe),计算结果与实验数据符合得相当好.     

不完全信息群体决策专家权重的集结

本文对于属性权重信息和属性效用信息都不完全的群体多属性决策问题，通过构造属性值区间和运用系统聚类分析法，对群体决策中的专家进行分类，并确定每位专家的权重．     

Newton-Leibniz integration for ket-bra operators in quantum mechanics and derivation of entangled state representations

Newton-Leibniz integration rule only applies to commuting functions of continuum variables, while operators made of Dirac’s symbols (ket versus bra, e.g., |q〉〈q| of continuous parameter q) in quantum mechanics are usually not commutative. Therefore, integrations over the operators of type |〉〈| cannot be directly performed by Newton-Leibniz rule. We invented an innovative technique of integration within an ordered product (IWOP) of operators that made the integration of non-commutative operators possible. The IWOP technique thus bridges this mathematical gap between classical mechanics and quantum mechanics, and further reveals the beauty and elegance of Dirac’s symbolic method and transformation theory. Various applications of the IWOP technique, including constructing the entangled state representations and their applications, are presented.     

A dual-mode multiuser detector for DS-CDMA systems

We introduce a dual-mode multiuser detector that dynamically switches its detection mode between matched-filter and decorrelator operations based on the channel characteristics. This detector significantly reduces the overall computational requirement while maintaining similar performance as that of the decorrelator. The switching mechanism of our dual-mode detector is designed by exploiting the performance-complexity tradeoff between the decorrelator and the matched-filter. Extensions of this idea to other types of multiuser detectors are also proposed     

基于电子现金的新型支付协议

本文提出了一种基于电子现金的新型支付协议,该协议通过第三方实时核算客户拥有的电子现金,但不进行实时转账。协议模型较好地克服了现有在线支付的交易瓶颈问题以及离线支付中电子现金容易被重用、伪造或篡改的问题,在交易过程中有效地保证了安全性,并且实现了电子现金的原子性、匿名性、可分割性和可验证性。     

Co-P非晶态合金电子性质和局域结构的理论研究

根据Co P非晶态合金结构的短程有序和结构中可能存在P -P相互作用的实验事实 ,选择了单磷原子簇模型ConP(n =1～ 5 )和双磷原子簇模型ConP2 (n =1～ 4 ) ,用密度泛函理论方法对其进行计算 .结果表明 ,在单磷Co2 P( 2 ) 、Co3 P( 1) 及Co4P( 2 ) 模型体系中 ,Co原子供给P原子电子 ,与电负性规则一致 ,同时Co和P之间具较强化学作用 ,可以形成稳定的原子簇 ;而在双磷和单磷原子簇Co5P( 1) 模型体系中 ,形成的原子簇不稳定 ,采用单磷Co2 P( 2 ) 、Co3 P( 1) 及Co4P( 2 ) 模型能较好地反映Co P非晶态合金的结构特点 .     

Laser-induced damage of Ta2O5/SiO2 narrow-band interference filters under different 1064 nm Nd:YAG laser modes

The laser-induced damage (LID) behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running mode. The absorption measurement of such coatings was performed with surface thermal lensing (STL) technique. The damage morphologies under the two different laser modes were also studied in detail. It was found that all the filters exhibited a pass-band-center-dependent absorption and laser-induced damage threshold (LIDT) behavior, but the damage morphologies were diverse. The explanation was given with the analysis of the electric field distribution and the operational behavior of the irradiation laser.     

Ultraviolet Luminescence in Mg0.12Zn0.88O Alloy Films

We investigate the origin of ultraviolet （UV） emission from Mg0.12 Zn0.88 O alloy thin films with a wurtzite structure fabricated on c-plane Al2O3 substrates by plasma assisted molecular beam epitaxy. At room temperature, the absorption edge and UV emission band of the Mg0.12Zn0.88O film shift to high-energy side compared with ZnO films. Temperature dependence of the photoluminescence spectra shows that the UV emission is composed of free exciton and neutral donor bound exciton emissions. Two-step dissociation processes of the UV emission are observed with the increasing temperature. The thermal quenching mechanism is attributed to the dissociation of the free exciton from the neutral donor bound exciton in the low temperature region and the dissociation of free electron and hole from the free exciton in the high temperature region.