External cavity diode lasers with E-beam written silicon diffraction gratings

Performance of external cavity diode lasers with silicon gratings produced by E-beam writing and subsequent reactive ion etching is described. Optical amplifiers used in the experiments were based on single quantum well heterostructures grown by molecular beam epitaxy. The lasers were set up in the Littrow configuration and have been designed to allow for wavelength tuning in the range centred at 960 nm.     

A model of knowledge activation and insight in problem solving

This article presents a model of insight that offers predictions on how and when insights are likely to occur as an individual solves problems. This model is based on a fundamental trade‐off between the conscious cognition that underlies how people decide among alternatives and the unconscious cognition that underlies insight. I argue that the attention controls how much thought (i.e., knowledge activation) goes to conscious cognition, and whatever activation is left over will go to finding an insight. I validate this model by replicating the common pattern of insight in problem solving (preparation—impasse—incubation—verification). The model implies that 1) one should be able to increase the frequency of insight by lessening the demand for conscious cognition, 2) impasse is not necessary for insight, and 3) incubation time increases if a person engages in any activity with a high demand on attention. Understanding how insight occurs during problem solving provides practical suggestions to make people and groups more creative and innovative; it also provides avenues for future research on the cognitive dynamics of insight. © 2004 Wiley Periodicals, Inc. Complexity 9: 17–24, 2004     

浅议高等数学的教学理念

本文根据目前高等数学教学的现状，提出了更新教师的教学理念，教学过程融入现代数学思想的一些建议．     

关于开放实验教学的研究和设想

本对物理实验课开放实验教学的意义和可行性做了研究和探讨，并以分层次教学为指导思想，提出了如何实施开放实验教学的设想。     

Rapid Prototyping of Sensors and Conductive Elements by Day‐to‐Day Writing Tools and Emerging Manufacturing Technologies

The growing demand for low cost and easy to use analytical devices requires the development of reliable and rapid deposition strategies suitable for changing easily planned designs and applicable to a wide range of materials for assembling conductive tracks and sensitive elements. Further important challenges to be pursued are the possibility of using readily available instrumentation and reducing power consumption and hazardous chemical waste. This review provides an overview of the use of portable day‐to‐day writing tools, such as pencils and pens, for the rapid and on‐demand deposition of conductive patterns on different substrates, with particular emphasis on the assembly of “Do It Yourself” sensors. Moreover, layer‐by‐layer deposition of simple or even complex three dimensional (3D) circuits, resorting to pressure driven extrusion of conductive filaments is considered. Future perspectives and potentiality of these emerging technologies for assembling sensors are also explored.     

Three‐dimensional optical laser lithography beyond the diffraction limit

Direct laser writing has become a versatile and routine tool for the mask‐free fabrication of polymer structures with lateral linewidths down to less than 100 nm. In contrast to its planar counterpart, electron‐beam lithography, direct laser writing also allows for the making of three‐dimensional structures. However, its spatial resolution has been restricted by diffraction. Clearly, linewidths and resolutions on the scale of few tens of nanometers and below are highly desirable for various applications in nanotechnology. In visible‐light far‐field fluorescence microscopy, the concept of stimulated emission depletion (STED) introduced in 1994 has led to spectacular record resolutions down to 5.6 nm in 2009. This review addresses approaches aiming at translating this success in optical microscopy to optical lithography. After explaining basic principles and limitations, possible depletion mechanisms and recent lithography experiments by various groups are summarized. Today, Abbe's diffraction barrier as well as the generalized two‐photon Sparrow criterion have been broken in far‐field optical lithography. For further future progress in resolution, the development of novel tailored photoresists in combination with attractive laser sources is of utmost importance.     

试论徐光宪的科学思想与科学方法

徐光宪对科学理论合理性的评价是从理论概念与物质结构要素的对应、科学理论解释性的强弱等方面进行的。他认为化学学科有独特性,化学反应以及与化学反应相关的分子结构与性质研究,是化学独特的研究对象与问题领域,化学在该领域形成了自己的理论,并不能被还原为物理学。徐光宪用自己的多维分类法对知识进行分类,提出分类的目的是为了做出发现,在研究中亦利用分类进行思维和方法创新。用数学化的方法实现化学研究的精确性,借用模型抽象理论、简化研究程序,综合使用多种仪器设备、将旧仪器引入新领域、拓展仪器的功能,徐光宪为自己的研究需要改进和发明新工具的同时,还为其它研究者提供了便捷有效的工具。     

Functionalisation of cholesteric liquid crystals by direct laser writing

Cholesteric liquid crystals selectively reflect circularly polarised light with the same handedness as the helix. Because of their sensitivity to external stimuli, such as heat and electrical fields, various applications utilising their tunability have been proposed. Tuning is usually performed in the bulk, meaning that cholesteric liquid crystals usually possess a single pitch throughout the medium. However, when the helical structure is locally modulated, different optical properties arise, such as tunable photonic defect modes and multiple reflection bands. Here we show a technique to locally modulate the helical structure of cholesteric liquid crystals on a submicron scale, based on two-photon excitation direct laser lithography. Two examples of cholesteric liquid crystal structures with modulated helical structures will be presented.     

用于蓝光(405nm)激光直写的聚乙烯醇/银纳米复合材料薄膜的制备

利用紫外光诱导还原金属前躯体硝酸银(AgNO3),直接在聚乙烯醇(PVA)薄膜中生长银纳米颗粒,成功制备出PVA/Ag纳米复合材料薄膜。利用紫外-可见吸收光谱分析了银离子浓度、紫外光辐照功率和辐照时间对薄膜光谱的影响趋势。通过优化硝酸银浓度、辐照条件来调节薄膜中银纳米颗粒的尺寸和空间分布密度,成功地将此复合薄膜的等离子共振吸收峰位调节为406nm,并用于蓝光(405nm)激光直写光刻。扫描电子显微镜(SEM)观察表明,该材料中纳米颗粒分布均匀,粒径分布较窄;X射线光电子谱(XPS)证实了合成的纳米颗粒为单质银;原子力显微镜(AFM)分析显示薄膜光刻后获得了表面清晰、光滑、规整的图形。