Nec Corporation

Hidemi Noguchi

Junichi Abe

Tomoyuki Yamase

Emmanuel Le Taillandier De Gabory

Akira Tsuji

Masaki Sato

Keiichi Matsumoto

Yasushi Amamiya

Madoka Kimura

Tetuo Tateyama

Hitoshi Takeshita

Yohei Hasegawa

Shigeyuki Yanagimachi

Wakako Yasuda

Yoshimasa Ono

Nobuhide Yoshida

Chiharu Kogiso

An optical amplifier that amplifies an incident WDM signal and includes cores having an amplification medium, the optical amplifier includes: a wavelength demultiplexer configured to demultiplex the incident WDM signal into wavelength bands and introducing the demultiplexed WDM signals into the cores separately; a wavelength multiplexer configured to multiplex amplified optical signals propagated through the cores and outputting the multiplexed signal; and an wavelength demultiplexing controller configured to monitor an amplification rate of a specific wavelength band of an amplified WDM signal or a scale associated with an amplification rate of a specific wavelength band, demultiplexing, from the incident WDM signal, an optical signal of a wavelength band having relatively-small optical amplification efficiency according to a monitoring result, and controlling demultiplexing performed by the wavelength demultiplexer in such a way as to amplify, with a relatively-large amplification rate, the optical signal of the wavelength band having relatively-small optical amplification efficiency.

Optical amplifier, optical amplifier controlling method, and optical transmission system

A generation unit () generates a plurality of transmission pulses of which the strength of an optical signal changes in a pulse-like manner. Note that the generation part () generates a plurality of transmission pulses having frequency offsets different from each other. The transmission unit () repeatedly transmits transmission pulses generated by the generation unit (). The reception part () receives reflected pulses of the respective transmission pulses reflected on a distance-measurement-target object. The detection unit () detects the frequency offsets of the reflected pulses received by the reception unit (). The distance calculation unit () calculates a distance to the distance-measurement-target object based on the receiving timings of the reflected pulses received by the reception unit () and the transmitting timings of the transmission pulses corresponding to the frequency offsets detected from the reflected pulses.

Distance-measurement apparatus and distance-measurement method

An optical signal processing circuit () includes: an FDE-MIMO equalizer () configured to generate, based on continuous subcarrier signals including a target subcarrier signal in an optical multicarrier signal to be received, the continuous subcarrier signals that have been subjected to frequency-domain MIMO equalization processing; and a TDE-MIMO equalizer () configured to generate, based on the continuous subcarrier signals that have been subjected to the frequency-domain MIMO equalization processing, the target subcarrier signal that has been subjected to time-domain MIMO equalization processing.

Optical signal processing circuit, optical reception apparatus, and optical signal processing method

There is provided a surface abnormality detection device, and a system, capable of detecting an abnormal portion having a displacement below the distance measurement accuracy when detecting the abnormal portion on the surface of a structure. A surface abnormality detection device includes a classification means for classifying an object under measurement into one or more clusters having the same structure, based on position information at a plurality of points on a surface of the object under measurement; a determination means for determining a reflection brightness normal value of the cluster based on a distribution of reflection brightness values at a plurality of points on a surface of the cluster; and an identification means for identifying an abnormal portion on the surface of the cluster based on a difference between the reflection brightness normal value and the reflection brightness value at each of the plurality of points.

Surface abnormality detection device and system

A monitoring control device () according to the present embodiment is, for example, a monitoring control device used in a monitoring system that monitors a monitoring target facility by using a distance measurement sensor (). The monitoring control device () includes: a sensing region acquisition unit () configured to acquire measurement data indicating a sensing region of the distance measurement sensor () provided in order to monitor a monitoring target facility; and a management unit () configured to identify a non-monitoring region of the monitoring target facility, based on the sensing region and position data of the distance measurement sensor ().

Monitoring control device, monitoring system, monitoring control method, and non-transitory computer-readable medium with program stored therein

Provided is a communication device that can deliver an improvement in the communication capacity of communication infrastructure with the quality of communication taken into consideration. A communication device includes an acquiring unit configured to acquire quality information of a communication line extending from a first communication device to a second communication device and including an optical communication line, an estimating unit configured to estimate the quality of communication of the second communication device and determine the required quality of communication of the second communication device based on the quality information, and a controlling unit configured to perform control on communication channels in the optical communication line so that the quality of communication satisfies the required quality of communication.

Communication device, communication controlling method, non-transitory computer-readable medium, and optical communication system

Provided are a monitoring device, a monitoring method, and an optical transmission system which are adapted for an increase in the number of cores of a multi-core optical fiber transmission path and suitable for crosstalk monitoring. The monitoring device monitors a multi-core optical fiber transmission path having a plurality of use cores and at least one or more non-use cores, and comprises: an applying means for applying, at a start point of the multi-core optical fiber transmission path, dithering to signal light propagating in the use cores; a monitoring means for monitoring the power of the non-use cores at an input side of a relay in the multi-core optical fiber transmission path; and a separating means for separating a monitoring result from the monitoring means into power components from the plurality of use cores.

Monitoring device, monitoring method, and optical transmission system

A range finding apparatus () generates a plurality of range finding signals. The range finding apparatus () generates transmission light acquired by performing at least one of quadrature modulation and polarization modulation on an optical carrier wave by using each of the generated range finding signals. The range finding apparatus () transmits the generated transmission light. The range finding apparatus () receives reflection light which is the transmission light reflected by an object to be measured. The range finding apparatus () extracts a reception signal corresponding to each of the range finding signals by demodulating the reflection light. The range finding apparatus () computes a distance to the object to be measured by using any one or more of the extracted reception signals.

Range finding apparatus and control method

A distance-measuring apparatus () generates transmission light by generating a distance measurement signal, and subjecting an optical carrier wave to quadrature modulation on the basis of the generated distance measurement signal. The distance-measuring apparatus () outputs transmission light, and receives reflected light generated by reflecting the transmission light on an object () to be measured. The distance-measuring apparatus () compares the received reflected light with reference light to compute a distance from the distance-measuring apparatus () to the object () to be measured.

Distance-measuring apparatus and control method

To suppress the deterioration of the characteristics of a MIMO equalizer as well as minimizing an increase in circuit size in spite of the occurrence of signal spectrum narrowing and asymmetric spectrum degradation, a wavelength-division multiplexing optical transmission system () according to an embodiment includes a transmitter () that generates one channel signal by wavelength-division multiplexing a plurality of subcarrier signals so as to overlap each other and transmits the channel signal, and a receiver () that separates a received channel signal into subcarrier signals, and performs equalization using an MIMO equalizer () including a FDE-MIMO equalizer () and a TDE-MIMO equalizer () on each of the separated subcarrier signals.

Wavelength-division multiplexing optical transmission system, wavelength-division multiplexing optical transmission method, and non-transitory computer readable medium

A distance measurement apparatus comprises a distance measurement optical signal generation part, a collimating part, a beam diameter change part, an emission direction control part, and a beam diameter change control part. The distance measurement optical signal generation part generates an optical signal for measuring the distance to a target. The collimating part collimates the optical signal. The beam diameter change part is able to change a beam diameter of the collimated light. The emission direction control part controls an emission destination of the collimated light with the diameter changed. The beam diameter change control part controls the changing of the beam diameter by the beam diameter change part according to the emission direction of an outgoing.

Distance measurement apparatus, distance measurement method and program

A distance measurement device () generates transmission light by modulating an optical carrier wave. The distance measurement device () transmits the generated transmission light, and receives reflected light acquired by the transmission light being reflected by a measured object (). The distance measurement device () generates a first beat signal by causing the transmission light to interfere with reference light. The distance measurement device () generates a second beat signal by causing the reflected light to interfere with the reference light. The distance measurement device () calculates a distance to the measured object (), based on a difference between the first beat signal and the second beat signal.

Distance measurement based on difference of two beat signals generated from same reference light

The receiving-side system () includes a smaller number of optical reception front ends () than the number of a plurality of wavelength-multiplexed subcarrier signals. Each of the optical reception front ends () is configured to receive two or a plurality subcarrier signals of the plurality of subcarrier signals. A frequency offset monitoring unit () monitors frequency offsets of the respective subcarrier signals received by the optical reception front end (). A light source frequency control unit () controls at least one of a light source frequency of the transmitting-side system () and a light source frequency of the receiving-side system () based on a result of the monitoring performed by the frequency offset monitoring unit ().

Optical communications system and optical frequency control method

A reception deviceis configured to include a separation meansand a plurality of optical reception means. Each optical reception meansis configured to further include an optical/electrical conversion meansand a band restoration means. The separation meansseparates a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied are multiplexed at spacings less than or equal to the baud rate on the transmission side into optical signals for the respective channels. Each optical/electrical conversion meansconverts an optical signal to an electrical signal as a reception signal. Each band restoration meansapplies processing having inverse characteristics to those of the band narrowing filter processing to the reception signal and restores the band of the reception signal.

Reception device, transmission device, optical communication system, and optical communication method

A reception deviceis configured to include a separation meansand a plurality of optical reception means. Each optical reception meansfurther includes an optical/electrical conversion means, a reception coefficient computation means, and a band restoration means. The separation meansseparates a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied as band narrowing filter processing on the transmission side, based on characteristics of a transmission line are multiplexed at spacings less than or equal to the baud rate. Each band restoration meansapplies processing having inverse characteristics to those of the band narrowing filter processing to a reception signal, based on the band narrowing parameter acquired by the reception coefficient computation meansand thereby restores the band of the reception signal.

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Tokyo, Japan

Hidemi Noguchi