Fujitsu Corporation

Goji Nakagawa

Kyosuke Sone

Yasuhiko Aoki

Setsuo Yoshida

Kazuhiro Tanaka

Shoichiro Oda

Kazunori Miura

Takeshi Hoshida

Seimi Sasaki

Yutaka Kai

Tomoyuki Kato

Hiroyuki Nobuhara

Yoshio Hirose

Tomohiro Yamauchi

Susumu Kinoshita

Hideyuki Miyata

Haruhiko Tabuchi

Ryoichi Ochiai

Takafumi Terahara

Naoki Yamamoto

Tomohiro Ueno

Masaaki Norimatsu

Hideo Sumiyoshi

Yousuke Yamazaki

Youske Yamazaki

Tsuyoshi Yamamoto

Hiroshi Onaka

George Ishikawa

Toru Katagiri

Yoshihiro Yoneda

Yutaka Takita

Masatake Miyabe

Koji Terada

Tadao Inoue

Masaaki Kawai

Masaji Noguchi

Guoxiu Huang

Shigeru Ishii

Keisuke Harada

Hiroki Oi

Akira Fukushima

Koji Suzuki

Noboru Terai

Taizo Nosaka

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

An optical transmission system includes a first optical node, a second optical node, and an optical fiber provided between the first optical node and the second optical node. The optical transmission system further includes: a signal generator provided in the first optical node and configured to generate an optical signal including a plurality of wavelength channels and an empty channel; an optical transmission circuit provided in the first optical node and configured to output the optical signal to the optical fiber; an optical channel monitor provided in the second optical node and configured to measure reception power of each channel in the optical signal received through the optical fiber; and a processor configured to determine a type of the optical fiber based on the reception power of the empty channel, the reception power being measured by the optical channel monitor.

Optical transmission system and fiber type determination method

A wavelength converter that converts signal light and pump light into a light containing a new wavelength component using a nonlinear optical fiber, has a PBS for splitting incident light into a first polarized wave and a second polarized wave, a first polarization controller provided between the PBS and a first end of the nonlinear optical fiber, and a second polarization controller provided between the PBS and a second end of the nonlinear optical fiber, wherein in an optical loop connecting the PBS, the first polarization controller, the nonlinear optical fiber and the second polarization controller, the first polarized wave and a first component of the pump light travel through the nonlinear optical fiber in a first direction, and the second polarized wave and a second component of the pump light travel through the nonlinear optical fiber in a second direction opposite to the first direction.

Wavelength converter and fiber optic transmission system

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

A wavelength converter includes an excitation light source outputting excitation light, a beam splitter receiving an input of the excitation light and an input of the optical signal and to divide both the inputted excitation light and the inputted optical signal into a first polarization component and a second polarization component, a non-linear optical fiber as a non-polarization-maintaining fiber, an accommodation section securing and accommodating the non-linear optical fiber, a first collimator lens disposed between the beam splitter and a first end of the non-linear optical fiber, and a second collimator lens disposed between the beam splitter and a second end of the non-linear optical fiber, wherein the optical signal is inputted to the beam splitter from a direction different from the input of the excitation light.

Wavelength converter and transmission apparatus

A wavelength converter includes a first phase modulator configured to perform phase modulation on pump light in accordance with a first phase modulation signal, a second phase modulator configured to perform phase modulation on signal light in accordance with a second phase modulation signal, a wavelength converter configured to multiplex the signal light having undergone the phase modulation with the pump light having undergone the phase modulation, the wavelength converter configured to perform wavelength conversion on the signal light in accordance with the pump light, a detector configured to detect a modulation component from the signal light having undergone the phase modulation and the pump light having undergone the phase modulation, and a generator configured to generate the first phase modulation signal and the second phase modulation signal so as to minimize the detected modulation component.

Wavelength converter apparatus and method of performing wavelength conversion

An optical transmission apparatus includes a wavelength variable filter whose transmission light wavelength is variable; a receiver that receives light, the light being sent from another optical transmission apparatus and passing through the wavelength variable filter; a transmitter that sends to the another optical transmission apparatus, a utilization permission request for a second wavelength corresponding to a first wavelength of the light received by the receiver, the transmitter sending the utilization permission request as light of the second wavelength and in a form of a tone signal of a predetermined frequency; and a controller that, when receiving from the another optical transmission apparatus, a utilization permission notification of the second wavelength for a sender of the utilization permission request, configures a wavelength of a main signal to the second wavelength, the main signal being sent from the transmitter to the another optical transmission apparatus.

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

A transmission device includes an interface configured to acquire, from a base band unit having a communication destination that is one of remote radio heads, communication destination information relating to the remote radio head of the communication destination, a receiver configured to receive signals of given wavelength from optical termination devices, and a transmitter configured to transmit a first signal that includes wavelength information indicative of the given wavelength and the communication destination information to optical termination devices, wherein, when the receiver receives, from an optical termination device of the remote radio head of the communication destination from among optical termination devices, a second signal of the given wavelength according to the first signal, the receiver sets, between the receiver and the optical termination device, a relay path that relays communication between the base band unit and the remote radio head of the communication destination.

Transmission device, optical termination device, transmission system, and transmission method

An optical terminal device includes: a relay processing circuitry relaying communication between first base stations, respectively connected to optical terminating devices at branch destinations of a transmission path, and a control device controlling the first base stations in accordance with information acquired from a second base station covering a cell overlapping cells of the first base stations; a detecting circuitry detecting a sleep control instruction, issued for one of the first base stations from the control device, from the communication being relayed by the relay processing circuitry; and a control circuitry performing control, via the transmission path, to cause the optical terminating device connected to the one of the first base stations to shift to an operating state or a sleep state, which consumes less power than the operating state, in response to detection of the sleep control instruction, the optical terminating device being one of the optical terminating devices.

Optical terminal device, optical terminating device, and communication control method

A transmission apparatus including: a branch circuit that branches a signal including first data and second data superimposed on the first data into two signals; a limiting amplifier that amplifies one signal in the two signals; a linear amplifier that amplifies another signal in the two signals; a first detector that detects the first data from the amplified one signal; and a second detector that detects the second data from the amplified another signal and the amplified one signal.

Transmission apparatus, transmission system and data detection method

An optical transmitting apparatus includes a variable optical attenuator of a magneto-optical effect type disposed by spatial coupling between a light source and an optical fiber, the variable optical attenuator configured to attenuate light output from the light source and coupled to the optical fiber, according to an input driving voltage; a generator configured to generate the driving voltage of the variable optical attenuator based on information to be superimposed on the light by the variable optical attenuator, the generator inputting the generated driving voltage into the variable optical attenuator; and a controller configured to control a bias of the driving voltage generated by the generator, the controller controlling an amplitude of the driving voltage generated by the generator, based on data according to characteristics between the driving voltage and an attenuation amount of the light by the variable optical attenuator.

Optical transmitting apparatus and optical level control method

An optical communication system includes an optical transmitter, a plurality of optical receivers, and a splitter that splits light transmitted by the optical transmitter to the plurality of optical receivers. The optical transmitter includes a variable-wavelength light source capable of transmitting light of a first wavelength and light of a third wavelength between the first wavelength and a second wavelength. A first optical receiver of the plurality of optical receivers includes a first optical filter having a first transmission band including the first and third wavelengths, and a first receiving unit that receives light having passed through the first optical filter. A second optical receiver of the plurality of optical receivers includes a second optical filter having a second transmission band including the second and third wavelengths, and a second receiving unit that receives light having passed through the second optical filter.

Optical communication system, transmission station, and method of optical communication

A processor of an optical transport apparatus is configured to transport an optical multiplexed signal between the optical transport apparatus and a counterpart apparatus by using a plurality of communication units; transmit an arbitrary optical wavelength from the optical multiplexed signal passing through ports by using a wavelength selective switch that has the ports respectively connected to the communication units; control a radio unit in the counterpart apparatus so as to change a frequency of the radio signal in the specified optical wavelength; and change a transmission band of the port through which the optical wavelength passes, according to a change of the frequency of the radio signal. The processor is configured to control an optical transmission unit of the counterpart apparatus so as to change a center wavelength of an optical wavelength passing through the port to a center wavelength of the changed transmission band of the port.

Optical transport apparatus and optical-wavelength defragmenting method

There is provided an apparatus configured to estimate optical transmission performance in a transmission path of an optical signal, the apparatus including a memory, and a processor coupled to the memory and the processor configured to acquire a first index related to a first transmission performance of an optical signal transmitted through a span group between a first node and an n-th node and a second index related to a second transmission performance of an optical signal transmitted through a span or a span group between the first node and an m-th node, wherein n is an integer of 3 or more, and m is the integer satisfying m&#x3c;n, and estimate a third index related to a third transmission performance of an optical signal to be transmitted through a span between the m-th node and the n-th node, based on the first index and the second index.

Apparatus and method for estimating optical transmission performance

An optical receiver receives signal light obtained by superimposing a second signal to a first signal according to a predetermined superimposition pattern. In the optical receiver, a tunable optical filter allows a part of a spectrum of the received light to pass, and a photodetector converts the transmission light into an electrical signal. A filter controller controls a center transmittance frequency of the tunable optical filter in response to a superimposed period and a non-superimposed period of the second signal identified based on the electrical signal. A superimposed signal detector detects the second signal based on the electrical signal obtained in response to the control of the tunable optical filter during the superimposed period. An optical signal-to-noise ratio (OSNR) calculator calculates an OSNR of the signal light based on the electrical signal obtained in response to the control of the tunable optical filter during the non-superimposed period.

Optical communication system, optical receiver and optical transmitter

Growing community of inventors

Sagamihara, Japan

Goji Nakagawa