Nanosecond laser ablation and deposition of silicon

Nanosecond-pulsed KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) lasers were used to ablate a polycrystalline Si target in a background pressure of <10⁻⁴ Pa. Si films were deposited on Si and GaAs substrates at room temperature. The surface morphology of the films was characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Round droplets from 20 nm to 5 μm were detected on the deposited films. Raman Spectroscopy indicated that the micron-sized droplets were crystalline and the films were amorphous. The dependence of the properties of the films on laser wavelengths and fluence is discussed.     

某光电雷达稳定平台关键部件转板的动态特性分析

 转板是光电雷达稳定平台的关键元件之一。为了更好地设计和分析某光电雷达稳定平台的转板,运用Pro E软件对其进行三维实体建模,合理简化后,进入Ansys软件界面建立有限元模型。应用有限元理论和Ansys软件对其进行动态特性分析,得到了转板前八阶模态的固有频率和振型,以及要求范围内的谐响应。对比了不同方法划分网格的网格质量,采取不同材料得到了不同模态。分析结果表明：设计的转板在关心的频段0~50 Hz,2 000 Hz~8 000 Hz内不发生共振,符合设计要求。     

Growth of cubic MgxZn1−xO alloy films by electron beam evaporation

We report the growth of cubic Mg_xZn_1−xO alloy thin films on quartz by electron beam evaporation. It can be found that all the samples have sharp absorption edges by the absorption measurements. X-ray diffraction measurements indicate the Mg_xZn_1−xO films are cubic phase with preferred orientation along the (1 1 1) direction. Energy dispersive spectrometry (EDS) demonstrates that the Mg concentration in Mg_xZn_1−xO films is much higher than the ceramic target used, and the composition can be tuned in a small scope by varying the substrate temperature and the beam electric current. The reasons of this phenomenon are also discussed.     

表面活性剂增敏光度法测定锌

在弱酸性(pH=4.5)介质中,非离子表面活性剂Tween-80存在下,7-(苯并噻唑-2-偶氮)-8-羟基喹啉-5-磺酸(BTAQS)与锌形成2:1的紫色配合物,最大吸收波长位于580nm处,表观摩尔吸光系数为7.4×104L·mol-1·cm-1,锌含量在0-6μg/25mL范围内符合比耳定律。测定矿样中的锌,结果满意。     

“天光”一号MOPA系统光学元件加工与镀膜的进展

本文阐述了在中国原子能科学研究院“天光一号”ＫｒＦ激光核聚变实验装置上，ＭＯＰＡ系统光学元件加工与镀膜研究工作的进展。实验测量结果表明，加工后的基片表面均方根粗糙度对于Ｋ９光学玻璃与熔融石英玻璃来说分别为σｒｍｓ＝１．８±０．５ｎｍ，σｒｍｓ＝２．０±０．４ｎｍ。镀ＨｆＯ２／ＳｉＯ２高反射膜的光学元件的反射率与破坏阈值分别为Ｒ＞９９．５％，Ｅｔｈ＝１．３０～１．３３Ｊ／ｃｍ２。镀Ａｌ２Ｏ３／ＭｇＦ２增透膜的光学元件的透射率与破坏阈值分别为Ｔ＞９９．５％，Ｅｔｈ＝１．３～１．９７Ｊ／ｃｍ２。     

灯泵浦激光器输出激光稳定性实验研究

分析了灯泵浦激光器的特点以及影响其输出激光稳定性的原因,提出了在激光器谐振腔内加一个“Q开关”的方法来控制输出激光的稳定性,以氙灯泵浦的被动锁模Nd:YAG激光器为例进行了实验研究,证实了此方案是可行的.     

High speed and wide temperature range uncooled 1.3-μm ridge waveguide DFB lasers

A 1.3-μm wavelength vertical-mesa ridge waveguide mulitple-quantum-well （MQW） distributed feedback （DFB） laser with high directly modulated bandwidth and wide operation temperature range is reported. With the optimization of the strained-layer MQWs in the active region, the surrounding graded-index separated-confinement-heterostructure waveguide layers, together with the optimization of the detuning and coupling coefficient of the DFB grating, high directly modulation bandwidth of 16 GHz at room temperature and wide working temperature range from -40 to 85 ℃ are obtained. The mean time to failure （MTTF） is estimated to be over 2×10^6 h. The device is suitable as light source of high-bit-rate optical transmitters with small size and reduced cost.     

Entanglement and quantum phase transition in alternating XY spin chain with next-nearest neighbouring interactions

By using the method of density-matrix renormalization-group to solve the different spin spin correlation functions, the nearest-neighbouring entanglement （NNE） and the next-nearest-neighbouring entanglement （NNNE） of one-dimensional alternating Heisenberg XY spin chain are investigated in the presence of alternating the-nearestneighbouring interaction of exchange couplings, external magnetic fields and the next-nearest neighbouring interaction. For a dimerised ferromagnetic spin chain, the NNNE appears only above a critical dimerized interaction, meanwhile, the dimerized interaction a effects a quantum phase transition point and improves the NNNE to a large extent. We also study the effect of ferromagnetic or antiferromagnetic next-nearest neighbouring （NNN） interaction on the dynamics of NNE and NNNE. The ferromagnetic NNN interaction increases and shrinks the NNE below and above a critical frustrated interaction respectively, while the antiferromagnetic NNN interaction always reduces the NNE. The antiferromagnetic NNN interaction results in a large value of NNNE compared with the case where the NNN interaction is ferromagnetic.     

离焦激光直写的线宽稳定方法

为了提高激光直写加工衍射光学元件时的线条质量,提出一种离焦激光直写的线宽稳定方法.该方法通过同时调节激光功率和离焦量,使光刻胶的曝光阈值处于线宽对曝光量的变化率较小位置,从而可以弱化线宽对实际曝光量或光刻胶阈值等变化的敏感度,提高利用离焦方法进行衍射光学元件制作时的线宽稳定性.推导了稳定线宽后的光功率控制模型和线宽模型,模型中的变量仅为离焦量,降低了光功率控制的复杂性.利用632.8 nm的He-Ne激光和NA-0.1的物镜在CCD上对采用该方法后的离焦线宽模型进行验证,实验结果与理论模型吻合较好.该方法对于线宽稳定度较高的衍射光学元件制作具有重要价值.     

p-HPcZn与肌红蛋白结合性能的研究

利用荧光光谱和同步荧光光谱技术研究了在模拟人体生理条件下β-四(羧基苯氧基)锌酞菁（p-HPcZn）与肌红蛋白的相互作用。p-HPcZn能够显著地猝灭肌红蛋白的荧光,说明两者之间存在着很强的相互作用。变温荧光光谱实验的结果确证该作用可以导致p-HPcZn分子和肌红蛋白分子之间形成复合物,使得p-HPcZn可以通过静态猝灭有效地猝灭了肌红蛋白的荧光。通过对荧光光谱的数据进行处理得知,p-HPcZn分子和肌红蛋白分子形成复合物的结合常数为2.481×105,结合位点n为0.444。另外,p-HPcZn和肌红蛋白之间发生的相互作用还使肌红蛋白分子的构象发生改变。