Fujitsu Corporation

Yokogawa Electric Corporation

Hitachi Cable, Inc.

Fujitsu Limited Co., Ltd.

George Ishikawa

Hiroki Ooi

Motoyoshi Sekiya

Hiroshi Nishimoto

Hiroshi Onaka

Hideyuki Miyata

Yuichi Akiyama

Kentaro Nakamura

Kazue Otsuka

Tomoo Takahara

Hiroaki Tomofuji

Takafumi Terahara

Jens Rasmussen

Susumu Kinoshita

Shigeki Watanabe

Kyosuke Sone

Masahiro Yuki

Takashi Iwabuchi

Hiroshi Nakamoto

Akihiko Isomura

Junichi Kumasako

Kazue Okazaki

Takeshi Hoshida

Yutaka Kai

Akira Miura

Terumi Chikama

Takuji Yamamoto

Hirotoshi Kodaka

Yoshinori Nishizawa

Daisuke Tanimura

Yasuyuki Suzuki

Takao Naito

Goji Nakagawa

Masato Nishihara

Setsuo Yoshida

Hiroyuki Matsuura

Naoki Kuwata

Morio Wada

Tetsuya Kiyonaga

Minoru Seino

Hideaki Arai

Takeshi Ihara

Sadao Ibukuro

Keisuke Harada

Satoshi Takasugi

Kantaro Nakamura

An optical amplification apparatus includes a front-stage semiconductor optical amplifier which amplifies an input light and a rear-stage semiconductor optical amplifier which amplifies an amplified light outputted from the front-stage semiconductor optical amplifier. The front-stage semiconductor optical amplifier exercises auto level control of an output light by exercising variable control of driving current which flows according to applied voltage higher than light emitting threshold voltage of an internal optical amplification element. The rear-stage semiconductor optical amplifier performs gate switching of a transmitted light by exercising switching control of driving current. By doing so, distortion of a waveform is controlled and optical communication quality can be improved.

Optical amplification apparatus

There is provided a repeater to relay an optical signal transmitted/received between an optical line terminal (OLT) and at least one optical network unit (ONU), the repeater including: a first port configured to receive an optical signal input from the at least one ONU; a converter circuit configured to convert an optical signal of a first transmission rate into an optical signal of a second transmission rate higher than the first transmission rate, the optical signal of the first transmission rate to be converted being included in optical signals received at the first port; and a second port configured to output the optical signal converted by the converter circuit to the OLT.

Repeater, relay method and optical transmission system

According to an aspect of an embodiment, an apparatus includes an optical branching unit for branching an input signal light in four directions, a polarization component extraction unit extracting four polarization components having mutually different polarization parameters from lights branched in four directions by the optical branching unit, and a determination unit determining input/non-input of the signal light based on the four polarization components extracted by the polarization component extraction unit.

Signal light monitoring apparatus, optical amplification apparatus and optical reception apparatus, and signal light monitoring method

There is provided a terminal apparatus including a message monitor to gather transmission request information from each of first and second terminating apparatus, a dynamic bandwidth allocation unit to allocate each transmission band in accordance with the gathered transmission request information, determine a size and an alignment position of a time slot in accordance with the allocated transmission band, determine a transmission start time of the time slot, and allocate an extinction period so as to stop a transmission of an optical signal between a time slot of the optical signal with the second transmission rate and a time slot following the time slot of the optical signal with the second transmission rate, and a MAC controller to generate a control frame for notifying each of the first and second terminating apparatus of the transmission start time and the size of the time slot.

Terminal apparatus, data transmission system and data transmission method

A relay apparatus including: a first interfacethat branches an optical signal that is input in a first direction from one side of the optical transmission line, and directs the optical signal to a first path and a second path, the first path being a processing path of an optical signal having a first transmission speed, the second path being a processing path of an optical signal having a second transmission speed that is different from the first transmission speed; a processing sectionthat executes processing on an optical signal propagating through each of the paths in accordance with a corresponding transmission speed; and a second interfacethat binds the first path and the second path of the optical signal on which the processing is executed by the processing section, by means of wavelength multiplexing and directs to the other end of the optical transmission line.

Relay apparatus, signal processing apparatus and optical communication system

An optical transmission apparatus according to the present invention comprises: a plurality of optical modulating sections serially connected to each other via optical fibers; driving sections corresponding to the optical modulating sections; delay amount varying sections that provide variable delay amounts for modulating signals to be input to the driving sections, to adjust timing between drive signals to be provided for the optical modulating sections; temperature monitoring sections that monitor the temperature of each of the optical fibers and the like; and a delay amount control section that controls the delay amount in each of the delay amount varying sections based on the monitored temperatures.

Optical transmission apparatus

An optical transmission system including an optical transmission path for transmitting WDM signals multiplexed different wavelength optical signals, the WDM signals including different bit rate optical signals or different modulation format optical signals; a repeater arranged in the optical transmission path, the repeater including a chromatic dispersion compensation unit for compensating chromatic dispersion compensation for the WDM signals; and a network management system including processes of determining a dispersion compensation ratio indicating the ratio with respect to the dispersion compensation amount at which the residual dispersion of the WDM signals are zero after transmission via the optical transmission path, on the bases of the mixture ratio of different optical signals included in the WDM signals, and variably setting the dispersion compensation amount for the in-line repeater according to the dispersion compensation ratio.

Optical transmission system and method for chromatic dispersion compensation

An optical transmission apparatus for suppressing deterioration of transmission quality due to XPM in a wavelength division multiplexing optical communication system in which an intensity modulation optical signal and a phase modulation optical signal exist in a mixed form. The apparatus has an intensity inversion signal light output section which outputs light having an intensity pattern obtained by inverting intensity changes of the intensity modulation optical signal near a wavelength of the intensity modulation optical signal in arrangement on wavelength axis of optical wavelengths that can be multiplexed as a wavelength division multiplexed signal as intensity inversion signal light, and a wavelength division multiplexed optical signal output unit which wavelength-division-multiplexes the intensity modulation optical signal, the phase modulation optical signal and light from the intensity inversion signal light output section and outputs a wavelength division multiplexed optical signal.

Optical transmission apparatus, wavelength division multiplexing optical communication system and optical transmission method

In a polarization multiplexed optical transmitting and receiving apparatus, output light from a light source section of a transmission unit is separated in a polarization separating section, and then modulated in first and second modulation sections, and the modulated lights are synthesized in a polarization synthesizing section, and transmitted to an optical transmission line. Then the polarization multiplexed light propagated through the optical transmission line is demodulated in a reception section of a reception unit, and together with this, transmission characteristic information of the reception light is transferred to the transmission unit. The transmission unit that receives the transmission characteristics information controls a delay section that adjusts a delay amount of relative phases of drive signals of the modulation sections, so that the transmission characteristics of the polarization multiplexed light are within an allowable range. As a result, pulse timing between orthogonal polarization components of the polarization multiplexed light can be flexibly changed with a simple configuration.

Polarization multiplexed optical transmitting and receiving apparatus

In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.

Chromatic dispersion compensating apparatus

A dispersion compensation method comprising the steps of: a) providing a compensation node for each predetermined number of in-line repeaters; b) carrying out dispersion compensation for the in-line repeaters with the different bit rates in common; c) carrying out wavelength demultiplexing on the optical signal for each of the different bit rates in the compensation node; and d) setting an optimum dispersion compensation amount for the optical signal of each bit rate.

Dispersion compensation method and compensation node

An interferometer for demodulating a differential M-phase shift keying signal includes a PLC type interferometer main body, a heating portion that heats the PLC type interferometer main body, and an intermediate member having a higher stiffness than that of the PLC type interferometer main body, for bonding the PLC type interferometer main body and the heating portion with each other while being sandwiched therebetween. A linear expansion coefficient difference between the PLC type interferometer main body and the intermediate member is equal to or smaller than 4.5&#xd7;10/&#xb0; C., and a thermal conductivity difference between the PLC type interferometer main body and the intermediate member is equal to or larger than 10 W/mK. A phase of an optical signal flowing through the interferometer is adjusted by using the heating portion and a second heating portion.

Interferometer for demodulating differential M-phase shift keying signal

A signal regeneration device which makes an extracted clock signal highly accurate while maintaining superior receiving sensitivity. To this end, a device of the present invention is configured to have a branch section for branching an input electrical signal which has been demodulated from a differential phase-shift modulated state; a first filter for equalizing a waveform of one of the demodulated electrical signals branched by the branch section; a clock recovery section for recovering a clock signal from the demodulated electrical signal whose waveform has been equalized by the first filter; and a data regeneration section for regenerating a data signal from a remaining one of the demodulated electrical signals branched by the branch section and from a clock signal recovered by the clock recovery section.

Signal regeneration device, optical receiver, and signal processing method

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Kawasaki, Japan

George Ishikawa