【作者】 柏菲；

【导师】 简国树；

【作者基本信息】 大连理工大学 ， 光学， 2005， 硕士

【摘要】 扫描近场光学显微镜(SNOM)是八十年代发展起来的亚波长量级的扫描探针型显微镜,能对纳米尺度的样品成像,且具有光学观察无损探测的特点,可观察活的生物样品,保持细胞活性,在透明材料,生物、医学研究中都有应用。 光子扫描隧道显微镜(PSTM)是其中的一种,在PSTM的物理模型中,平行入射的激光束以超过全内反射临界角为入射角照射样品台,在样品表面上方将产生隐失波。当光纤探头进入样品表面隐失波区域时产生扰动,将产生光子隧道效应,即探针尖将隐失场光耦合入光纤,转换为可传输光被收集,从而获得携带样品表面形貌和光学性质的信息。 整个过程涉及到光纤探针和样品的散射场相互作用,使得过程分析非常复杂,有必要进行数值模拟。其中,时域有限差分法是各种数值模拟方法中相对简捷有效的方法,在近场光学数值模拟中有着广泛的应用。目前主要应用于扫描近场光学显微镜,在光子扫描隧道显微镜中的应用还有一定的局限,尤其是有色散介质探针的PSTM成像数值模拟,很少有文献深入讨论。 探针形状各种参数的优化在扫描隧道显微镜的分辨率的提高中起关键作用。为了研究不同光纤探针类型的光子扫描隧道显微镜的成像特征,在课题组以前研究的基础上,本文引入了色散介质Drude模型,考虑探针和样品的相互作用,用三维时域有限差分法模拟了探针距离尖项一定高度截面处的玻印亭矢量分布。所研究的探针类型包括不镀膜光纤探针、尖端带金属颗粒光纤探针、镀膜孔径光纤探针以及镀膜尖端带金属颗粒光纤探针。此外,还分析了不同参数变化对成像分辨率和灵敏度的影响,得出了一些有意义的结果。更多还原

【Abstract】 Scanning Near-field Optical Microscope (SNOM) is a near-field optical microscope that can measure local optical properties with high resolution beyond the diffraction limit, It can detect the sample harmless, study the biology alive, and even the translucent materials. So it is applied widely in lots of fields such as studies in biology and medicine in recent years.Photon Scanning Tunneling Microscope (PSTM) is one kind of SNOM, in the model of which, the surface evanescent wave, which is generated under total internal reflection condition, excites the sample to form a scattering field, then the near-field is detected by the optical fiber probe tip, in which it is transformed to propagating wave.The whole process refers to the scattering fields of the sample and fiber probe and the interaction between them, which make the analyses of the process more complicate. So, it is necessary to simulate the process numerically. In all kinds of the simulation methods, the Finite-Difference Time-Domain (FDTD) method is a simple and effective simulate algorithm which applied in the numerical simulation of the scanning near-field optical microscope (SNOM). But it is hardly applied in the study about the different types of the PSTM metallic fiber probe imaging.Based on former study, in the collection mode, the optical resolution is mainly determined by the shape of the probe. In this paper, considering the interaction of the probe and sample, we test the Pointing Vector distribution in a section at a certain height from the probe tip with equivalent incident wave method of the three dimensional FDTD and study the different imaging conditions of the four types of probes: bare fiber probe, metal coated aperture fiber probe, total metal-coated fiber probe, the one with metal particle on the tip and the metal-coated probe with a nanometric metallic pyramid in the tip. Furthermore, the influences of the parameters’ changes in each kind of probe tip on the imaging are investigated and compared. These results we get are valuable for the selection of the probe parameters of the PSTM.更多还原