| Research Abstract |
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.
|
