Yuichiro Ikuma

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As traffic volumes carried by optical networks continue to grow by tens of percent year over year, we are rapidly approaching the capacity limit of the conventional communication band within a single-mode fiber. New measures such as elastic optical networking, spectral extension to multi-bands, and spatial expansion to additional fiber overlays or new fiber(More)
We report a multi-mode interference-based optical gate switch using a Ge(2)Sb(2)Te(5) thin film with a diameter of only 1 µm. The switching operation was demonstrated by laser pulse irradiation. This switch had a very wide operating wavelength range of 100 nm at around 1575 nm, with an average extinction ratio of 12.6 dB. Repetitive switching over 2,000(More)
Herein we report a facile method for the synthesis of N-doped crystalline mesoporous titanium dioxide (NMT) with ordered structure. Structural characterization and HR-TEM studies revealed that NMT exhibits pure anatase phase with highly crystalline ordered mesoporous structure in NMT. The N2 isotherms are of type IV with an H1 hysteresis loop and a(More)
The results of x-ray diffraction, the size of lattice parameter, and the values of oxygen diffusion coefficient in YOu-Ce02 , Gd0u-Ce02 , and Nd01.5-Ce02 systems were reviewed. In YOu-Ce02 system, the lattice parameter decreases as the concentration of YOu increases. In Gd0u-Ce02 system, the lattice parameter does not change very much. And in Nd0u-Ce02(More)
A novel waveguide loop mirror consisting of a 3-dB coupler and a loop waveguide is proposed. This is a useful component for configuring catoptric high-density integrated planar lightwave circuits (PLC). The silica loop mirrors were designed and fabricated using a locally enhanced optical confinement structure to reduce the minimum bend radius of the(More)