Fujitsu Corporation

Tatsuya Tsuzuki

Norifumi Shukunami

Tomoaki Takeyama

Kyosuke Sone

Takehiro Fujita

Shigeru Ishii

Xiang Zhang

Hiroki Ooi

Kentaro Nakamura

Miki Onaka

Yuichi Suzuki

Hiroaki Tomofuji

Toshihiro Ohtani

Takuji Maeda

Tsukasa Takahashi

Masahiro Yuki

Ryosuke Goto

Yuji Tamura

Masao Nakata

Shinji Komiya

Yoshio Shimano

Hiroki Oi

Takashi Satou

Atsushi Kodama

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 transmission apparatus includes a signal power detector configured to detect signal power of a wavelength-multiplexed optical signal to be transmitted to a transmission line, a variable optical attenuator configured to attenuate the wavelength-multiplexed optical signal, and a processor configured to control an attenuation amount of the variable optical attenuator according to the signal power and whether a Raman amplifier in which pumping light is inputted to the transmission line exists.

Transmission apparatus and transmission system

A transmission device including: a signal power detection circuit that detects signal power of a wavelength-division-multiplexed optical signal to be transmitted to a transmission line into which pumping light is inputted from a Raman amplifier; a variable optical attenuator that attenuates the wavelength-division-multiplexed optical signal; and a control circuit that reduces an attenuation amount of the variable optical attenuator depending on an increase in the signal power.

Transmission device and transmission system

A transmission device includes a wavelength multiplexer that wavelength-multiplexes a plurality of optical signals having different wavelengths to generate a wavelength-multiplexed optical signal, an amplifier that outputs the wavelength-multiplexed optical signal to a transmission path, and a first processor that allocates wavelength bands to the plurality of optical signals to be wavelength-multiplexed into the wavelength-multiplexed optical signal and controls power of the wavelength-multiplexed optical signal in accordance with the wavelength bands allocated to the plurality of optical signals.

Transmission device, transmission system, 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 demultiplexer configured to demultiplex a multiplexed signal including wavelength multiplexed signals having individual wavelength bands into a wavelength multiplexed signal for each of the wavelength bands, a detector configured to detect a power value of each of the wavelength multiplexed signals for each of the wavelength bands, first compensators configured to compensate for a tilt in the wavelength multiplexed signal based on the power value for each of the wavelength bands, second compensators configured to compensate for a power of the wavelength multiplexed signal for each of the wavelength bands so as to reduce a power difference among wavelength multiplexed signals after the tilt compensation based on the power value for each of the wavelength bands, and a multiplexer configured to multiplex each of the wavelength multiplexed signals after the power compensation and output a multiplexed signal.

Optical wavelength multiplexing transmission apparatus and optical wavelength multiplexing transmission method

An optical transmission device includes: a wavelength allocation detector configured to detect wavelength allocation that indicates allocation of optical signals multiplexed in a WDM optical signal; a power adjusting unit configured to adjust powers of the optical signals multiplexed in the WDM optical signal; an optical amplifier configured to amplify the WDM optical signal output from the power adjusting unit; a power controller configured to generate a power control signal to control the power adjusting unit such that the WDM optical signal has a specified wavelength characteristic; and a correction value generator configured to generate a correction value to correct the power control signal based on the wavelength allocation. The power controller corrects the power control signal with the correction value. The power adjusting unit adjusts powers of the optical signals multiplexed in the WDM optical signal according to the corrected power control signal.

Optical transmission device that transmits wavelength division multiplexed optical signal and optical transmission system

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

A Raman amplifier includes: a pump light generator that provides a plurality of pump light beams with different wavelengths for an optical transmission medium; a gain monitor that monitors an average Raman gain in the optical transmission medium; a storage unit that stores ratio information indicating a ratio of power of the plurality of pump light beams for a specified gain characteristic with respect to an average Raman gain in the optical transmission medium; and a controller that controls the power of the plurality of pump light beams based on the average Raman gain monitored by the gain monitor and the ratio information.

Raman amplifier and gain control method

An optical transmission apparatus includes an optical amplifier configured to amplify a wavelength-division multiplexed signal light using an amplifying medium doped with a rare earth ion, a first optical transmitter configured to output a wavelength of a dual-polarization-multiplexed signal to a short wavelength side of an amplification band of the optical amplifier, a second optical transmitter configured to output a wavelength of a non polarization-multiplexed signal to a long wavelength side of the amplification band of the optical amplifier, and an optical multiplexer configured to input a wavelength-division multiplexed signal to the optical amplifier, the wavelength-division multiplexed signal comprising the non polarization-multiplexed signal and the dual-polarization-multiplexed signal.

In an optical amplification apparatus an optical amplifier amplifies an optical signal at set gain. An equalizer changes loss of the amplified optical signal according to wavelengths. A processor controls the equalizer so as to make the equalizer have a loss-wavelength characteristic corresponding to a gain tilt of the optical amplifier which occurs according to the set gain.

Optical amplifier with feedback to obtain set gain and gain tilt

There is provided an optical transmission apparatus including: a transmitter to output an optical signal to be transferred to other optical transmission apparatus; a first dummy light source to generate first dummy light having a wavelength which is not included in an optical signal received from other optical transmission apparatus; a first wavelength-multiplexer to wavelength-multiplex the optical signal received from other optical transmission apparatus, the optical signal output from the transmitter, and an optical signal with a wavelength, of the first dummy light, which is not included in the optical signal received from other optical transmission apparatus and in the optical signal output from the transmitter; and an optical amplifier to amplify an optical signal multiplexed by the first wavelength-multiplexer.

Optical transmission apparatus

A dispersion compensating apparatus includes a tunable dispersion compensator that dispersion-compensates an optical signal using a group delay property that is asymmetrical in bands outside an effective band; a set device that sets a dispersion compensation amount in the tunable dispersion compensator; and a shifter that shifts a central frequency of the effective band of the tunable dispersion compensator, based on the dispersion compensation amount set by the set device.

Dispersion compensating apparatus, dispersion compensating method, optical receiving apparatus, and optical receiving method

In an optical amplifier, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light in an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation between the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed. As a result, it becomes possible to accurately measure, with a simple configuration, the nonlinear optical properties of the optical fiber actually connected to the output port of the optical amplifier, so that the optical S/N ratio degradation due to a nonlinear optical effect can be effectively suppressed.

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Kawasaki, Japan

Tatsuya Tsuzuki