Takuji Nagashima

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It was experimentally and theoretically confirmed for the first time that inter-core crosstalk can be varied more than 20dB depending on bending radius. Simulation results based on coupled-mode equation with equivalent index model are in good agreement with measurement results.
Propagation characteristics of seven-core fiber were investigated for multiplexed signals of spatial-division and wavelength-division. Effect of chromatic dispersion and inter-core crosstalk were evaluated for 5-km fiber by using 10-Gbit/s channels.
We demonstrate cladding-pumped six-core Erbium-doped fiber amplifiers (EDFAs) using two different pump coupling schemes: edge-coupled and side-coupled pumping, where a single multimode laser diode can be applied to pump all cores. Using two in-line cladding-pumped EDFAs at the input and output of a 31-km coupled-six-core fiber, we realized 465-km(More)
Data traffic is growing exponentially due to the emergence of various network services such as video streaming and smartphones. The transmission capacity of the optical fiber has also been increasing exponentially due to the rollouts of technologies such as wavelength-division multiplexing (WDM)*1 and the multi-level modulation*2; however, the capacity is(More)
Design and fabrication results of a 6-mode 19-core fiber with the highest relative core multiplicity factor of 30 for weakly-coupled mode-multiplexed uncoupled-core-multiplexed transmission are detailed. Technical challenges for long-haul transmission are also discussed.
We demonstrate fine tuning of the resonant wavelength of a nanocavity in a two-dimensional silicon-based photonic crystal slab structure by subnanometer control of the airhole diameter and slab thickness. Theoretical investigation shows that the resonant wavelength depends linearly on the latter two parameters. To experimentally demonstrate the fine tuning(More)
This paper describes a six-mode 19-core fiber with 114 spatial modes, which was designed and fabricated for weakly-coupled mode-division-multiplexed (MDM) transmission over uncoupled cores. The 19 identical graded-index cores were packed on a hexagonal lattice with a 62-μm pitch in a ∼318-μm-diameter cladding. The cladding diameter is(More)
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