Realization of nanometric optical functional devicesusing evanescentlignt localized in a subwavelendth three dimensional space

为了实现被动纳米器件，在镀膜于玻璃板上的厚度为50 nm的银薄膜上激发表面等离子体激元。得到了厚度均匀的最佳镀膜条件，即在银和玻璃之间夹杂一层金膜可提高镀膜的均匀性。还开发了光掩模法以实现银片的锋利边缘。结果，边缘的锐度提高了30倍。发展了一种将染料分子固定在尖端直径小于100 nm的锐化光纤探针上的方法，以实现光学功能探针尖端。利用这些染料分子的荧光进行了成像实验，证实了该探针在近场光学显微镜中的应用，在超平蓝宝石衬底上生长了典型的非线性光学晶体--铌酸锂纳米晶体，实现了纳米范围内的频率转换。对它们的特性进行了评价，特别是对第二代二次谐波进行了评价。用近场光学显微镜测量了生长的LN晶体(30nmx20 Nm)的轮廓，确定了高达几nm的空间分辨率。此外，还对入射光偏振态对像的依赖性进行了评估，得到了与理论结果相一致的结果。用脉冲宽度为100fs(波长800 nm)的脉冲激光照射LN晶体，进行了二次谐波产生实验。利用光子计数法测量了二次谐波信号，通过实验和理论研究，证实了为每个LN晶体提供1bit光学功能的能力，为实现纳米级光学功能器件奠定了基础。

To realize a passive nanometric device, surface plasmon was excited on a silver thin film with 50 nm thickness which was coated on a glass plate. Optimum condition for coating was found for homogeneous thickness, i.e., we found that the homogeniety was increased by sandwitching a gemanium film between silver and glass. Photomask method was also developedto realize a sharp edge of the silver tilm. As a result, sharpness of the edge was increased 30 times. Method of fixing dyemolecules on a sharpenedfiberprobe (the tip diameterless than 100 nm) was developedto realize a optically functional probe tip. Imaging experiment was carried out by using fluorescence from these dye molecules, by which utility of this probe to the near-field optical microscopy was confirmed Nano-crystals of Lithium niobate (LN), i.e., typical nonlinear optical crystals, were grown on an ultraflat sapphire substrate to realize frequency conversion in a nanometric region. Evaluation of their characteristics, and especially second harominc generation, were carried out. Profiles of grown LN crystals (30nmx20nm) were measured by a near-field optical microscope, by which spatial resolution as high as several nm was confirmed. Further, image depencency on the polarization state of the incidentlight was evaluated, and good agreement with the theoretical result was obtained. By irradiating the pulsedlaser light with 100fs pulse width (800nm wavelength) to the LN crystals, experiment of secondharmonics generation was carried out. Secondharmonic signal was measured by photon counting method, by which capability of offering 1-bit optical function to each LN crystal was confirmed Due to the experimental and theoretical studies carried out here, fundamentals for realizing nanometric optical functional devices were estabilished.