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

为了实现无源纳米器件，将表面等离子体激元激发在镀在玻璃板上的50 nm厚的银薄膜上。发现了镀层厚度均匀的最佳条件，即在银和玻璃之间夹覆一层锗膜可以提高镀层的均匀性。光掩膜法也被开发出来以实现银膜的锐利边缘。结果，边缘的清晰度提高了30倍。提出了将染料分子固定在针尖直径小于100 nm的锐化光纤探针上的方法，实现了具有光学功能的探针针尖。利用这些染料分子的荧光进行成像实验，证实了该探针在近场光学显微镜中的应用，在超平面蓝宝石衬底上生长出铌酸锂（LN）纳米晶体，即典型的非线性光学晶体，实现了纳米区域的频率转换。对它们的特性进行了评价，特别是对二代荧光进行了评价。用近场光学显微镜测量了生长的LN晶体（30nm × 20nm）的形貌，其空间分辨率高达几nm。进一步分析了图像对入射光偏振态的依赖关系，与理论结果吻合较好。将脉冲宽度为100fs（波长为800nm）的脉冲激光照射到LN晶体上，进行二次谐波产生实验。通过光子计数法测量二次谐波信号，确定了每个LN晶体提供1位光学功能的能力。通过本文的实验和理论研究，为实现纳米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.