Toshio Kawazawa

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This letter describes fault localization in the optical wavelength-division-multiplexing (WDM) submarine cable networks by coherent-optical time domain reflectometry (C-OTDR). Using the bidirectional system designed for WDM signal transmission and a wavelength add/drop branching unit [add/drop branching unit (BU)] circuit, the trunk path, the branch path(More)
A low-insertion loss module with rotatable fractional wave plates was used to achieve endless polarization control at the output of a 195-km-long 2900-m deep-sea optical fiber submarine cable. The module could be compensated for state of polarization (SOP) fluctuations for frequencies up to 3 Hz. It was confirmed that a module with mechanical rotatable(More)
We carried out field trials of the developed FDD-SDMA packet cellular testbed system and demonstrated the effectiveness of the proposed forward link beamforming algorithm. Our forward link beamforming algorithm use not only unidirectional access terminal estimation but also angular spread estimation that is the proposed method and available to extract(More)
The long-term stability of the system performance is quite important to realize the practical system. In the long distance amplified lightwave system, the small fluctuations, such as polarization dependent gain and so on, cause the performance instability. In this letter, we report, for the first time, simultaneous performance measurements in the(More)
In selecting access terminals (AT) for simultaneous transmission, the effectiveness of the spatial-domain scheduler is one of the key factors that affect the performance of the space division multiple access (SDMA) based wireless packet cellular system. The forward link throughput of an SDMA based wireless packet cellular system, to the ability of our(More)
We proposed a practical wavelength demultiplexer for an optical amplifier wavelength division multiplexing (WDM) system using cascaded fiber gratings and optical circulators. Our proposed method can achieve a small excess loss and effective allocation of dispersion compensating for each channel, and introduce new channels without affecting other existing(More)
We have performed 96/spl times/11.4Gbit/s transmission over 3,800 km successfully using C-band EDFA and non-zero dispersion shifted fiber. The measured minimum Q of 96 channels is 15.1 dB, which gives sufficient margin for submarine cable systems.
The incident polarization angle and temperature dependence of the polarization and spectral response characteristics of three different types of fiber coupler are presented. The couplers are (1) the biconicalfused- twisted-taper single-mode fiber (coupler A), (2) the asymmetric-etched-fused-taper wavelength division multiplex (coupler B), and (3) the(More)
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