有机分子激发态非线性吸收的瞬态特性研究

提出了一种通过测量单脉冲光的输入与输出波形来研究激发态非线性吸收的新方法，用这种方法研究了纳秒脉作用下类卟啉镉溶液与甲基橙溶液的三重激发态的非线性吸收特性，前者为反饱和吸收现象，后者是由饱和吸收转化为反饱和吸收的新现象，实验结果验证了理论模拟和正确性。     

长焦距光学系统杂光系数测试仪

报告了一种新的长焦距光学系统杂光系数测量装置,该装置除具有避免了制作大直径积分球的优点外,还能精确测量轴外杂光系数,分析各部分杂光源对杂光系数的影响.     

Measurements of cirrus clouds with a three-wavelength lidar

A three-wavelength lidar system is set up. The backscatter signals of 355, 532, and 1 064 nm are mea- sured simultaneously to derive the optical depth, lidar ratio, and backscatter color ratio of cirrus clouds, respectively. The lidar configuration and the data processing are described. The case study shows that the optical depths of cirrus clouds are not dependent on wavelength while the backscatter color ratios are.     

Stable dual-wavelength erbium-doped fiber ring laser with switchable spacing employing controllable channel loss

A stable dual-wavelength erbium-doped fiber ring laser with switchable spacing is proposed and experimentally demonstrated. An arrayed waveguide grating (AWG) incorporating two fiber optic switches (OS) is used to as the wavelength selector. The ring cavity is divided into two cavities by a 30:70 optical coupler. Equalized dual-wavelength outputs are achieved by controlling the variable optical attenuator (VOA) inserted in the lower loss cavity. The wavelength spacing can be tuned from 0.80 to 12.05 nm. The fiber laser has good optical quality with maximum power fluctuation of 1.5 dB and side mode suppression ratios (SMSRs) higher than 71 dB.     

硅量子点发光的激活及其物理模型研究

在真空或惰性气体中制备的硅量子点发光很弱,硅量子点表面被氢较好钝化后的发光也不强.硅量子点表面的硅氧键或硅氮键能破坏这种钝化并在带隙中形成局域电子态,在局域电子态对应的激活中心有很强的发光.可以用这种方式构建发光物质,控制硅量子点表面的键合可获得不同波长的发光.在硅量子点的发光激活处理过程中,退火是很重要的环节.对于硅量子点发光激活的机理,本文给出了相应的物理模型.实验证明,在600和700 nm波长附近观察到了激活硅量子点的受激发光,在1500 nm到1600 nm波长范围观察到了激活硅量子点的较强发光.     

A M?ssbauer spectroscopic study on the action of Ce in the catalyst for dehydrogenation of etylbenzene to styrene

Two series of Fe-K catalysts for dehydrogenation of ethylbenzene to styrene were prepared with different amounts and different compounds of the additional element Ce. M?ssbauer spectroscopy has been used to determine the Fe compound in the catalyst and to investigate the effect of Ce. The catalytic properties of the catalysts have also been measured. The results show that the element Ce in the catalyst is favorable to form the predecessor of the catalytic active phase, the compound KFe₁₁O₁₇ and that the optimal percentage of CeO₂ is 8%～15% in the catalyst which is favorable to the formation of KFe₁₁O₁₇ and to get better catalytic properties.     

高场强下金属化膜电容器绝缘电阻特性

分析了高电场强度下金属化膜电容器绝缘电阻的特点,得出高电场强度下金属化膜电容器绝缘电阻是电容器介质膜泄漏和自愈过程的综合反映。针对高场强下的应用条件提出一种金属化膜电容器绝缘电阻的测试方法,并对高场强下电容器的绝缘电阻进行测试。测试结果表明:在300~400 V/m工作场强范围内金属化膜电容器绝缘电阻随工作场强增大会急剧减小,由于自愈的作用,绝缘电阻下降幅度随场强增加会逐渐变缓;在20~50 ℃工作温度范围内,金属化膜电容器绝缘电阻随温度升高会急剧减小,同样由于自愈的作用,绝缘电阻下降幅度随温度增高会逐渐变缓。分析得出,高温高场强下金属化膜电容器介质膜泄漏将会导致电容器电压出现明显下降,影响电容器和脉冲功率系统的储能效率。     

Influence of a two-dimensional electron gas on current—voltage characteristics of Al0.3{Ga}0.7 N/GaN high electron mobility transistors

The J-V characteristics of AltGa1 tN/GaN high electron mobility transistors（HEMTs） are investigated and simulated using the self-consistent solution of the Schro dinger and Poisson equations for a two-dimensional electron gas（2DEG） in a triangular potential well with the Al mole fraction t = 0.3 as an example.Using a simple analytical model,the electronic drift velocity in a 2DEG channel is obtained.It is found that the current density through the 2DEG channel is on the order of 10^13 A/m^2 within a very narrow region（about 5 nm）.For a current density of 7 × 10^13 A/m62 passing through the 2DEG channel with a 2DEG density of above 1.2 × 10^17 m^-2 under a drain voltage Vds = 1.5 V at room temperature,the barrier thickness Lb should be more than 10 nm and the gate bias must be higher than 2 V.     

电磁感应双光子带隙的产生和控制

基于电磁感应透明技术, 通过求解原子的密度矩阵方程和电磁场的传输矩阵方程, 研究了被行波场和驻波场共同耦合的一个四能级冷原子介质的稳态光学特性, 发现在特定参数下能够产生一个几乎完美的双光子带隙结构, 在这两个光子带隙对应的频率区域内反射率都均匀地超过95%. 通过改变耦合场的强度和频率, 可以方便地调节这两个光子带隙的位置和宽度. 这一双光子带隙结构可用来实现全光路由和全光开关, 有望在全光信息网络中获得应用.     

Tb2Fe15.5Cr1.5化合物的本征磁致伸缩

通过x射线衍射及磁测量手段研究了Tb2 Fe1 5 5Cr1 5化合物的热膨胀性质及本征磁致伸缩性质 .研究结果表明Tb2 Fe1 5 5Cr1 5化合物在 2 93— 6 72K的温度范围内具有六角相的Th2 Ni1 7型结构 .在 4 32— 5 2 2K的温度范围内具有负热膨胀性质 ,其平均热膨胀系数 α =- 1 5 7× 10 - 5 K .对本征磁致伸缩的研究结果表明Tb2 Fe1 5 5Cr1 5化合物中存在着较强的各向异性的本征磁致伸缩 ,2 93K时其本征体磁致伸缩约为 8. 4× 10 - 3,晶格畸变主要发生在c轴方向上 .磁测量研究结果表明Tb2 Fe1 5 5Cr1 5化合物的居里温度约为 4 94K ,比其母合金Tb2 Fe1 7高约 80K .