亚微米光栅的制作和零级衍射效率滤波特性的验证

从亚微米光栅的特点出发,分析了应用于防伪技术领域的亚微米光栅的各项关键制作技术和特点,制作了具有零级衍射效率滤波特性和用于光变色防伪的亚微米光栅,光栅零级衍射效率滤波特性的测量结果与使用耦合波理论计算得到的结果是完全一致的。由此可以根据防伪技术所需要的滤波特性设计亚微米光栅的参数。     

亚微米光栅零级衍射特性的数值研究

用耦合波理论分析了亚微米光栅对光波场的衍射作用,给出了在TE和TM偏振入射条件下矩阵形式的耦合波方程,研究了光栅在TE偏振入射条件下可见光波段内的反射和透射零级衍射特性。亚微米光栅零级衍射效率是波长、偏振和入射角的函数,在不同照明、观察和光栅参数条件下,光栅零级衍射具有非常复杂的光谱结构,经过适当的优化光栅参数,零级衍射具有许多独特的衍射特性,在许多应用领域具有广泛的应用前景。     

凹槽深度及吹风比的不确定性对动叶叶顶冷却特性影响研究

耦合非嵌入式多项式混沌展开、稀疏网格技术和RANS方程求解技术,建立凹槽叶顶气热不确定性量化传播模型。在表征加工误差导致凹槽深度变化的不确定性和运行工况波动导致吹风变化的不确定性的基础上,量化凹槽深度、孔吹风比的不确定性对凹槽状叶顶气膜冷却特性的影响。获得叶顶平均气膜有效度相对于均值变化的概率,揭示凹槽叶顶气热性能对凹槽深度和吹风比的敏感性。     

聚合物光栅生物传感器光信号检测滤波电路

矩形光栅1级和0级衍射效率之比对光栅的凹槽深度敏感,介绍了将其应用于聚合物光栅生物传感器的原理和光栅衍射光信号检测电路系统原理。设计了锁相放大器的信号通道滤波器,获得带宽不大于1kHz的窄带滤波特性;利用相敏检测器(PSD)结合二阶巴特沃思低通滤波器,使等效噪声带宽限制在20Hz以内,避免了工频干扰,实验结果表明系统输出信噪比SNR可达4 000以上。     

基于纳米压印的大角度衍射光学元件批量化制备方法

针对大角度(大于50°)衍射光学元件低成本、批量化制备的需求,提出一种基于纳米压印技术的制备方法.首先利用光学曝光技术或电子束直写技术制备衍射元件的原始母板,然后将原始母板的结构通过纳米压印过程复制到压印胶上,完成衍射光学元件的制备.由于纳米压印母板可以多次重复使用,降低了制作成本,提高了效率.用该方法制备了不同特征尺寸(最小为250nm,衍射全角为70°)的衍射光学元件,具有良好的衍射效果,实现了对高深宽比浮雕结构的高保真复制.该技术可实现从微米到纳米跨尺度兼容的衍射光学元件的高保真、低成本、批量化制备.     

微米光栅加速度计的加工与性能研究（英文）

介绍了一种以微米衍射光栅为敏感元件的微机电加速度计敏感头的加工和性能。硅质量块底部加工有铝反射膜,透明玻璃基底上制作有金微米光栅,中间为空气腔,经硅玻璃阳极键合,构成敏感头的核心敏感部件。光源透过透明基底,照射在光栅上,在反射场内会产生一系列衍射级次,且各级次衍射光强与外界加速度之间呈函数关系。完成了微米光栅加速度计敏感头的加工,搭建了实验测试平台,完成了加速度计的灵敏度以及静电驱动性能测试。为未来新型集成式微米光栅加速度计设计和加工提供参考。     

MOCVD方法生长ZnO微米柱的结构与光学性质

通过X射线衍射、扫描电子显微镜和变温光致发光光谱对MOCVD方法生长在蓝宝石衬底上的ZnO微米柱材料的结构及发光特性进行了表征.X射线衍射结果表明,ZnO具有良好的c轴择优取向,扫描电子显微镜图中可观察出ZnO微米在呈六角结构生长,半径约为0.5～1.5μm.样品的发光光谱通过He-Cd激光器的325nm线激发,从光谱中发现低温(81K)下出现极强的与激子相关的带边发光峰,温度升高到360K时与自由激子相关的紫外发射峰仍然是清晰可见.     

微米光栅加速度计的加工与性能研究

介绍了一种以微米衍射光栅为敏感元件的微机电加速度计敏感头的加工和性能。硅质量块底部加工有铝反射膜,透明玻璃基底上制作有金微米光栅,中间为空气腔,经硅玻璃阳极键合,构成敏感头的核心敏感部件。光源透过透明基底,照射在光栅上,在反射场内会产生一系列衍射级次,且各级次衍射光强与外界加速度之间呈函数关系。完成了微米光栅加速度计敏感头的加工,搭建了实验测试平台,完成了加速度计的灵敏度以及静电驱动性能测试。为未来新型集成式微米光栅加速度计设计和加工提供参考。     

沉积时间对球状微米金刚石聚晶结构的生长及其场发射特性影响

利用微波等离子体化学气相沉积法,在覆盖金属钛层的陶瓷衬底上,通过改变沉积时间制备出不同结构的类球状微米金刚石聚晶碳膜.通过扫描电子显微镜、喇曼光谱、X射线衍射谱对碳膜进行了分析测试,并研究了不同沉积时间下沉积的类球状微米金刚石聚晶薄膜的场致电子发射特性,结果显示:不同的沉积时间所制备的碳膜形貌有很大变化,场致电子发射的...     

类球状微米金刚石聚晶的场发射

在覆盖金属钛层的陶瓷上,采用微波等离子体化学气相沉积(MPCVD)法制备出类球状微米金刚石聚晶薄膜。利用扫描电子显微镜、拉曼光谱,X射线衍射,分析了薄膜的结构和表面形貌。测试了类球状微米金刚石聚晶膜的场致电子发射特性。开启电场仅为0.55V/μm,在2.18V/μm的电场下,其场发射电流密度高达11mA/cm2。仔细分析了膜的发射过程,发现类球状微米金刚石聚晶的结构对发射有很大影响,并对其发射机理进行了研究。     

Influence of grooves in the electromagnetic transmission of a periodic metallic grating filter

The light transmittance of metal film with periodic slits and grooves structure has been investigated. It was demonstrated that the grooves significantly affect the transmittance of the metal film. The structure excavating two grooves symmetric to the central slit in a cell of a period grating displays a dent in the transmission spectrum comparing with the structure with only one slit in the cell. Deepening the grooves moves the dents to the longer wavelengths in the transmission spectrum. An analytical equation is also provided to approximately locate the dents. The grooves in the grating filter supply the advantage of removing the needless transmission of certain frequency.     

不同微槽结构绝缘子真空沿面闪络特性

针对单极性脉冲电压下不同微槽结构绝缘子真空沿面闪络特性开展实验研究。根据二次电子运动特性,设计了多种微槽宽度,对比了微槽结构和平面结构的绝缘子耐压特性差异。槽宽为1mm的微槽样品耐压水平与平面结构样品耐压水平相当,槽宽小于1mm的样品组耐压水平均高于平面结构样品,最高电压提高倍数约为1.4,说明一定尺寸范围内的微槽设计将提高绝缘子真空耐压水平。通过电场强度计算分析微槽结构对二次电子运动的影响过程可知,较大的微槽宽度可使电子限制在槽内运动,较小的微槽宽度将抑制初始电子的发展,最终二者都能达到抑制闪络的目的。通过显微镜观测各组样品表面特征,材料表面微观缺陷将可能降低材料耐压水平。     

Effect of groove shape on flow characteristics around a circular cylinder with grooves

In the flow around a circular cylinder, a sudden decrease in the drag force occurs at a high Reynolds number, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the circular cylinder surface. In this paper, in order to make clear the flow characteristics around a circular cylinder in the case of changing the shapes of grooves, the drag coefficient, pressure distribution, velocity distribution and turbulent distribution were measured. Moreover the flow around the cylinder was analyzed by applying the RNGk · ∈ turbulent model, and the surface flow pattern was investigated using the oil-film technique. From these results, it is clear that the drag coefficient of a circular cylinder with triangular grooves decreases by about 15% compared with that of a circular cylinder with arc grooves.     

Multi-interaction of surface wave between subwavelength grooves surrounding a single metallic slit

We propose a physical understanding of scattering by subwavelength grooves surrounding a single perfect conductor slit based on the superposition of a cylindrical traveling surface wave and a standing surface wave. The collective reflection coefficient was introduced to handle the multi-interaction of the surface wave between subwavelength grooves, and a slit–grooves focusing structure was designed to demonstrate its validity. In comparison to numerical simulations by the finite difference time domain method, the proposed method proves effective in describing the multi-interaction behavior of a surface wave and in further refining the phase perturbation at the grooves’ exits.     

Effect of the number of grooves on flow characteristics around a circular cylinder with triangular grooves

In the flow around a circular cylinder, a sudden decrease in the mean drag coefficient occurs at a high Reynolds number, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the cylinder surface. In this paper, in order to make clear the flow characteristics around a cylinder with 20, 26 and 32 triangular grooves, the mean drag coefficient, pressure distribution, velocity distribution and turbulence intensity distribution were measured. Moreover, the flow around the cylinder was analyzed by applying the RNGk − ɛ turbulent model, and the surface flow pattern was investigated using the oil-film technique. From these results, it was found that a sudden decrease in the mean drag coefficient of a cylinder with 32 triangular grooves occurs at a lower Reynolds number compared with 20 and 26 triangular grooves.     

应用碳化硅表面改性技术降低全息-离子束刻蚀光栅刻槽的粗糙度

采用具有良好比刚度和热稳定性的碳化硅材料作为基底,使用全息-离子束刻蚀技术制作了光栅。碳化硅材料表面固有缺陷导致制作的光栅刻槽表面粗糙度高,槽底和槽顶粗糙度分别达到了29.6 nm和65.3 nm (R_q)。通过等离子辅助沉积技术在碳化硅表面镀制一层均匀的硅改性层,经过抛光可以获得无缺陷的超光滑表面。XRD测试表明制备的硅改性层为无定形结构。原子力显微镜的测试结果表明:经过抛光后,表面粗糙度为0.64 nm(R_q)。在此表面上制作的光栅刻槽表面粗糙度明显降低,槽底和槽顶粗糙度分别为2.96 nm和7.21 nm,相当于改性前的1/10和1/9。     

刻槽结构高功率微波输出窗次级电子倍增效应

从理论上分析了周期性矩形刻槽对喇叭天线输出窗真空侧次级电子倍增的影响。采用动力学方法分析得到电子沿介质窗表面运动的渡越时间和碰撞能量,验证得到一定尺寸的矩形刻槽介质窗可以有效抑制次级电子倍增效应。在此情况下,对比了刻槽和不刻槽两种输出窗的辐射特性,发现周期2 mm、宽度1 mm、深度1 mm的矩形刻槽对介质窗辐射特性的影响可以忽略。     

Mechano-chemical AFM nanolithography of metallic thin films: A statistical analysis

A mechano-chemical atomic force microscope (AFM) nanolithography on a metallic thin film (50 nm in thickness) covered by a spin-coated soft polymeric mask layer (50–60 nm in thickness) has been introduced. The surface stochastic properties of initial grooves mechanically patterned on the mask layer (grooves before chemical wet-etching) and the lithographed patterns on the metallic thin film (the grooves after chemical wet-etching) have been investigated and compared by using the structure factor, power spectral density, and AFM tip deconvolution analyses. The effective shape of cross section of the before and after etching grooves have been determined by using the tip deconvolution surface analysis. The wet-etching process improved the shape of the grooves and also smoothed the surface within them. We have indicated that relaxation of the surface tension of the deposited mask layer after the AFM scribing is independent from surface density of the grooves and also their length scale. Based on the statistical analysis, it was found that increase of the width of the grooves after the wet-etching and also relaxation of surface tension of the mask layer resulted in a down limit in the size of the metallic nanowires made by the combined nanolithography method. An extrapolation of the analyzed statistical data has indicated that, in this method, the minimum obtainable width and length of the metallic nanowires are about 55 nm and 2 μm, respectively.     

具有微型沟槽结构旋转圆盘减阻的实验研究

建立了开式旋转圆盘系统减阻实验平台,对圆盘螺线沟槽减阻进行实验研究,并可以结合数值研究手段对微型沟槽减阻的机理进行研究。实验结果表明圆盘开槽面积为7.4%时,螺线微型沟槽使得旋转圆盘的最大减阻率达6.1%,V型沟槽两侧的压力差所产生的正扭矩是其减阻的主要原因。沟槽还能起到提高圆盘内径与外径处的静压差的效果。研究结果还表明,采用和平板减阻相同的无量纲尺寸的沟槽会引起圆盘表面的剪应力较大增加。     

侧面泵浦高功率双包层光纤激光器的表面弧形金属槽结构的制作和分析

侧面耦合高功率泵浦光技术是获得高功率稀土光纤激光器的关键技术之一。介绍了一种用于侧面泵浦高功率双包层光纤激光器的表面弧形金属槽结构的制作工艺,并且针对已经实验制作出来的表面连续弧形金属凹槽的侧面耦合结构进行了严格的矢量电磁场理论计算,将120°弧形凹槽等效近似为多层等高不等宽的矩形槽并运用透射矩阵算法对这种近似后的多层矩形结构进行优化设计。这种结构可以用于大功率激光二极管阵列的侧面泵浦中,尤其可用于条形半导体激光器侧面泵浦双包层掺杂光纤,以制作各种大功率稀土光纤激光器。