Takuya Komine's research while affiliated with Kyoto University and other places

We have prepared composites with anisotropic microstructure consisting of silver nanoparticles and zinc oxide pillars using an oblique angle deposition technique, and examined the optical response originating from their anisotropic morphology. The sample was obtained in three steps. First, the assembly of silver nanoparticles was prepared on a silica glass substrate by electron-beam deposition of the silver thin film and subsequent heat treatment. Next, zinc oxide was obliquely grown by using a pulsed laser deposition. Finally the zinc oxide was crystallized by the post annealing to make an array of inclined pillars grown on the top of the silver nanoparticles. The structure and morphology of the composites were elucidated by a combination of X-ray diffraction analysis and transmission electron microscopy. Optical rotation spectroscopy clarifies that the composite shows optical birefringence due to its inclined pillar morphology. The optical rotation spectrum exhibits two peaks, one being associated to the localized surface plasmon resonance of the silver nanoparticles and the other the excitons in the zinc oxide pillars. The present fabrication method is simple and can be applied to obtain anisotropic composites with relatively large dimensions.

We report on two types of optical properties enhanced by surface plasmons of metal nanoparticles. One of them is wavelength-selective enhancement of birefringence in ZnO thin films with anisotropic microstructure in which Ag nanoparticles are dispersed. The other is random laser oscillation and amplified spontaneous emission in Au core-SiO2 shell nanoparticles combined with rhodamine 6G.