Fujitsu Corporation

Kabushiki Kaisha Toshiba

Tomohiro Yamauchi

Takeshi Hoshida

Shoichiro Oda

Goji Nakagawa

Tomoyuki Kato

Takahito Tanimura

Setsuo Yoshida

Kyosuke Sone

Guoxiu Huang

Shigeki Watanabe

Takafumi Terahara

Yasuhiko Aoki

Norifumi Shukunami

Makoto Hasegawa

Tomofumi Oyama

Yoshito Kachita

Shingo Hara

Shinji Komiya

Yasunobu Kodaira

Naoki Ainaka

Rafael Puerta Ramirez

Hiroki Satou

Yu Tanaka

Optical transmission system transmits WDM signal from first node to second node via optical fiber. The optical transmission system includes: OCM that detects optical power of each wavelength channel in second node; processor that controls optical power of each wavelength channel based on detection by OCM in first node; optical circuit that adjusts optical power of each wavelength channel based on control signal from the processor in first node; and second processor that decides whether the optical powers of wavelength channels have converged to target level based on detection by OCM. When the optical powers of wavelength channels have not converged to the target level, the processor controls the optical circuit using the control signal in first cycle. When the optical powers of wavelength channels have converged to the target level, the processor controls the optical circuit using the control signal in second cycle longer than first cycle.

Optical transmission system and optical transmission device

Optical transmission system transmits WDM signal from first node to second node via optical fiber. The optical transmission system includes: first OCM that detects optical power of each wavelength channel of the WDM signal in the first node; second OCM that detects optical power of each wavelength channel of the WDM signal in the second node; first processor that calculates linear SNR of each wavelength channel based on the optical power of each wavelength channel detected by the second OCM; second processor that calculates non-linear SNR of each wavelength channel based on the optical power of each wavelength channel detected by the first OCM; third processor that calculates GSNR for each wavelength channel using the linear SNR and the non-linear SNR; and fourth processor that controls transmission power of each wavelength channel of the WDM signal based on the GSNR of each wavelength channel.

Optical transmission device, optical transmission system, and optical transmitting power control method

A wavelength conversion device includes: a first wavelength conversion circuit that wavelength-converts, by passing first multiplex light obtained by multiplexing an optical signal of a first wavelength band from each transmitter through an inside of a wavelength conversion medium by using excitation light, the first multiplex light into second multiplex light in a second wavelength band different from the first wavelength band; and a first generation circuit that generates a first control signal that controls each transmitter to shift a signal wavelength of each optical signal in the first multiplex light before wavelength conversion according to a subsequent part to which the second multiplex light after wavelength conversion in the first wavelength conversion circuit is input, and transmits the first control signal to each transmitter.

Wavelength conversion device, transmission device, and transmission system

A transmission device including a demultiplexer configured to demultiplex a multiplexed light obtained by multiplexing the plurality of wavelength division multiplexing (WDM) optical signals including different wavelength bands into the plurality of WDM optical signals, a plurality of optical amplifiers configured to amplify the plurality of WDM optical signals, respectively, a wavelength converter configured to convert a first wavelength band of the wavelength bands of at least a first WDM optical signal of the plurality of WDM optical signals amplified by the plurality of optical amplifiers into a second wavelength band of the wavelength bands of a second WDM optical signal of the plurality of WDM optical signals so that the second wavelength band does not overlap among the wavelength bands, and a multiplexer configured to multiplex the plurality of WDM optical signals which include the wavelength bands converted by the wavelength converter.

Transmission device, transmission method, and transmission system

A device includes a first excitation light source that emits first excitation light, a second excitation light source that emits second excitation light, a wavelength converter that converts signal light of a first wavelength into signal light of a second wavelength according to the first excitation light, and a measurer that measures a frequency difference between the first excitation light and the second excitation light, wherein when an abnormality of the first excitation light is detected, the second excitation light source is adjusted so that a frequency of the second excitation light is aligned with a frequency of the first excitation light before the abnormality detection, based on the frequency difference before the abnormality detection, and the wavelength converter converts the signal light of the first wavelength into the signal light of the second wavelength according to the second excitation light, after adjusting the frequency of the second excitation light.

Wavelength conversion device and excitation light switching method

A method includes multiplexing signal light of first polarization and excitation light, and multiplexing signal light of second polarization, which is perpendicular to the first polarization, and the excitation light, modulating the signal light of the first polarization before the wavelength conversion, and reducing a modulation component in signal light after wavelength conversion, modulating the signal light of the second polarization before the wavelength conversion, and reducing the modulation component in the signal light after the wavelength conversion, and multiplexing the signal light of the first polarization after the wavelength conversion and the signal light of the second polarization after the wavelength conversion.

Wavelength conversion device and method of performing wavelength conversion

An optical transmission apparatus includes a splitter configured to split a first wavelength division multiplexed optical signal arranged in a first wavelength band and a second wavelength division multiplexed optical signal arranged in a second wavelength band, respectively, from an optical signal including the first wavelength division multiplexed optical signal and the second wavelength division multiplexed optical signal, a wavelength converter configured to convert a wavelength of the split second wavelength division multiplexed optical signal to generate a third wavelength division multiplexed optical signal to be arranged in the first wavelength band, an optical monitor configured to monitor power of each wavelength channel of the third wavelength division multiplexed optical signal, and a transmitter configured to transmit a monitoring result by the optical monitor to a transmission source node of the optical signal or a relay node of the optical signal.

Optical transmission apparatus, optical transmission method, and optical transmission system

A transmitter transmitting a polarization multiplexed optical signal, includes: a light source; a generating unit configured to split a light of the light source into first and second polarized lights, optically modulate the first and second polarized lights based on an electric data signal, and multiplex the first polarized light optically-modulated and the second polarized light optically-modulated to generate the polarization multiplexed optical signal; and a coupling unit configured to couple a first reference light having a frequency different from a frequency of the light of the light source with the first polarized light and couple a second reference light having a frequency different from the frequency of the light of the light source with the second polarized light, wherein the first reference light and the second reference light have different frequencies.

Receiver and receiving method

An optical transmitter includes, an optical modulator that multilevel-modulates light outputted from a light source, and a processor that outputs a first drive voltage for driving the optical modulator according to an amplitude component when transmission data is symbol-mapped and a second drive voltage for driving the optical modulator according to a phase component when the transmission data is symbol-mapped. A phase shift of phase modulation by the second drive voltage outputted from the processor is greater than 0 and less than &#x3c0;/2.

Optical transmitter, optical transmission apparatus, and optical modulation method

A network control apparatus includes a processor. The processor calculates a first OSNR corresponding to an allowable limit BER from an OSNR yield strength curve of a transmission end in a node of a transmission end. The processor acquires a reception BER of a second node of a reception end, and calculates a second OSNR corresponding to the reception BER from the OSNR yield strength curve of the transmission end. The processor calculates a first noise intensity corresponding to the allowable limit BER from the first OSNR. The processor calculates a second noise intensity corresponding to the reception BER from the second OSNR. The processor calculates a noise intensity margin, based on the first noise intensity and the second noise intensity.

Network control apparatus and transmission quality margin calculation method

An optical transmission apparatus includes a variable attenuator configured to adjust output intensity of each wavelength signal included in a multiplexed optical signal having been input; a monitor configured to measure an output spectrum of the variable attenuator; a calculation unit configured to calculate an amount of spectral narrowing and an amount of spectral surplus, based on a measured value by the monitor, and a target value set in advance; and a control unit configured to control an amount of attenuation of the variable attenuator, based on the amount of spectral narrowing and the amount of spectral surplus.

Optical transmission apparatus, optical transmission system, and method of controlling output of optical signal

An optical receiver includes: a tunable filter configured to partially transmit a wavelength-multiplexed optical-signal including a first optical-signal having a first wavelength, a second optical-signal having a second wavelength, and a third optical-signal having a third wavelength, with a frequency-modulated signal superimposed on each of the first to third optical-signals; a photo detector configured to detect an optical-power of the wavelength-multiplexed optical-signal transmitted through the tunable filter; and a superimposed signal detector configured to detect the frequency-modulated signal superimposed on the first optical-signal, based on an amplitude-modulated signal according to a variation in the optical-power on a first filter setting where both of the first optical-signal and the second optical-signal transmit through the tunable filter, and an amplitude-modulated signal according to a variation in the optical-power on a second filter setting where both of the first optical-signal and the third optical-signal transmit through the tunable filter.

Optical receiver and superimposed signal detecting method

A transmission system includes: an acquisition section configured to acquire a free band between a target channel including a plurality of wavelength signals contiguous to one another and a channel adjacent to the target channel; and an adjustment section configured to adjust signal power of at least one of the plurality of wavelength signals in the target channel, based on a power adjustment amount for the wavelength signal, the power adjustment amount being provided for the free band acquired by the acquisition section.

Transmission system and transmission method

An optical receiver receives a wavelength multiplexed optical signal including wavelength channels. A superimposition signal is superimposed by frequency modulation on each of the wavelength channels. The optical receiver includes: an optical filter that filters the wavelength multiplexed optical signal; a filter controller that controls a wavelength of a transmission band of the optical filter; a photo detector that generates an intensity signal representing a change in the intensity of an output light of the optical filter; an signal detector that detects, according to the intensity signal, a superimposition signal superimposed on a specified wavelength channel. The filter controller controls the wavelength of the transmission band so that the amplitude of the intensity signal is larger, and then controls the wavelength of the transmission band so that the number of errors in the superimposition signal detected by the signal detector is reduced.

Optical receiver that has function to detect signal superimposed on optical signal and method for receiving optical signal

There is provided a measurement apparatus of measuring signal light quality. The measurement apparatus may include: a tunable wavelength filter configured to be input signal lights having different power levels; a measure configured to measure an optical power level of light passing through the tunable wavelength filter; and a controller configured to calculate a non-linear noise component and a spontaneous emission component of a signal light based on the measured optical power levels, the optical power levels being measured at different transmission frequencies for each of the signal lights having the different power levels in response to a control of the transmission frequency of the tunable wavelength filter.

Growing community of inventors

Kawasaki, Japan

Tomohiro Yamauchi