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Article type: Cover
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Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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Article type: Index
Pages
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Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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Mikio Maeda, Hiroyuki Furuta, Masao Yamamoto, Kimiyuki Oyamada
Article type: Article
Pages
1-6
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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A phase-diversity technique is a wise option to realize wideband TV program transmission systems with closely-arranged optical signals in broadcasting stations. Coherent demodulation of DPSK at 1.485Gbit/s that corresponds to the bitrate of the uncompressed HDTV signal format, has been achieved with received power of -35dBm. For this experiment, we developed a wide-band multiplier for the differential detection, which operates in baseband region with an excellent linear performance. The PSK signals can be arranged at intervals of three times of the symbol rate.
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Yasuhiro ITO, Naoyoshi NAKAMURA, Takuya KURAKAKE
Article type: Article
Pages
7-14
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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An optical sub-carrier multiplexed cable TV involves the serious drawback of clipping-induced impulsive distortion by a laser diode. Multi carrier signals have higher probability of being clipped than a single carrier signal, because of their relatively high peak to average power ratio. In order to clarify the characteristics of the clipping-induced distortion for multicarrier signals, here we consider OFDM (Orthogonal Frequency Division Multiplexing) signals. This paper compares three models for clipping : (1) restriction on absolute value of instantaneous amplitude in RF signals as a model for nonlinear amplifier ; (2) restriction on negative instantaneous amplitude in RF signals as a model for laser-diode ; and (3) restriction on root mean square value of base-band in-phase and quadrature-phase signals as a model for pre-restriction of baseband signals. In each case, characteristics of the clipping-induced impulsive distortion for OFDM signals are discussed.
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Masakatsu Tanaka, Hidekazu Tanaka, Yuji Watanabe, Tomonari Suka, Takes ...
Article type: Article
Pages
15-22
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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One of the problem in achieving SFN television broadcasting with OFDM method is the isolation between relay stations. In this paper, we verify the actual measurement data that is got from current analog frequency relay facility. As a result we come to the conclusion that these are some difficulties in obtaining coupling with current facilities. To achieve SFN, it is necessary to utilize landform or other factors.
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Akira Hirano, Hiroyuki Tsuda, Ryo Takahashi, Kazuo Hagimoto
Article type: Article
Pages
23-28
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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Increase of the bit rate of time-domain multiplexing is the important technological trend to achieve such ultra high capacity systems. Various optical processing circuits were employed in ultra high speed transmission experiments. We describe fundamental function of saturable absorber optical gate which will be a key device to establish such ultra high speed optical processing circuits using semi-conductor super-lattice structure. Several designs which will improve performance of the gate were proposed and comfirmed by experiments. We applied the gate to optical discriminator and optical de-multiplexer and reported experimental results.
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Kaoru KINJYOU, Masanori HANAWA, Mikio TAKAHARA
Article type: Article
Pages
29-34
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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This paper reports that even if gaussian pulses have been launched into an optical fiber link, soliton like pulses have automatically generated by appropriately selecting launching peak power, pulse width and chromatic dispersion. Then long distance transmission has been achieved. Moreover, To investigate under more realistic situation, then some results under the chromatic dispersion fluctuations along the fiber link have been reported. When dispersion shifted fibers with zero dispersion wavelength fluctuations of about 5nm were used to maked up the link, we confirmed that long distance transmission over 3,000km was achieved.
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Toru KATAGIRI, Masanori HANAWA, Mikio Takahara
Article type: Article
Pages
35-40
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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In WDM transmission systems, the transmission characteristics are degraded through the fiber nonlinearities effects such as cross-phase modulation (XPM), fourwave mixing (FWM) and so on. Recently, various technique to improve the transmission characteristics have been developed. In this paper, to compensate waveform distortion due to fiber nonlinearity, a novel WDM system using spread spectrum communication technique is proposed. The proposed system can suppress the XPM effects.
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Nobuaki Imai, Keizo Inagaki, Hiroshi Kawamura, Osamu Shibata, Yu Ji, Y ...
Article type: Article
Pages
41-48
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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Millimeter-wave wideband mobile communication system for application to future mobile communications has been proposed. This system is constructed by fiber-optic links between a control station and base stations and optical signal processing antennas at base stations. Optical signal processing is suitable for these systems because it is compatible with fiber-optic links and it can adaptively form multiple spot-beams by using its parallel processing capability. This paper clarifies the structure of this system, a zone structure which allows traffic variation, and an outline of optical signal processing antennas.
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Takashi Tada, Naoto Kishi, Eikichi Yamashita
Article type: Article
Pages
49-54
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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Passively mode-locked figure of eight fiber laser was composed as an all optical bistable circuit. Making use of the hysteresis characteristics of the laser, bistable operation by external optical singnals was demonstrated. The feature of this system is the controllability of the oscillation state by external optical signals only. Moreover, this system can be regarded as an optical memory because the recirculating pulse in the cavity does not change its shape under the stable mode-locked operation.
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Satoru IGUCHI, Noriyuki KAWAGUCHI, Takeshi MIYAJI, Hideyuki KOBAYASHI, ...
Article type: Article
Pages
55-60
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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An optically connected radio interferometry system being developed by National Astronomical Observatory in cooperation with NTT is described for the research objectives, the present status and the future plan. Radio telescopes forming the new type of radio interferometer are connected directly with an optical-fiber data transmission network of the maximum rate of 2.6 Gbps. It breaks sensitivity limit of a former radio interferometer in which a tape recording terminal of the maximum rate of 256 Mbps has been used. Now a first stage of development on the 256-Mbps system was finished and a full rate of 2-Gbps system has been studied by considering the most efficient use of an optical data network.
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Article type: Appendix
Pages
App1-
Published: March 18, 1997
Released on J-STAGE: June 23, 2017
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