Nonliner optical effects in the quasi one-dimensionally ordered dielectric microspheres

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1) We have established the technique for fabrication of the one-dimensionally ordered dielectric micro-spheres, whose diameter is several μm, by micromanipulator and self-organization of spheres on the glass substrate formed the groove with several μm depth by the lithography technology. Optical characteristics of a single and/or the ordered spheres using attenuation total reflection (ATR) configuration, I.e., evanescent coupling, have been able to measure with optical fiber probes which sharpened by the etching.2) We have fabricated several types of nonlinear optical microspheres coated a nonlinear thin film on a silica sphere whose diameter is about 10 μm : typically the sol-gel method for a titania glass film dispersed gold nanoparticles and the deposition method in vacuum for phthalocyanine or isoviolanthrone thin films. The microsphere coated a nonlinear film with several hundred nm thickness have shown the nonlinear optical responses in the ATR configuration with the short-pulsed laser.3) Using the finite-difference time-domain (FDTD) method, we have shown numerically that the substrate gives large effects in resonance mode excited by the evanescent coupling because the energy of the mode can escape easily to the substrate. Moreover, FDTD method including the Kerr effect has been developed. Using this, we have numerically revealed that the 1 μm diameter sphere fabricated by a semiconductor can show the optical switching characteristic in the ATR configuration.4) As a first step for the development for the FDTD including the time delay of the nonlinearity, FDTD program including the Drude dispersion of linear dielectric constant of a metal particle has been developed to simulate the linear optical response on metal nano-particle. Using this, the resonance response related to the localized polariton in metal nano-particles can be evaluated numerically.