Shigeru Tomita
Fujikura
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Publication
Featured researches published by Shigeru Tomita.
Journal of Lightwave Technology | 1990
Shigeru Tomita; Hiroyuki Tachino; Nobuyuki Kasahara
In optical-fiber networks, it is important to monitor water which seeps into splice enclosures. The fibers have residual stress at splicing points, and when water is present, this adversely affects fiber lifetime. A water sensor which has a simple structure for monitoring water at splicing points has been developed. This water sensor causes optical loss due to fiber bending when water seeps into splicing enclosures. The design method using a fiber-bending model and sensor performance are described. >
Journal of Lightwave Technology | 2010
Nobutomo Hanzawa; Kenji Kurokawa; Kyozo Tsujikawa; Takashi Matsui; Kazuhide Nakajima; Shigeru Tomita; Makoto Tsubokawa
We suppressed fiber fuse propagation in hole-assisted fiber (HAF) and photonic crystal fiber (PCF) with input powers above 14 W at 1480 and 1550 nm. This result indicates that the threshold power of fiber fuse propagation in HAF and PCF can be at least 10 times larger than that in conventional single-mode fiber (SMF) in the optical communication band. We also observed the dynamics of fiber fuse termination at a splice point between a test fiber (HAF or PCF) and a conventional fiber (SMF or dispersion-shifted fiber (DSF)). Our experimental results show that air holes in HAF and PCF play an important role in suppressing fiber fuse propagation.
Journal of Lightwave Technology | 2011
Takashi Matsui; Taiji Sakamoto; Kyozo Tsujikawa; Shigeru Tomita; Makoto Tsubokawa
We propose a new photonic crystal fiber design with a W-shaped effective index profile to achieve the largest effective area (<i>A</i><sub>eff</sub>) for telecommunication use. We realized a 220-μ m<sup>2</sup><i>A</i><sub>eff</sub> while achieving both a cable cutoff wavelength of less than 1300 nm and a bending loss compatible with ITU-T recommendations G.655 and G. 656.
Journal of Lightwave Technology | 1989
Masaaki Kawase; T. Fuchigami; M. Matsumoto; S. Nagasawa; Shigeru Tomita; S. Takashima
The loop network configuration and high-fiber-count, single-mode optical fiber ribbon cable and jointing technologies which enable a quick response to service demand and offer high reliability in the subscriber network are described. Fiber parameters were chosen for 1.3/1.55- mu m wavelength division multiplexing (WDM) transmission, and a 1000-fiber cable composed of 8-fiber ribbons was developed. A mass-fusion splicing technique and a multifiber connector were developed for the fiber ribbon. These techniques were evaluated by constructing an experimental line. It was found that they are highly suitable for midspan access, which is indispensable for the high-fiber-count loop network. >
Journal of Lightwave Technology | 1988
Shigeru Tomita; Masaaki Kawase; Hiromichi Shinohara; Tatsuya Fuchigami
Estimation formulas for wind force coefficients for self-supporting (SS) optical fiber cable are derived. Using these formulas, a procedure for evaluating the critical wind velocity that triggers galloping oscillation is provided. An SS cable with projections is designed to increase the critical wind velocity. >
Journal of optical communications | 1991
Takuya Uenoya; Shigeru Tomita; Fumihiro Ashiya
NTT started the ISDN service in 1988 and the demand for this high-speed digital service is growing rapidly. An optical fiber transmission system can provide efficiently these services. Therefore, it is necessary to construct an optical subscriber network for the future infrastructure. Single-mode optical fiber ribbon technology including jointing technology is the key to onstructing these networks. NTT has already developed high-count single-mode optical fiber technologies [1]. The construction of single-mode optical fiber cable for subscriber networks is also progressing rapidly. As this stage it is important to reduce construction and maintenance costs.
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | 1990
Shigeru Tomita; Fumihiro Ashiya; Masaaki Kawase
Electronics and Communications in Japan Part I-communications | 1991
Masaaki Kawase; Shigeru Tomita; Nobuyuki Kasahara; Takuya Uenoya
IEICE Transactions on Communications | 2017
Shigeru Tomita
Archive | 2012
Shoji Tanigawa; Katsuhiro Takenaga; Shoichiro Matsuo; Takashi Matsui; Taiji Sakamoto; Kyouzou Tsujikawa; Shigeru Tomita