Noritsugu Yamamoto

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We study the plasmons confined at the gap between silver nanospheres and silver planar surfaces by means of angle- and space-resolved spectral cathodoluminescence. Plasmons in individual nanoparticles are excited by an electron beam, giving rise to light emission that is analyzed as a function of photon-energy, emission direction, and position of the beam(More)
A directional coupler switch structure capable of short switching length and wide bandwidth is proposed. The switching length and bandwidth have a trade-off relationship in conventional directional coupler switches. Dispersion curves that avoid this trade-off are derived, and a two-dimensional photonic crystal structure that achieves these dispersion curves(More)
We analyzed sediments and cavernicolous bivalve assemblages within cored sediments recovered from the Daidokutsu submarine limestone cave, which occurs in Pleistocene limestone on the fore-reef slope of Ie Island, off Okinawa, Japan. We found sand-sized brown grains within sediments aged 7,000–6,000 cal BP, and identified the grains as debris derived from a(More)
Monochromatic cathodoluminescence CL images of the threading dislocations in Si-doped n-GaN were observed by the TEM-CL technique. We studied dependence of the contrast and the FWHM of the dislocation image on sample thickness, accelerating voltage and temperature. The CL spectra were measured at various temperatures and were analyzed to find the property(More)
This paper presents a fabrication method and image transmission characteristics of a plastic focusing fiber which is flexible and has a nearly parabolic refractive index distribution. A new fabrication method is given, and the optimum control of index profile has been attained in order to reduce the aberration for imaging. A prototype fiber scope with TV(More)
Sophisticated measurements were made on the nanosecond time-resolved absorbance change of the purple membrane of Halobacterium halobium under cw background light irradiation (440-800 nm, 11-441 mW/cm2). A red-shifted transient species R660 (KN, Q) was found in alkaline conditions (pH > 9.3). Background light intensity effect shows that (i) R660 is(More)
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