劳埃德式紫外激光干涉光刻实验

搭建了劳埃德式紫外激光干涉光刻系统,利用劳埃德镜产生双光束分波阵面干涉,通过精确调整、控制光束的入射角,设计了曝光图样.基础实验部分可以完成一维光栅制备,分析光栅周期与波长、入射角的关系;在拓展实验中,制备设计部分可以完成二维点阵或准晶结构制备,前沿拓展部分可以制备表面等离极化激元微腔.基于劳埃德式激光干涉光刻实验操作便捷、展示度高,同时涵盖光干涉原理的介绍和光路调整、样品制备和表征等实验内容,有助于学生掌握激光干涉光刻的实验技能.     

一种简单高效的制备硅纳米孔阵结构的方法

本文介绍了一种简单高效的制备硅纳米孔阵结构的方法. 利用激光干涉光刻技术, 结合干法和湿法刻蚀工艺, 直接将光刻胶点阵刻蚀为硅纳米孔阵结构, 省去了图形反转工艺中的金属蒸镀和光刻胶剥离等必要步骤, 在2英寸的硅 (001) 衬底上制备了高度有序的二维纳米孔阵结构. 利用干法刻蚀产生的氟碳有机聚合物作为湿法刻蚀的掩膜, 以及在干法刻蚀时对样品进行轻微的过刻蚀, 使SiO₂点阵图形下形成一层很薄的硅台面, 是本方法的两个关键工艺步骤. 扫描电子显微镜图片结果表明制备的孔阵图形大小均匀, 尺寸可控, 孔阵周期为450 nm, 方孔大小为200–280 nm. 关键词： 激光干涉光刻 纳米阵列 刻蚀 氟碳有机聚合物     

入射光束角度及强度偏差对多光束干涉光刻结果的影响

建立了多光束干涉光刻干涉场内光强分布的数学模型,仿真计算了双光束、三光束、四光束干涉曝光情况下,入射光束存在角度偏差以及各入射光强不同时的干涉图样,并与理想状态的模拟结果进行对比.结果表明:光束入射角度偏差主要影响干涉图样的形状和周期;入射光的光强不同是降低图形对比度的主要因素.利用402nm波长激光光源进行多光束干涉光刻实验.设定激光器输出功率32mW,每两束光夹角为16°,通过控制曝光、显影工艺,双光束干涉光刻产生周期为1.4μm的光栅、点阵和孔阵结构,三光束干涉光刻产生周期为1.7μm的六边形图形阵列.该模型可为利用干涉光刻技术制备微细周期结构,提高光刻图形质量,提供一定的理论参考.     

波导耦合纳米光栅结构的光学滤波和角分辨调谐特性

利用干涉光刻技术制备了波导耦合纳米光栅结构,系统研究了其波导共振模式的角分辨调谐特性及其对光栅参数、入射光偏振特性的依赖关系,并作了相应的理论模拟.特别研究了光栅周期和厚度对波导共振模式角分辨调谐速率的影响.实验结果对于器件进一步应用于滤波、生物传感技术具有重要的指导意义. 关键词： 波导耦合光栅 干涉光刻 角分辨 调谐速率     

双尺度织构的激光光刻工艺

搭建了双光束激光干涉光刻系统和激光快速扫描系统。利用干涉光刻系统,实现了不同周期、不同深度、大面积的表面规则光栅织构的构筑。利用激光快速扫描器的二维扫描功能,通过控制激光功率和扫描速度,对曝光量和填充线条间距进行了优化。提出了两种双尺度复合织构的制备方法:一种是在激光快速扫描系统中对抗蚀剂表面分别进行x, y方向的扫描光刻,然后在干涉光刻系统中进行双光束干涉光刻;另一种是在激光干涉光刻系统中进行两次曝光,每次曝光的入射角不同。实验结果表明:这两种方法在制备双尺度复合织构方面具有快速、廉价、操作简易等优点。     

大面积金纳米线光栅的制备

利用激光干涉光刻和金纳米颗粒胶体溶液制备了宽度在100 nm以下且总面积达到平方厘米量级的金纳米线光栅结构.制备过程中,首先在表面镀有厚度约为200 nm的铟锡氧化物薄膜的面积为1 cm×1 cm的玻璃基片表面旋涂光刻胶,然后利用紫外激光干涉光刻制备光刻胶纳米光栅结构.有效控制干涉光刻过程中的曝光量、显影时间,获得小占...     

复合Ag/SiO_2正弦光栅基底SERS特性分析

当前微流控表面增强拉曼散射(SERS)检测领域常用的贵金属纳米颗粒溶胶单位体积内热点区域数量有限且热点区域范围较小,而贵金属纳米三维阵列结构加工时间长,成本高昂并存在"记忆效应"。本文提出了集成到微流道的复合Ag/SiO_2正弦光栅SERS基底结构,可以利用激光干涉光刻技术进行制备,无需预制掩膜版,可实现大面积、低成本SERS基底简易快速制备。利用严格耦合波分析方法(RCWA)建立了复合正弦光栅表面电场增强数学评估模型,推导了表面等离子体共振(SPP)耦合吸收率数学模型,分析了入射光、复合正弦光栅结构与外界环境介电常数的优化匹配关系,得到了入射光785 nm条件下的最佳复合正弦光栅结构。通过制备加工并实验验证了复合正弦光栅的SERS性能,SERS增强因子(EF)能够达到10~4。     

基于傅里叶变换光学系统的动态多光束干涉光刻

变参量微纳结构在二维平面内交叉、分段排布可以实现超表面器件的多路复用和多功能集成。为实现交叉、分段变参量微纳结构的干涉制备,提出了孔径光阑与相位元件联合调制的傅里叶变换光学系统。利用透镜的傅里叶变换特性和相位元件衍射光线的几何传播特性,阐明了傅里叶成像面上交叉、分段分布的多干涉光场的生成方法与调控规律。同时,针对目标分布的变参量微纳结构,反演设计了多像素孔径光阑与基于光栅和变参量光栅的相位元件,实验获得了交叉、分段分布的多干涉光场。将多干涉光场与微缩投影结合可制备分段排布的纳米光栅。将动态调控的多干涉光场分时复用可制备分段排布的变参量纳米光栅。     

分形图形与激光全息防伪技术

利用分形图形具有无限可分和比例尺度上的自相似的特征以及可以产生无限变量重复码的特点，通过计算机控制激光双光束干涉光刻成点阵全息光栅，从而形成数字像素全息图．构造出分形图形的迭代函数系统框架，形成丰富多彩，变化多端的分形图形，以此对点阵全息光栅编码，光刻成分形数字像素全息图．     

具有存储功能的衍射图像光刻系统的研制

研制了一种在衍射光变图像器件上进行信息存储的新型数字化激光光刻系统。采用空间光调制器作图形自动输入,双远心投影成像系统在光刻记录面上缩微图形。通过光栅干涉光学头对记录面上的微图形进行干涉调制,使微图形上产生干涉条纹,条纹空间频率范围为500-1200lp／mm。在光刻胶干版上的存储实验表明,在衍射光变图像上的单角度存储信息密度大于3．7Mbit／cm^2。改变干涉条纹取向、条纹间隔和需要存储的图形,光刻系统可实现信息的旋转复用存储。上述光刻系统将会在防伪和衍射光变图像器件制造领域有良好应用。     

Arbitrary structuring of two-dimensional photonic crystals by use of phase-only Fourier gratings

The computer-generated holography technique is applied to the structuring of two-dimensional (2D) photonic crystals with inherently embedded arbitrary defects. The technique uses phase-only Fourier gratings as a generator of spot arrays in the focal plane, such that a single exposure produces a 2D array of focused spots with desired defects or modifications in the lattice structure. We demonstrate several types of large-area 2D lattice structures with square, hexagonal, or hybrid lattices embedded with point and (or) line defects. Scanning the Fourier plane in the depth direction throughout multiphoton polymerization media allows 3D lattices with stacked defect layers to be formed.     

Study on wetting properties of periodical nanopatterns by a combinative technique of photolithography and laser interference lithography

This study presents the wetting properties, including hydrophilicity, hydrophobicity and anisotropic behavior, of water droplets on the silicon wafer surface with periodical nanopatterns and hierarchical structures. This study fabricates one- and two-dimensional periodical nanopatterns using laser interference lithography (LIL). The fabrication of hierarchical structures was effectively achieved by combining photolithography and LIL techniques. Unlike conventional fabrication methods, the LIL technique is mainly used to control the large-area design of periodical nanopatterns in this study. The minimum feature size for each nanopattern is 100 nm. This study shows that the wetting behavior of one-dimensional, two-dimensional, and hierarchical patterns can be obtained, benefiting the development of surface engineering for microfluidic systems.     

Ge quantum dot molecules and crystals: Preparation and properties

Templated self-organization has been used to prepare two-dimensional arrays as well as three-dimensional quantum dot crystals (QDC) containing Ge dots in a Si host crystal. Si(1 0 0) substrates have been patterned with two-dimensional hole gratings using extreme ultra-violet interference lithography (EUV-IL) and reactive ion etching. The EUV-IL was realized by multiple beam diffraction using Cr gratings on SiN_x membranes fabricated by e-beam lithography. Si/Ge overgrowth was performed by molecular beam epitaxy. The impact of the microscopic shape and size of the prepattern using the mask design and the EUV-IL exposure dose as parameters on the Ge dot nucleation has been studied with atomic force microscopy, transmission electron microscopy and photoluminescence measurements. Adjusting the growth parameters in multiple layer deposition the initial two-dimensional configuration was transferred into three-dimensional QDC.     

Self-assembling of gold nanoparticles in one, two, and three dimensions

In the present work, we report the growth of ordered arrays of gold nanoparticles passivated with n-alkylthiol molecules using crystallization in toluene vapor. We kept constant the average particle size and the length of the passivating molecule (1-dodecanethiol). The temperature and time of growth were varied. We show that in the initial stages of the growth, nano-chains of particles are produced. These nano-chains aggregate to form two-dimensional arrays. In the initial stages the nano-chains form a two-dimensional square lattice which then relaxes to a close-packed structure. In latter stages of growth a three-dimensional supercrystal is produced. It is found that the packing of nanoparticles corresponds to an average FCC lattice. However, large variations on the local parameters of the lattice are observed. Near the edges of the supercrystal the anomalous packing reported by Zanchet et al. [20] and Fink et al. [21] was observed. The energy of the observed structures is analyzed using molecular dynamics simulation. It is concluded that using the vapor growth method, it is possible to produce controlled ordered structures from one to three dimensions. Received: 24 February 2000 / Accepted: 28 March 2000 / Published online: 13 July 2000     

二维光栅与周期性缝隙阵列组合薄膜结构的杂散光抑制

传统方格型二维光栅与周期性缝隙阵列的组合薄膜结构具有雷达和光学波段双带通的电磁特性. 但由于其杂散光能量集中分布而严重制约它在高精度探测以及成像领域中的应用. 本文提出了一种全新的组合薄膜结构, 即由满足一定约束条件的圆孔型二维光栅和十字缝隙阵列构成. 基于Fraunhofer衍射理论建立组合薄膜结构标量衍射模型, 通过对比两种组合薄膜结构的衍射光分布, 理论分析与实验测试均表明: 圆孔型光栅与十字缝隙阵列组合薄膜结构不仅能够提高其光学透过率, 而且还使其杂散光分布均匀, 降低了其杂散光总比率, 从而有效抑制杂散光, 进一步增强了二维光栅与周期性缝隙阵列组合薄膜结构在实际光学系统中的可靠性. 关键词： 二维光栅 组合薄膜结构 衍射光强 杂散光     

Flame four-dimensional deflection tomography with compressed-sensing-revision reconstruction

Deflection tomography with limited angle projections was investigated to visualize a premixed flame. A projection sampling system for deflection tomography was used to obtain chronological deflectogram arrays at six view angles with only a pair of gratings. A new iterative reconstruction algorithm with deflection angle compressed-sensing revision was developed to improve reconstruction-distribution quality from incomplete projection data. Numerical simulation and error analysis provided a good indication of algorithm precision and convergence. In the experiment, 150 fringes were processed, and temperature distributions in 20 cross-sections were reconstructed from projection data in four instants. Four-dimensional flame structures and temperature distributions in the flame interior were visualized using the visualization toolkit. The experimental reconstruction was then compared with the result obtained from computational fluid dynamic analysis.     

Ensemble expectations for structures on two-dimensional lattices

Expressions are obtained for the limiting behavior of ensemble expectations, as functions of coverage, of the number of simultaneous occurrences of various structures when indistinguishable single particles are arranged on a two-dimensional lattice. For the general expressions obtained no restrictions are placed on the geometrical nature of the lattice. Averages for specific geometrical arrays, such as rectangular and hexagonal arrays, may be calculated directly from the general results.     

Fabrication of gold nano-particle arrays using two-dimensional templates from holographic lithography

We report a simple and cost effective method to fabricate regular metallic particle arrays over large areas with good regularity by using holographic lithography interference for the study of localized surface plasmon. Samples of disk-shaped gold nano-particles arranged in square arrays with lattice spacing ranging from 300 nm to 600 nm were successfully fabricated on glass substrates first by sputtering a thin gold layer onto two-dimensional photoresist templates of hole arrays in square lattice obtained by the holographic method and then removing the photoresist by a lift-off procedure. The plasmonic resonance of the gold nano-particle arrays due to the change of morphology by thermal annealing was studied. The disk-shaped gold nano-particles were found to become more round shaped upon heating and blue shift of the extinction plasmonic band was observed. The results were explained with model calculations using spheroidal particles.     

High-power laser beam shaping by inseparable two-dimensional binary-phase gratings for surface modification of stamping dies

For surface modification of stamping dies, an inseparable two-dimensional binary-phase gratings is introduced to implement the wavefront transformation of high-power laser beams. The design and fabrication of the gratings are described in detail. Two-dimensional even sampling encoding scheme is adopted to overcome the limitations of conventional Dammann grating in the design of two-dimensional output patterns. High diffractive efficiency (>70%) can be achieved through the transformation of the Gaussian laser beam into several kinds of two-dimensional arrays in focal plan. The application of the binary-phase gratings in the laser surface modification of ductile iron is investigated, and the results show that the hardness and the wear resistance of the sample surface were improved significantly by using the binary-phase gratings.     

Terahertz demonstrations of effectively two-dimensional photonic bandgap structures

We demonstrate effectively two-dimensional (2D) terahertz (THz) photonic bandgap (PBG) structures for transverse electromagnetic (TEM) mode propagation within metal parallel plate waveguides (PPWG). The 2D-PBG structures consisting of square arrays of dielectric cylinders were characterized by THz time-domain spectroscopy (THz-TDS). THz photonic bandgaps were observed, as determined by the 160 mum lattice constant, the 65 mum diameter, and the dielectric constant of the cylinders. The experimental measurements were fitted with excellent agreement to 2D theory, confirming that for TEM mode propagation, effectively 2D propagation experiments can be achieved within the bounded space of the PPWG.