光学微透镜阵列模压成形研究进展与展望

光学微透镜阵列在光学系统中的应用广泛,需求量大,而玻璃模压成形技术是最高效的微透镜阵列量产加工方法,具有精度高,一致性好,生产成本低等特点,有重要的应用研究价值。本文介绍了光学微透镜阵列的设计原理,模具制造技术,模压成形技术及相应检测技术;重点介绍了微透镜阵列模压成形试验与有限元仿真研究的最新进展;最后对微透镜模压成形发展前景进行了展望,包括微透镜阵列模压材料,模具表面镀层技术及超声复合加工技术在微透镜阵列模压成形中的应用等。     

微透镜阵列光学相控阵扫描技术研究进展

光学相控阵光束扫描技术在激光雷达、空间光通信和光开关等领域拥有巨大的应用潜力。微透镜阵列光学相控阵可以通过微透镜阵列间μm量级的相对位移同时对多个出射光束的二维倾斜相位进行调制,从而实现大角度二维光束扫描,具有出射口径大、结构简单、体积小、微惯性、多功能等优点。首先介绍了微透镜阵列光学相控阵的扫描原理,之后对微透镜阵列光学相控阵国内外的发展现状、应用和现阶段存在的问题进行了阐述,最后对微透镜阵列光学相控阵的发展趋势进行了展望。

     

Fabrication of long hexagonal micro-lens array by applying gray-scale lithography in micro-replication process

A hexagonal micro-lens (HML) array with long aspect ratio of 3.3:1 designed for beam shaping was fabricated by applying gray-scale lithography in micro-replication process. The gray-scale lithography process was employed in this study to obtain unity curvature and to maximize filling factor of the lens array. Precision micro-replication process was applied to duplicate HML on a flexible polyethylene terphthalate (PET) substrate by UV-forming process. The geometry character of obtained HML was inspected and the shape of HML is very close to the designed specification. The optical performance was also investigated. It was found that the incident Gauss beam was diversified differently at short and long axis. The beam full widths at the half maximum (FWHM) at short axis and long axis directions through the HML are 0.61 μm and 0.25 μm, respectively. Hence, the beam divergent ratio at long and short axis of 2.44:1 was achieved.     

Design and fabrication of a negative microlens array

An operation model of a negative microlens array is demonstrated. The array consists of two kinds of materials with different refractive indices. First of all, a positive microlens array with 256×256 elements serving as a pattern is fabricated by argon ion beam etching on the quartz. The diameter and average corona height of the element are 28 and 0.638 μm, respectively. The spacing between two neighboring elements is 2 μm. In the second phase, after being coated by epoxy, the positive microlens array pattern is spun and baked, leading to a complex negative microlens array. Surface stylus measurement shows that the surface of the positive quartz microlens array is smooth and uniform. Focal length measurement of the negative microlens array indicates that the focal length region with −731±3 μm is in good agreement with the theoretical calculation value of −729 μm.     

Fabrication of a 256-bits organic memory by soft x-ray lithography

This paper reports a procedure of soft x-ray lithography for the fabrication of organic crossbar structure. Electron beam lithography is employed to fabricate the mask for soft x-ray lithography, with direct writing technology to lithograph positive resist, polymethyl methacrylate on the polyimide film. Then Au is electroplated on the polyimide film. Hard contact mode exposure is used in x-ray lithography to transfer the graph from the mask to the wafer. The 256-bits organic memory is achieved with the critical dimension of 250~nm.     

飞秒平顶光束经微透镜阵列在熔融石英中的成丝及其超连续辐射

实验研究了平顶激光光束经微透镜阵列在熔融石英中成丝的演化以及超连续辐射的产生,并进一步与高斯光束的成丝和超连续辐射进行了对比研究.分别对这两种光束的多丝传输进行了横向和纵向成像.结果表明,使用平顶光束可以获得更为均匀的多丝分布,成丝的起点也更为一致;尤其重要的是,相对于高斯光束,平顶光束可以使用更高的入射激光脉冲能量而不会造成介质的损伤,从而可以获得更高脉冲能量和更高转换效率的超连续辐射.     

Effect of chromium interlayer deposition on periodic silver nanoparticle array structure fabricated by nanosphere lithography

Effect of chromium interlayer deposition on 2-dimensional, periodic silver nanoparticle array structure was systematically investigated. The silver nanoparticle array was fabricated by nanosphere lithography with assembled polystyrene nanospheres being as a deposition mask. The chromium interlayer was deposited by thermal evaporation either on the nanosphere mask or directly on the silicon substrate. The structures of the achieved silver nanoparticle arrays were characterized by scanning electron microscope and were compared with that of silver nanoparticle array without the interlayer. With analysis of the anomalies among the structures the critical role of the interlayer in the periodic nanoparticle array fabrication was revealed.     

Fabrication and design of various dimensions of multi-step ashperical microlens arrays for OLED package

An optical film with aspherical microlens array (A-MLA) by using multi-step lithography process for an OLED (Organic Light-Emitting Diode) package is fabricated, by which method the luminance of OLEDs can be enhanced. The method of design and fabrication of an A-MLA is explored in this study. In the design process, various parameters of an A-MLA such as curved profiles, layout template and dimensions of microlens are analyzed and characterized. Curved profiles include hyperbola, parabola, ellipse and sphere; and layout templates include square, hexagon, triangle and tangential circle. The profile of the A-MLA was determined by using a commercial optical simulation software, FRED. Based on the simulated result, a film with an A-MLA was fabricated using the LIGA-like (Lithographie Galvanoformung Abformung, LIGA) process, including lithography, sputtering, micro-molding with PDMS (Polydimethylsiloxane) and UV (Ultraviolet)-cured technology. The major challenge to this process is to use JSR-126N negative thick photoresist to manufacture an approximate A-MLA optical film with multi-step lithography method. Finally, the films with A-MLAs are attached to an OLED to measure their optical-electric properties. The effectsof A-MLA optical films on OLED luminance are analyzed. In addition, the measured results are compared with simulated ones. They show good agreement with each other.     

有序金纳米颗粒阵列的制备及光吸收特性研究

采用纳米球刻蚀技术中漂移法在玻璃基片上制备较大 面积不同直径的聚苯乙烯小球掩模板, 采用磁控溅射技术在掩模板上沉积不同厚度的金薄膜, 去除聚苯乙烯小球后, 通过扫描电子显微镜观察到周期排列的三角状金纳米颗粒点阵. 通过紫外-可见分光光度计测试所制备样品的光吸收特性, 发现表面等离子体共振峰随粒径增大发生红移, 随金纳米颗粒高度增加发生蓝移. 基于Mie理论, 利用Matlab软件编程对不同粒径的金阵列光吸收特性进行理论模拟, 并与实验结果进行对比. 关键词： 纳米球刻蚀 金纳米颗粒阵列 表面等离子体共振     

Fabrication of structures with tunable morphologies and sizes by soft molding

This paper presents a simple and versatile patterning method to fabricate polymer patterns with different morphologies and sizes by utilizing soft molding. When a patterned elastomeric stamp was placed on the polymer solution dropped on the substrate, the polymer solution will fill into the grooves of the stamp under capillary force. Through the modulation of the polymer concentration, it is possible to produce highly regular and reproducible polymer patterns with tunable morphologies and sizes using the same microscopic patterned mold. The gained polymer patterns can be further transferred to produce second-generation stamps.     

凹面相控阵聚焦声场在液固界面上的反射和折射

开展了凹面线性相控阵列辐射声场在液固界面上的反射和折射特性研究,利用射线近似方法,得到了凹面相控阵聚焦声场在液固界面上反射和折射后的声场渐近解析表达式,对声波在液固曲面上的反射和折射声场进行了分析和讨论. 利用这个解析表达式,对凹面线性聚焦声场在液固平界面和液固圆柱界面情况下固体中折射纵波和折射横波的相控阵声场进行了分析和讨论,发现凹面线阵声场在液固圆柱界面下比液固平界面具有更好的聚焦效果. 关键词： 凹面阵列 超声相控阵 反射与折射     

Fabrication of double quantum dots by combining afm and e-beam lithography

In recent years several attempts have been made to fabricate coupled quantum dots as a crucial element of quantum computing devices. One important challenge is to achieve a reliable control of the interdot tunneling. For this purpose we have combined direct nanolithography by local anodic oxidation (LAO) with standard electron-beam lithography. LAO is used to produce parallel double quantum dots. Additional metallic split gates are responsible for the control of the interdot coupling. We describe our fabrication scheme and demonstrate the function in low-temperature transport measurements.     

纳米球刻蚀法制备的二维有序的CdS纳米阵列及其光学性质的研究

采用纳米球刻蚀(nanosphere lithography)技术,以自组装的聚苯乙烯纳米小球(polystyrene,PS小球)的单层膜为掩模,制备出二维有序的CdS纳米阵列.利用扫描电子显微镜(SEM)对样品结构进行了表征,用紫外—可见分光光度计对样品光学性质进行了分析.结果表明：制备的二维CdS纳米阵列是高度有序的,且与作为掩模的纳米小球的原始尺寸及排布结构一致;禁带宽度为2.60eV,相对于体材料的2.42eV,向短波长蓝移了0.18eV,表现出CdS材料在纳米结构点阵中的量子尺寸效应;CdS纳米 关键词： 纳米球刻蚀 二维CdS纳米有序阵列     

Fabrication of NdFeB microstructures using a silicon molding technique for NdFeB/Ta multilayered films and NdFeB magnetic powder

The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-μm-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3 T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Using a silicon molding technique complemented by a lift-off process, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 μm are filled by a mixture of magnetic powder and wax powder. The B-H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T.     

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.     

Fabrication and magnetic property of binary Co-Ni nanowire array by alternating current electrodeposition

Ordered binary Co-Ni nanowire arrays with different components have successfully been fabricated by ac electrodeposition. The as-obtained nanowires exhibit a diameter of about 49.2 nm and aspect ratio of more than 30. A highly preferential orientation of the Co-Ni nanowires has been obtained by XRD. The magnetic properties of Co-Ni nanowire arrays determined by VSM are as the function of the Co-Ni components. The maximum value of coercivities perpendicular to the array is 2073 Oe. However, the magnetic properties of such nanowire arrays exhibited a bad thermal stability at the medium temperature of 200 °C.     

Fabrication of high‐aspect‐ratio Fresnel zone plates by e‐beam lithography and electroplating

The fabrication of gold Fresnel zone plates, by a combination of e‐beam lithography and electrodeposition, with a 30 nm outermost zone width and a 450 nm‐thick structure is described. The e‐beam lithography process was implemented with a careful evaluation of applied dosage, tests of different bake‐out temperatures and durations for the photoresist, and the use of a developer without methylisobutylketone. Electrodeposition with a pulsed current mode and with a specially designed apparatus produced the desired high‐aspect‐ratio nanostructures. The fabricated zone plates were examined by electron microscopy and their performances were assessed using a transmission X‐ray microscope. The results specifically demonstrated an image resolution of 40 nm.     

Au诱导形成有序Si纳米孔阵列及其应用

以自组装聚苯乙烯小球(PS)单层膜为掩膜,利用Au对Si表面的催化氧化作用以及KOH溶液对单晶Si的各向异性腐蚀特性,在Si(100)面上制备了一系列尺寸小于100 nm有序可控的Si纳米孔阵列.扫描电镜(SEM)和原子力显微镜(AFM)等的测试结果显示:当PS小球溶液与甲醇溶液的体积比为9:11时,可形成大面积无缺陷的单层膜;但当体积比过大时,会导致类似双层膜结构的形成;而当体积比过小时,会诱导形成点缺陷和线缺陷.对PS小球及溅射Au处理过的Si晶片进行KOH溶液腐蚀,随着腐蚀时间变长,纳米孔的横向尺寸和深度增大,其形貌由圆形逐渐变为倒金字塔型,当腐蚀时间超过10 min,纳米孔阵列的有序性遭到破坏.采用离子束溅射技术在倒金字塔型纳米孔衬底上获得了有序Ge/Si纳米岛,而在圆形纳米孔衬底上获得了有序Ge/Si纳米环.进一步对有序Ge/Si纳米岛及纳米环的形成机理进行了解释.