Fujitsu Corporation

Fujitsu Telecom Networks Limited

Tomoaki Takeyama

Keiko Sasaki

Shinichirou Muro

Shinya Inagaki

Norifumi Shukunami

Takashi Shimizu

Tatsuya Tsuzuki

Etsuko Hayashi

Kosuke Komaki

Ichiro Nakajima

Shota Mori

Yoshito Kachita

Yasushi Sugaya

Takashi Sato

Manabu Watanabe

Tomoyuki Kato

Makoto Hasegawa

Masahiro Yuki

Takehiro Fujita

Kazuo Takatsu

Junichi Sugiyama

Yoshihito Onoda

Hisashi Takamatsu

Kaoru Moriya

Shingo Hara

Shigeru Ishii

Yoshio Shimano

Shinji Komiya

Takashi Satou

Kenichi Miyama

Kazunari Tsubaki

Ryo Murakami

Masamichi Sugamoto

Atsushi Kodama

Yoshitaka Yamanaka

Yuichiro Tanaka

Ryo Karube

An optical wavelength multiplexing transmission device includes: a demultiplexer configured to demultiplex a wavelength multiplexing signal for each wavelength band from a multiplexed signal that includes wavelength multiplexing signals in a plurality of the wavelength bands; a processor configured to detect an optical power value of each wavelength multiplexing signal for each wavelength band; calculate a compensation amount used to compensate a tilt of the wavelength multiplexing signal, by using the optical power value and a predetermined calculation expression; and compensate the tilt of the wavelength multiplexing signal, based on the compensation amount; and a multiplexer configured to multiplex each wavelength multiplexing signal compensated by the processor and output the wavelength multiplexing signal to a transmission line.

Optical wavelength multiplexing transmission device and optical wavelength multiplexing transmission method

A fiber-optic communication apparatus includes an optical monitor that monitors a WDM signal in which optical signals of multiple channels are multiplexed, a processor that calculates a control value for controlling an optical power of the WDM signal, based on a power spectrum detected by the optical monitor, in a unit interval of frequency narrower than a channel bandwidth of the WDM signal, and an optical power adjusting mechanism that adjusts the optical power of the WDM signal in the unit interval of frequency based on the control value.

Fiber-optic communication apparatus, fiber-optic communication system, and optical power control method

A controller for a front-exciting Raman-amplifier that amplifies an optical signal transmitted from one end of an optical fiber to other end by inputting an excitation light to the one end, the controller includes a memory, and a processor coupled to the memory and configured to acquire communication-related information regarding communication of the optical signal in the optical fiber, when the acquired communication-related information does not indicate the communication of the optical signal, set a Raman gain of the front-exciting Raman amplifier based on a first light intensity of an amplified spontaneous scattered light of the excitation light, and when the acquired communication-related information indicates the communication of the optical signal, set the Raman gain based on a second light intensity of the optical signal output from the optical fiber.

Controller and control method for Raman amplifier

A transmission device includes: a first wavelength conversion circuit configured to convert a wavelength band of a wavelength multiplexed signal light based on a wavelength of a second excitation light by performing four-wave mixing on the second excitation light and the wavelength multiplexed signal light inputted to a second nonlinear medium; and a second wavelength conversion circuit configured to convert the wavelength band of the wavelength multiplexed signal light based on a difference between frequencies of a third excitation light and a fourth excitation light by performing four-wave mixing on the third excitation light and the fourth excitation light and the wavelength multiplexed signal light inputted to a third nonlinear medium.

Transmission device and transmission system

A transmitting apparatus includes: a first processor circuit; a second processor circuit; a modulation circuit; and a switch circuit, wherein the first processor circuit is configured to execute a generating process that includes mapping each of a plurality of bit strings to a symbol in predetermined order for each number of bits according to a multivalued degree of a multilevel modulation method, and generating a symbol information piece according to the symbol, wherein the modulation circuit is configured to modulate light in accordance with the symbol information piece based on the multilevel modulation method; wherein the second processor circuit is configured to execute a detecting process that includes detecting each of inputs of a plurality of data signals, wherein the switch circuit is configured to select the plurality of bit strings based on a detection result of inputs of the plurality of data signals.

Transmitting apparatus and transmitting method

An optical transmission apparatus includes a first transmitter configured to output an optical signal having a wavelength belonging to a first wavelength band, a switch configured to output the optical signal outputted to the first transmitter toward a first transmission line or a second transmission line, a wavelength converter configured to convert the optical signal outputted from the switch toward the first transmission line into an optical signal having a wavelength belonging to a second wavelength band other than the first wavelength band, a second transmitter configured to output an optical signal having a wavelength belonging to the first wavelength band, and a first multiplexer configured to multiplex the optical signal outputted from the first wavelength converter and the optical signal outputted from the second transmitter, and output a multiplexed optical signal to the first transmission line.

Optical transmission system, optical transmission apparatus and transmission method

A network system includes a plurality of transmission devices, each of which being provided with a wavelength selective switch including a wavelength filter, configured to transmit an optical signal for each channel; and a management device configured to manage the plurality of transmission devices. The wavelength selective switch configured to enable band setting that widens a transmission band of an optical signal of a predetermined channel to the wavelength filter of an adjacent channel. The management device is further configured to calculate an OSNR of the optical signal based on power loss, calculate a bandwidth of the optical signal according to narrowing due to the wavelength filter, determine whether or not the OSNR and the bandwidth respectively satisfies a condition of transmission quality of the optical signal, and decide whether or not to cause the wavelength selective switch to perform the band setting based on a result of the determination.

Network system, management device, and management method

A transmission apparatus includes a first multiplexer configured to multiplex light of wavelengths of a first wavelength band to output first wavelength multiplex light, a first wavelength converter configured to convert the first wavelength multiplex light into wavelengths of a second wavelength band which is different from the first wavelength band, by using first excitation light, a second multiplexer configured to multiplex light of wavelengths of the first wavelength band which are different from the wavelengths of the first wavelength multiplex light to output second wavelength multiplex light, a second wavelength converter configured to convert the second wavelength multiplex light into wavelengths of the second wavelength band, by using second excitation light, a third multiplexer configured to multiplex the first wavelength multiplex light converted into the wavelengths of the second wavelength band, and the second wavelength multiplex light converted into the wavelengths of the second wavelength band.

Transmission apparatus and transmission method

A wavelength conversion apparatus includes a multiplexer-demultiplexer configured to include a first port, a second port, and a third port, a looped non-linear optical medium including one end that is optically connected to the second port of the multiplexer-demultiplexer, another end that is optically connected to the third port of the multiplexer-demultiplexer, and a main axis that rotates by 90 degrees between the second port and the third port, a first filter configured to be inserted into the non-linear optical medium, and remove stimulated Brillouin backscattered light that is bidirectionally generated in the non-linear optical medium, and a second filter configured to take out, from output light that is multiplexed in the multiplexer-demultiplexer after propagating through the non-linear optical medium and is outputted from the first port, conversion light having a third frequency different from the frequencies of a signal light and an excitation light.

Wavelength conversion apparatus, optical parametric amplifier, transmission apparatus, and optical transmission system

A wavelength conversion device includes a light source configured to output an excitation light beam, a modulator configured to phase-modulate the excitation light beam, a polarization adjustor configured to adjust a polarization angle of the excitation light beam to 45 degrees or 135 degrees with respect to a polarization angle of a signal light beam, and a nonlinear medium configured to generate four-wave mixing of the excitation light beam whose polarization angle is adjusted and the signal light beam to generate an idler light beam having a frequency corresponding to a difference between frequencies of the signal light beam and the excitation light beam from the signal light beam.

Wavelength conversion device, transmission device, and transmission system

An optical transfer method of an optical transfer system including a transmitter, a first wavelength converter configured to use first excitation light to perform wavelength-conversion of first signal light which is the transmission light into second signal light in a different wavelength band, a second wavelength converter configured to use second excitation light to perform wavelength-conversion of the second signal light into third signal light in a different wavelength band, and a receiver configured to receive the third signal light, the method includes acquiring a wavelength of the transmission light, a wavelength of the first excitation light, and a wavelength of the second excitation light; and deciding local emission light of the receiver based on a wavelength of reception light of the receiver obtained from the wavelength of the transmission light, the wavelength of the first excitation light, and the wavelength of the second excitation light.

Optical transfer system, control device, optical transfer method, and transfer device

A converter includes a combiner configured to polarization-combine a first pump light and a second pump light, a nonlinear medium configured to wavelength-convert first signal light into second signal light to output the second signal light after wavelength conversion from a second port, and to wavelength-convert the second signal light into first signal light to output the first signal light after wavelength conversion from the first port, a first circulator configured to input the first signal light from the first port into the nonlinear medium, and output the first signal light after wavelength conversion in the nonlinear medium from the first port, and a second circulator configured to input the second signal light from the second port into the nonlinear medium, and output the second signal light after wavelength conversion in the nonlinear medium from the second port.

Wavelength converter, wavelength conversion method, and transmission device

There is provided an optical transmission control device includes a memory, and a processor coupled to the memory and the processor configured to aggregate information of candidacy sections having a possibility that communication is discontinued among wavelength-multiplexed transmission sections, classify, based on the aggregated information, optical paths set between optical transmission devices into a first optical path on which, when communication in the candidacy sections is discontinued, an optical signal is not transmitted, and a second optical path on which, when the communication in the candidacy sections is discontinued, an optical signal is transmitted, and determine a wavelength allocation in a first wavelength group of the first optical path and a second wavelength group of the second optical path so that a difference in gain wavelength characteristics of the first optical path and the second optical path is equal to or less than a predetermined level.

Optical transmission control device and optical signal wavelength determination method

An optical amplifier includes: an amplification section includes a plurality of routes; a determination section that selects a passage route, through which the multi-wavelength optical signal passes, among the plurality of routes; an input-side detector that detects input power of the multi-wavelength optical signal input to the amplification section; a variable optical attenuator that attenuates the multi-wavelength optical signal that is amplified through passing through the passage route determined by the determination section; an output-side detector that detects output power of the multi-wavelength optical signal attenuated by the variable optical attenuator; a controller that controls the amplification section based on the input power detected by the input-side detector and the output power detected by the output-side detector such that a gain of the amplification section is steady; and an adjuster that adjusts an attenuation of the variable optical attenuator in accordance with the input power detected by the input-side detector.

Optical amplifier, optical transmission apparatus, and optical repeating apparatus

An optical amplifier includes an optical amplifying unit, a splitting unit, and a loss adjusting unit. The optical amplifying unit provides gain to wavelength multiplexed light received from a transmission line, to amplify light intensity. The splitting unit splits the amplified wavelength multiplexed light. The loss adjusting unit adjusts loss provided to each wavelength of a first portion of the split wavelength multiplexed light based on the gain.

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Yokohama, Japan

Tomoaki Takeyama