差动电磁作动器的超大型光学仪器 隔振基础的主动控制机理

提出了一种基于差动电磁作动器的超大型光学仪器隔振基础的主动控制机理。该控制机理采用差动布置方案,使电磁作动器变为输出力和控制电流呈线性关系的线性作动器,再利用小阻尼条件下,绝对速度反馈与Skyhook控制方法性能接近且易于工程实现的特点,采用了绝对速度反馈的控制方法,可在不改变中/高频隔振性能的前提下大幅提高谐振区隔振性能。实验结果表明:利用所提出的控制机理,在时域上,z、θ_x和θ_y三个自由度的速度(角速度)均方根值分别由10.06 μm/s、4.16×10^－6rad/s和4.65×10^－6rad/s降至3.38 μm/s、1.76×10^－6rad/s和1.49×10^－6rad/s;在频域上,三个自由度谐振区隔振性能均有约10 dB的提高。     

光折变晶体两波耦合增益系数强度特性理论研究

对两中心模型光折变晶体两波耦合增益系数Γ,总的有效陷阱密度N_eff和强度特性因子η(I)的强度特性进行了理论研究。结果显示在两中心模型的光折变晶体中,Γ,N_eff和η(I)有着复杂的特性。当S_Dγ_T/S_Tγ_D小时,对于A类和B类两中心晶体,N_eff随强度的增加而增加最终趋于饱和,当S_Dγ_T/S_Tγ_D大时,对于A类晶体N_eff增加到一个最大值后稍有减少,而对于B类晶体,N_eff增加到最大值后然而有较大的减少。不同类型晶体增益系数Γ有着不同的强度特性是由于晶体中有着不同的能级结构。     

高平均功率腔内和频蓝光Nd:YAG激光器

高平均功率蓝光激光是当前固体激光技术研究热点之一。尽管通过Nd³⁺的⁴F_3/2→⁴I_9/2态谱线倍频可获得瓦级蓝光输出,然而其准三能级物理特性严重限制其更高功率输出。研究了Nd³⁺离子⁴F_3/2→⁴I_13/2态1.3 μm谱线腔内三倍频产生高平均功率蓝光激光,获得4.3 W蓝光激光输出,重复频率3.5 kHz,脉冲宽度150±10 ns,光束质量M²因子约为5±1。研究表明:Nd∶YAG晶体1.3 μm多谱线振荡是制约实验结果的重要因素,若克服多谱线振荡问题,有望获得10 W级蓝光激光输出。     

ZnO薄膜非线性光学特性的实验研究

利用金属有机化学气相沉积(MOCVD)技术在蓝宝石衬底上生长一层高质量的ZnO薄膜。为了考察沉积温度对样品的非线性特性的影响,在200~500 ℃生长了一系列ZnO薄膜。用X射线衍射谱(XRD)及扫描电镜(SEM)对样品结构进行了评价。以Nd:YAG激光器输出的1.06 μm的激光为基频光,对ZnO薄膜样品的二阶及三阶非线性光学特性进行了实验研究。实验发现,对于250 ℃沉积温度的样品有较强的非线性效应,实验测得的二阶非线性极化张量 χ ⁽²⁾_ZZZ=9.2 pm/V, 三阶有效非线性系数χ⁽³⁾=5.28×10^－20 m²/V²。     

68.5 W连续输出1 060 nm波段半导体激光列阵模块

利用InGaAs/InGaAsP应变量子阱外延层材料制作出高功率半导体激光列阵模块。激光芯片宽1 cm,腔长1200 μm,条宽200 μm,填充密度为50%,前后腔面光学膜分别为单层Al₂O₃和Al₂O₃/5(HfO₂/SiO₂)/HfO₂,室温连续输出功率达到68.5 W,器件光谱中心波长为1 059 nm,光谱宽度(FWHM)为9 nm。     

全固态589 nm复合腔连续波和频激光器

给出了一种复合腔结构和频激光器,用2台激光二极管阵列(LDA)经过光纤耦合分别单独端面抽运Nd:YVO₄和Nd:YAG晶体,其中Nd:YVO₄和Nd:YAG晶体所选择的能级跃迁分别为⁴F_3/2-⁴I_11/2和⁴F_3/2-⁴I_13/2,其对应激光跃迁波长分别为1 064 nm和1 319 nm,两基频激光束分别在两个子谐振腔中振荡,在其交叠区利用KTP II类临界相位匹配(CPM)进行腔内和频,获得了589 nm的和频激光。当抽运功率为8 W/14 W时获得了340 mW连续波TEM₀₀黄激光输出。光束质量因子M²<1.2,激光输出功率噪声低,4 h功率不稳定度小于±3％。该复合腔结构是实现LDA泵浦589 nm全固态黄光激光器一种有效的和频方法。     

CW可调谐单频环形染料激光器β-BaB2O4晶体内腔倍频

本文论述了利用β-BaB₂O₄晶体进行内腔连续波环形染料激光器倍频,获得了可调谐单频紫外相干辐射。在292nm附近,用3WAr⁺激光(全谱线)泵浦,得到非线性转换系数～8.33×10^-4W^-1。通过改变相位匹配角,在288～302nm范围内输出连续可调谐紫外谐波。β-BaB₂O₄晶体角灵敏度～27cm^-1/mrad。     

模拟高能空间环境对光学材料在1050埃到3000埃之间紫外透过率的影响

在辐照前和第一次在1.0兆电子伏而第二次在2.0兆电子伏用10¹⁴电子/厘米²辐照之后从1050埃到3000埃范围测量了 LiF、MgF₂、CaF₂、BaF₂、Al₂O₃、和熔石英的透过率.当采用 Al₂O₃使熔石英,二氢化铵磷酸盐(ADP),方解石和 Corning 玻璃滤光片9—54和7—54屏蔽开直射电子束的时候,在2.0兆电子伏用10¹⁴电子/厘米²作了类似的测量.     

稀土光学玻璃着色的研究

本文系统地测定了第一过渡金属(Fe,Co,Ni,Cu,Cr,Mn 等)离子和稀土(Ce,Pr,Nd,Sm 等)着色离子在 B₂O₃-BaO,B₂O₃-La₂O₃-BaO,B₂O₃-BaO-SiO₂,B₂O₃-BaO-SiO₂-La₂O₃及氟磷等系统玻璃中的吸收光谱。比较了各种着色离子对不同系统玻璃的着色情况。阐述了3d 轨道部分填充的过渡金属离子及具有4f 壳层受5s,5p 电子层屏蔽的 Ce,Pr,Nd,Sm 离子在玻璃中的着色机理。并讨论了玻璃生成体B^a+,si⁴⁺,P⁵⁺阳离子及网络外体离子 La³⁺,F^-对玻璃着色的影响。最后提出了稀土玻璃中稀土杂质含量的允许值。     

OsO4窄谐振的CO2激光器频率的稳定

本文说明了OsO₄窄谐振的CO₂激光器频率稳定的可能性。实验室的实验装置在平均值时间取100秒时,获得了2×10^-11的频率稳定性。现已证明,OsO₄分子由于其固有的特性,当做为基准而用它来稳定CO₂激光器的频率时,前途是很有希望的。     

Atomic-force-microscope-compatible near-field scanning microwave microscope with separated excitation and sensing probes

We present the design and experimental results of a near-field scanning microwave microscope working at a frequency of 1 GHz. Our microscope is unique in that the sensing probe is separated from the excitation electrode to significantly suppress the common-mode signal. Coplanar waveguides were patterned onto a silicon nitride cantilever interchangeable with atomic force microscope tips, which are robust for high speed scanning. In the contact mode that we are currently using, the numerical analysis shows that contrast comes from both the variation in local dielectric properties and the sample topography. Our microscope demonstrates the ability to achieve high resolution microwave images on buried structures, as well as nanoparticles, nanowires, and biological samples.     

基于同轴光子带隙晶体的应变传感器

基于微波网络理论,提出了一种基于变绝缘层的同轴光子带隙晶体应变传感器的设计方法。给出了同轴光子带隙晶体传感器的结构形式,推导了传感器带隙极值频率与晶体电长度之间的关系。根据给定监测频点设计了传感器的几何尺寸及材料参数,计算了传感器的S参数,计算结果与仿真结果相吻合。分析了提高该传感器灵敏度和品质因数的方法,并搭建了实验测试平台。实验结果表明:当应变量由0με提高至10 000με时,极值频率由2.450GHz移至2.432GHz,频移量为18 MHz,灵敏度为1.8kHz/με。得到的实验结果与仿真结果相吻合,验证了本文所提出的基于变绝缘层的同轴光子带隙晶体应变传感器设计方法的可行性和有效性。该传感器可满足不同灵敏度需求下对应变的实时监测。     

全球卫星导航系统接收机的正交二分频器设计

将全球卫星导航系统(GNSS)接收机用于手持移动设备必须降低正交二分频器等大功耗模块的功耗,因此,本文提出了工作于1V电压以下的正交二分频器.使用提出的正交二分频器可使电路在各工艺角下高速稳定的工作,并大大降低模块的功耗.首先,介绍已有的高速二分频器.接着,计算了所提出结构的直流静态偏置,并对提岀的锁存器进行小信号建模和分析.最后,根据小信号模型分析得到的条件和GNSS接收机的应用要求,设计了提出的低功耗结构.实验结果表明:提出的二分频器最高工作频率为6.55 GHz,最低可工作到0.25 GHz,消耗电流为0.8mA,占用面积为0.014 4 mm2.提出的电路结构在0.13 μm CMOS工艺上实现,可稳定工作于1V电压下,目前已成功应用于低功耗的移动GNSS接收机中.     

Hollow target magnetron-sputter-type solid material ion source

A thin-walled aluminum (Al) hollow electrode has been inserted into an ion source to serve as an electrode for a radio frequency magnetron discharge. The produced plasma stabilized by argon (Ar) gas sputters the Al electrode to form a beam of Al(+) and Ar(+) ions. The total beam current extracted through a 3 mm diameter extraction hole has been 50 μA, with the Al(+) ion beam occupying 30% of the total beam current.     

晶体已加工表面频率特征对亚表层温度场的影响

为了更加准确地分析表面形貌对KH2PO4(KDP)晶体元件激光损伤和使用性能的影响，通过功率谱密度和连续小波变换对KDP晶体已加工表面存在的实际频率特征进行提取和重构。利用波动光学理论分析经入射波长1.064 μm、功率20 MW/μm2的激光束照射1 ns后，表面频率特征对KDP晶体亚表层光场及温度场的影响。结果表明，当表面频率特征的波长越接近入射光波长1.064 μm，KDP晶体亚表层的光场畸变现象越严重，会造成局部聚焦，温度越高；当波长超过20 μm时，在振幅不变的情况下，最高温度随着波长的增加基本不变。通过切削实验获得的KDP晶体已加工表面上明显存在的波长分别为14 μm、50 μm和140 μm，对KDP晶体亚表层造成的温升分别为56 K、22 K和12 K。当波长相同时，KDP晶体的最高温度与表面频率幅值成线性关系。随着表面频率波长的增加，温度最高点的位置向KDP晶体内部延伸。     

Development of electrically controlled polishing with dispersion type ER fluid under AC electric field

This paper shows that a dispersion type functional fluid and AC electric field may be used to control the distribution of abrasives in free-abrasive polishing and to improve surface roughness and finishing time. In the case of polishing conductive materials, such as cemented carbide, an AC electric field created by a mono-pole electrode has concentrated abrasives in the polishing area. To obtain a minimum surface roughness, a peak-to-valley voltage of 2 kV at a frequency of 0.8 Hz has been applied. Then the surface roughness of a cemented carbide plate was reduced from 0.65 μm Ra to 0.02 μm Ra in 5 min. But to polish non-conductive materials, such as glass and semiconductors, a multi-layered concentric electrode must be introduced. The surface roughness of borosilicate glass plates has been reduced from 13.5 nm Ra to 7.5 nm Ra in 3 min under the optimum AC electric field gradient of 2 kV/mm and 0.8 Hz frequency.     

MEMS硅半球陀螺球面电极成形工艺

由于球面电极是曲面结构,电极各处的电感耦合等离子体(ICP)刻蚀深度不一致,在加工过程中常发生球面电极还未刻蚀到位而谐振器已被破坏的现象,故本文提出了新的球面电极成形工艺。基于ICP刻蚀固有的lag效应,采用刻蚀窗口宽度由60μm渐变至10μm的V形刻蚀掩模调制电极各处的刻蚀速度,在电极各处获得了基本一致的归一化刻蚀速度(2.3μm/min)。利用台阶结构拟合球面电极的3D曲面结构,并保证通刻阶段的硅厚度基本一致为150μm来消除球面电极加工时最薄处已经刻穿阻挡层并破坏谐振器而最厚处还没有刻蚀到位的现象。结合台阶状的二氧化硅掩模对球面电极各点处的硅ICP刻蚀当量进行了调整,使其基本相等,通过一次ICP刻蚀即完成了对硅球面电极的加工。利用提出的方法成功制备出了具有功能性输出的微机电系统(MEMS)半球陀螺的硅球面电极,其最大半径可达500μm。     

一种紧凑型压电叠层直线电机驱动足的优化设计

在使用压电叠层时一般会设计防剪切机构，未设计防剪切机构时需要对驱动足结构进行仿真设计，减小压电叠层所受剪切力。为此，提出在无防剪切机构时电机驱动足的结构优化方法，并对一种紧凑型压电叠层直线压电电机驱动足进行仿真优化。通过优化把横向压电叠层输出端的旋转变形由1.333μm减小至0.061μm，纵向平移变形由1.911μm减小至0.749μm，机构的最大等效应力由253.35MPa减小至189.68MPa，显著改善了压电叠层的工作环境。提出一种并联S形弹簧机构，给出该结构的优化设计方法并进行仿真设计。仿真结果表明:该机构有较大的刚度范围，可以有效降低压电叠层所受剪切力；在相同刚度的情况下，具有弹簧宽度越大最大等效应力越小的特点。     

Ultrasonic response of a piezoelectric aluminum nitride film deposited on silicon

An aluminum nitride (AlN) thick film for ultrasonic transduction was deposited on a silicon wafer by magnetron sputtering. A columnar structure with uniform elemental depth profiles with 40 at.% to 60 at.% (Al-N) concentrations and with a c-axis preferential orientation was observed by X-ray diffraction. The ultrasonic response of the Al/AlN/Si overmoded resonator was characterized from 1.24 MHz to 2 GHz using a vector network analyzer. The time domain transform and the gate features of the vector network analyzer were used to characterize the AlN thick film capabilities in the time and frequency domains. The results show that the obtained resonator operates over a broad frequency range with a central frequency at approximately 930 MHz and a 738 MHz bandwidth at -6 dB. The results were compared with those obtained from a one-dimensional simulation to highlight and predict the AlN response features. A comparison was performed to validate the experimental measurements and to validate the circuit modeling. Overall agreement between the experiment values and the simulation was observed.     

Study on the c-axis preferred orientation of ZnO film on various metal electrodes

ZnO thin film was deposited on various metal electrodes by reactive sputtering, and c-axis preferred orientation of the film has been studied. ZnO, which has high piezoelectricity, is promising for oscillators or filter devices such as surface acoustic wave (SAW) device, gas sensor, and film bulk acoustic resonator (FBAR). But, for the application of ZnO film for these devices, the film should be grown with c-axis normal to the electrode. In this study, Pt, Al, and Au were deposited on Si wafer, and the surface roughness and crystal structure of the ZnO film on the electrode were investigated using AFM, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Columnar structures of ZnO films were grown with c-axis normal to all electrodes, and among them Pt electrode showed the highest preferred orientation of ZnO film.