纳米光学和生物单分子探测

纳米光学技术展示了纳米级探测本领，同时生物单分子探测所需要分辨尺度也是纳米数量级的，因此在生物单分子探测过程中，纳米光学发挥了巨大的作用．文章介绍了与生物单分子探测技术相关的纳米光学技术，包括量子近场光学探针技术、近场光学成像技术(包括扫描近场光学显微术及全内反射荧光显微术)和激光光钳测控技术及它们在生物单分子探测上的进展，从而在染色、成像、测控三个方面展示了纳米光学技术在生物方面的应用，并对其未来的发展方向进行了展望．     

纳米光子学的最新进展

论述了纳米光子学的最新进展，介绍了国际上的一些研究小组所做的关于纳米光子学的实验，包括纳米开关、近场光学探针技术、近场光化学气相沉积制备、基于等离子体激元波导实现的远近场能量的转换装置等内容，着重阐明实验原理和纳米制备技术中的一些关键问题。     

近场光学虚拟光探针的数值分析

虚拟光探针是基于近场光学隐失场干涉原理产生的一种非实体探针，可以应用于近场光学超高密度存储、纳米光刻、近场光学成像、光谱探测、纳米样品的近场光学操作等领域。本研究采用三维时间域有限差分（FDTD）方法对近场光学虚拟光探针的光场分布特性进行了数值模拟计算和比较，分析了孔的形状、大小及偏振态等因素对虚拟光探针光场分布的影响，研究结果表明虚拟光探针的通光效率较普通的纳米孔径光纤探针提高10^2-10^4倍；其光场分布的中间峰的半峰全宽（即虚拟光探针的尺寸）在一定距离范围内基本保持不变，从而可以解决近场光学系统中纳米间距控制的难题，避免光学头与介质的磁撞。优化虚拟光探针的设计参量能有效的抑制虚拟光探针中的旁瓣。文章还给出了应用虚拟探针实现高密度光存储的原理方案。     

非探针近场光学显微镜的成像实现

介绍一种非探针近场光学显微镜，并对它的图像实现过程及处理方法进行了讨论。该装置以阿达玛变换成像理论为基础，用纳米多孔编码板代替光纤探针获得了较高的光学信噪比。成像研究表明，该装置可对近场衰逝波分量进行有效探测并能实现超衍射极限成像，为近场光学探测研究提供了一种新的思路。     

基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像

本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路.     

基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像

本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路.     

反射式无孔径近场Raman研究(英文)

近场扫描光学显微技术与Raman光谱技术的结合能够在纳米尺度下提供化学 /结构信息 ,这对很多应用都是至关重要的 ,比如硅器件 ,纳米器件 ,量子点及生物样品单分子研究。本文报导了采用无孔径探针的近场Raman研究。我们的系统有两大特征 :1 近场Raman的增强是通过金属探针上的银镀层实现的 ,无需样品准备 ;2 系统在反射模式下工作 ,适用于任何样品。这两点对实际应用是至关重要的。我们首次在实际硅器件上用 1秒积分时间获得了 1维近场Raman映射和 2维近场Raman图象。我们首次展示了由于积分时间短 ,该技术可用于成象用途。因此 ,这是近场扫描Raman研究中的一次巨大进步。此外 ,我们系统中采用的金属探针可同时用于AFM及电学特性成象 ,比如电阻 ,电容 ,这些是器件应用中的重要参数。     

有孔探针近场拉曼光谱和成像技术进展

基于有孔探针SNOM的近场拉曼光谱和成像技术的出现使得拉曼光谱的分辨率突破了光学衍射极限,从而提供了一个有力的工具对样品亚波长尺度之下的化学信息进行表征。文章讨论了探针性质对实现近场拉曼光谱的影响,并全面地介绍了有孔探针近场拉曼光谱发展十余年来在纳米尺度化学分辨成像、液-液界面性质研究、微观层面解释SERS增强机理、图像化反映SERS热点分布等诸多领域的研究进展。     

影响近场光纤探针传输效率的若干因素

近场光学技术在高分辨率成像、光谱探测和纳米加工等领域有广泛应用,而光纤探针是其中一个关键部件.如何提高光纤探针的传输效率是近场光学技术应用中的一个重要问题.本文采用三维时域有限差分方法,计算了锥形有孔探针的传输效率,分析了锥角、针尖孔径、波长和金属层厚度等因素对光纤探针传输效率的影响,并比较了裸光纤探针和有金属涂层的光...     

激光扫描成像的纳米分辨技术

阐述一种新型激光近场扫成像系统──光子扫描隧道显微镜的实验成像显示技术。利用本系统对多种光学表面、聚合物、生物病毒等透光样品进行三维显微成像分析，获得了样品表面结构的纳米级空间化辨。     

Cloaked near-field scanning optical microscope tip for noninvasive near-field imaging

Near-field imaging is a well-established technique in biomedical measurements, since closer to the detail of interest it is possible to resolve subwavelength details otherwise unresolved by regular lenses. A near-field scanning optical microscope (NSOM) tip may indeed overcome the resolution limits of far-field optics, but its proximity inherently perturbs the measurement. Here, we apply the recent concept of a "cloaked sensor" to an NSOM device in collection mode, showing theoretically how a proper plasmonic cover applied to an NSOM tip may drastically improve its overall measurement capabilities.     

Recent progress of nano-technology with NSOM

Recent progress of nano-technology with near-field scanning optical microscope (NSOM) is surveyed in this article. We focus mainly on NSOM, nano-scale spectroscopy with NSOM, probe technology of NSOM, and study of nano-structured metallic surface with NSOM. First, we follow developments of aperture NSOM and apertureless NSOM, and then address progress of NSOM-combined spectroscopy which is so sufficiently advanced with apertureless NSOM technology to provide chemical information on length scales of a few nanometers. Recent achievement of nano-scale Raman and IR spectroscopy will be introduced. Finally, research on nano-optic elements using surface plasmon polariton with NSOM is introduced as an example of NSOM applications to nano-structured metallic surfaces.     

High-Contrast Imaging of Nano-Channels Using Reflection Near-Field Scanning Optical Microscope Enhanced by Optical Interference

We demonstrated a contrast enhancement in a near-field scanning optical microscope (NSOM) by optical interference with an aperture probe in reflection (illumination-collection) mode operation. We observed a NiO film deposited on a sapphire substrate and clearly visualized 2-nm-deep nano-channel structures on the surface of the film. The reflection NSOM enhanced by optical interference is quite a promising instrument for high-resolution optical detection and estimation of low-contrast nanostructures.     

Fabrication of high-quality fiber micro-probe for near-field optical microscope by laser-assisted melting and pulling method

The fiber micro-probe for near-field scanning optical microscope (NSOM) was fabricated using end-fixed laser-assisted melting and pulling method. The scanning electron microscope (SEM) observation showed that the fiber probes obtained by this method possessed small diameter of tip and large conic angle. The reproducibility came close to 70%. The effects of various fabrication parameters on probes were investigated, including laser power, pulling force, and the diameter of melting zone. The optimal processing conditions were derived based on the experiments and theoretical analysis. This research provides an alternative and advantageous method for fabrication of high-quality fiber probes.     

Effect of anisotropic strain on the crosshatch electrical activity in relaxed GeSi films

The physical origin of the crosshatch electrical activity in relaxed GeSi films was studied using a near-field scanning optical microscope (NSOM). The contrast and patterns in the near-field photocurrent images depend on the polarization direction of the NSOM light. These results rule out composition nonuniformity, junction depth variation, and scanning artifacts as dominant sources of the contrast. Numerical calculations show that local changes in band structure due to strain fields of the misfit dislocations are responsible for the experimental observations.     

Reducing Background Light Interaction in Near-Field Optical Microscopy Using Lateral and Vertical Probe-Dithering

We investigate the effectiveness of differential detection, which is a combination of probe-dithering and synchronous detection, in discriminating near-field light interaction from background light interaction in apertureless near-field optical microscopy (NSOM). The lateral differential NSOM with a photocantilever is more effective than the vertical differential detection, which does not always provide sufficient discrimination. The V-dithering-based lateral differential detection provides apertureless NSOM that can image the optical coupling between sample and probe dipoles, which is an interaction through near-field light.This paper was originally presented at the 5th International Conference on NEAR FIELD OPTICS and RELATED TECHNOLOGIES (NFO-5), which was held on December 6–10, 1998 at Coganoi Bay Hotel, Shirahama, Japan, in cooperation with the Japan Society of Applied Physics and Mombusho Grant-in Aid for Scientific Research on Priority Areas “Near-field Nano-optics” Project, sponsored by Japan Society for the Promotion of Science.     

A resonance tracking method for stable operation of a near-field scanning optical microscope in liquid environment

We report on the novel design of the near-field scanning optical microscope (NSOM) which operates in liquid environment. A resonance tracking digital scanning method is applied to compensate the resonance shift due to the evaporation of the liquid in the atmospheric pressure. By this method, stable operation of NSOM system is demonstrated by showing topographic images of the metallic grating embedded in liquid environment.     

10 nm Spatial Resolution Fluorescence Imaging of Single Molecules by Near-Field Scanning Optical Microscopy Using a Tiny Aperture Probe

We demonstrate high-resolution fluorescence imaging of single molecules using near-field scanning optical microscopy (NSOM) with a tiny aperture probe for two different wavelengths in visible range in the illumination mode of operation. The spatial resolutions obtained at both excitation wavelengths were almost the same and the highest resolution realized was about 10 nm. To discuss the achievable resolution in aperture NSOM, we also employed a computer simulation by the finite-difference time-domain method for various aperture sizes and wavelengths. The resolution of 10 nm is predicted to be contributed by the single peak of localized near-field light around the rim of the aperture.     

一种高透过率光纤探针的制作

本文介绍了一种用于近场扫描光学显微镜(NSOM)中的高透过率光纤探针的制作方法。采用缓冲氢氟酸腐蚀低掺杂的普通单模石英光纤,选取适当比例的腐蚀液,可以得到直径、圆锥角均十分理想的针尖。这种方法不需要高掺杂的特殊光纤或是采用先熔拉后腐蚀的复合工艺。针尖经过镀膜后经测量为针尖直径100nm、透过率5.5×10^-4.