Fujitsu Corporation

Kyosuke Sone

Yasuhiko Aoki

Goji Nakagawa

Setsuo Yoshida

Shoichiro Oda

Susumu Kinoshita

Yutaka Kai

George Ishikawa

Yoshio Hirose

Takeshi Hoshida

Toshiki Tanaka

Hideyuki Miyata

Tatsuya Tsuzuki

Tomohiro Yamauchi

Guoxiu Huang

Xiang Zhang

Zhenning Tao

Hiroshi Onaka

Takahito Tanimura

Yutaka Takita

Tomohiro Ueno

Keisuke Harada

Atsushi Kodama

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

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

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

A transmitter generates a frequency-modulated CW light so as to transmit it to a path. A receiver receives the CW light that has passed through passband filters included in the path. The receiver includes a processor. The processor measures an optical power of the received CW light every time a center frequency of the CW light is changed and transmitted by the transmitter. The processor calculates transmission characteristics of the CW light that has passed through the passband filters, on the basis of an average value of the optical power that corresponds to a center frequency of the CW light and on the basis of an amplitude component that indicates an amount of change in the optical power, the average value and the amplitude component being obtained as a result of the measurement.

Transmission device and method for measuring optical transmission characteristics

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

An optical line termination includes a detection circuit configured to detect a sleep request from a control apparatus to base stations; a determination circuit configured to determine, when the detection circuit detects the sleep request, whether processing of turning the base stations of requestees by the sleep request into a sleep state in accordance with the sleep request is approvable or not, based on a shortage bandwidth within a passive optical network in a different one of the base stations having a predetermined relationship with the requested base station; and a control circuit configured to discard the sleep request when the determination circuit determines that the processing is not approvable, or transfer the sleep request to the base station of the different requestee when the determination circuit determines that the processing is approval.

Optical line termination, communication system, and communication control method

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 communication device that receives received signal light from another communication device, the communication device includes: a receiver configured to receive signal light output from an optical filter that outputs signal light of a given wavelength included the received signal light; and a transmitter configured to transmit, to the another communication device, a control signal for controlling a wavelength of laser light for use in generation of the signal light of the given wavelength, wherein the receiver is configured to detect power of the signal light output from the optical filter; and the transmitter is configured to set, when the signal light is not successfully received in the receiver, the control signal so as to cause the another communication device to control the wavelength of the laser light, based on the power.

Communication device and wavelength adjustment method

A transmitting device coupled to a first route and a second route as communication paths on a first ring network and coupled to a third route as a communication path on a second ring network, the transmitting device includes: a first branching unit configured to branch and output signal light input from the first route to a first terminating unit and a second output unit that outputs signal light to the second route; a second branching unit configured to branch and output signal light input from the second route to a second terminating unit, a first output unit that outputs signal light to the first route, and a third output unit that outputs signal light to the third route; and a third branching unit configured to branch and output signal light input from the third route to a third terminating unit that terminates signal light and the second output unit.

Transmitting device and transmission control 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

A monitoring apparatus, that monitors a wavelength tunable optical filter for filtering an optical signal to which a frequency modulation component is added, includes: an optical filter configured to filter the optical signal output from the wavelength tunable optical filter; a detector configured to detect amplitude of the frequency modulation component included in the optical signal output from the optical filter; a generator configured to generate an output-side amplitude distribution representing a distribution of the amplitude of the frequency modulation component detected by the detector, by sweeping a transmission wavelength of the optical filter; and a monitoring unit configured to monitor arrangement of a transmission wavelength band of the wavelength tunable optical filter with respect to a spectrum of the optical signal based on the output-side amplitude distribution generated by the generator.

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Kawasaki, Japan

Kyosuke Sone