Abstract: An apparatus includes a light source that causes continuous oscillation light to enter one terminal of an optical transmission line, wherein the continuous oscillation light is to propagate a light variation of a first physical amount generated on the optical transmission line to another terminal of the optical transmission line; a photodetector that detects, on the one terminal, light turned back from a light modulation converter provided on the another terminal, wherein the light modulation converter obtains the turned-back light by converting the light variation of the first physical amount into a light variation of a second physical amount; and a processor that calculates a light-variation location generated on the optical transmission line by comparing time variations in the light variation of the first physical amount and the light variation of the second physical amount in the light detected by the photodetector.

Abstract: 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 ?/2.

Abstract: There is provided a transmission apparatus including a transmitter configured to modulate a signal to a first signal having a first wavelength and a signal to a second signal having a second wavelength, and transmit the first signal and the second signal to a transmission line so that the second signal is varied in accordance with variation in an amount of cross phase modulation of the first signal passing through each position on the transmission line, and a signal processor configured to include at least one of a logic device and a processor, and configured to add an amount of chromatic dispersion at which a remaining amount of chromatic dispersion of the first wavelength at a certain position on the transmission line is equal to zero to the first wavelength in the transmission of the first signal and the second signal.

Abstract: An apparatus includes a light source that causes continuous oscillation light to enter one terminal of an optical transmission line, wherein the continuous oscillation light is to propagate a light variation of a first physical amount generated on the optical transmission line to another terminal of the optical transmission line; a photodetector that detects, on the one terminal, light turned back from a light modulation converter provided on the another terminal, wherein the light modulation converter obtains the turned-back light by converting the light variation of the first physical amount into a light variation of a second physical amount; and a processor that calculates a light-variation location generated on the optical transmission line by comparing time variations in the light variation of the first physical amount and the light variation of the second physical amount in the light detected by the photodetector.

Abstract: There is provided a monitor device for monitoring a transmission line including a memory, and a processor coupled to the memory and configured to compensate for a portion of chromatic dispersion on electric signals indicating an electric field component of an optical signal, compensate for deterioration due to a nonlinear optical effect on the electric signals on which the portion of chromatic dispersion is compensated, compensate for a remaining chromatic dispersion except for the portion of chromatic dispersion on the electric signals on which the deterioration due to the nonlinear optical effect is compensated, evaluate quality of the electric signals on which remaining chromatic dispersion except for the portion of chromatic dispersion are compensated, and acquire a first compensation amount of the portion of chromatic dispersion and a second compensation amount of the deterioration due to the nonlinear optical effect, when the evaluated quality satisfies a predetermined condition.

Abstract: A signal processing device processes an electric field information signal indicating a polarization multiplexed optical signal in which different modulation formats are used. A first optical signal transmitted in a first polarization component and a second optical signal transmitted in a second polarization component are multiplexed in the polarization multiplexed optical signal. The signal processing device includes a generator and a compensation circuit. The generator selects the first polarization component or the second polarization component based on modulation formats of the first and second optical signals, and generates a compensation value for compensating for an electric field information signal of a selected polarization component based on the electric field information signal of the selected polarization component. The compensation circuit compensates for electric field information signals of the first and second polarization components using the compensation value generated by the generator.

Abstract: An optical transmitter includes: a light source configured to generate CW light; a drive signal generator configured to generate a drive signal; an optical modulator configured to modulate the CW light with the drive signal so as to generate a first optical signal; a combiner configured to combine the first optical signal and a second optical signal generated by using another light source; and a detector configured to detect a frequency difference between a frequency of the CW light and a center frequency of the second optical signal. The drive signal generator includes: a mapper configured to generate an electric field information signal based on input data; and a frequency controller configured to modify the electric field information signal based on the frequency difference such that the frequency of the CW light matches the center frequency of the second optical signal to generate the drive signal.

Abstract: There is provided an optical transmission device including: a generator configured to convert an electric signal into a plurality of parallel signals, modulate the plurality of parallel signals, shift center frequencies of spectra of the plurality of modulated parallel signals into different frequencies, so as to generate signals accommodated in a plurality of sub-channels each having different center frequencies, and generate a multiplexed signal by multiplexing the signals accommodated in the plurality of sub-channels; a transmitter configured to optical-modulate the multiplexed signal and transmit the optical-modulated signal to an optical reception device; and a controller configured to control a frequency spacing between adjacent sub-channels of the plurality of sub-channels, based on a monitoring result of reception characteristics of the signals accommodated in the plurality of sub-channels within the multiplexed signal in the optical reception device.

Abstract: A data collecting device includes a receiver configured to receive an optical signal; an optical-to-electrical converter configured to convert the optical signal received by the receiver into an electrical signal; an analog-to-digital converter configured to convert the electrical signal into a digital signal; a data reducing circuit configured to reduce the digital signal output from the analog-to-digital converter; and a transmitter configured to transmit, to a managing device that manages the data collecting device, a signal obtained by reducing the digital signal by the data reducing circuit.

Abstract: An optical transmitter includes: a mapper configured to generate an electric-field-information signal from transmission data; a training-signal-generation section configured to generate a training signal; a training-signal-insertion section configured to insert the training signal into the electric-field-information signal; a driver configured to generate a drive signal from the electric-field-information signal into which the training signal is inserted; a modulator configured to generate an optical-modulation signal based on the drive signal; an optical receiver configured to generate an intensity signal indicating intensity of the optical-modulation signal; a training-signal-extraction section configured to extract an intensity-training signal corresponding to the training signal, from the intensity signal; a coder configured to generate a coded-training signal by coding the intensity-training signal extracted by the training-signal-extraction section using the training signal generated by the training-sig

Abstract: An optical receiver includes a dividing unit, a control unit, and a compensating unit. The dividing unit divides an optical transmission signal into a plurality of frequency components by a set number of divisions and a set division bandwidth. The control unit controls the number of divisions and the division bandwidth on the basis of transmission path information about an optical transmission line through which the optical transmission signal is transmitted and signal information about the optical transmission signal. The compensating unit compensates optical nonlinear distortion of each of the frequency components divided by the dividing unit.

Abstract: Input light includes a multicarrier signal and first CW light of a first optical frequency. A transmitter generates a modulated optical signal based on an inverted signal of a dropped signal. A light source generates second CW light of a second optical frequency. A delay element adjusts a phase difference between the modulated optical signal and the second CW light. The multicarrier signal, the first CW light, the modulated optical signal and the second CW light are input to nonlinear optical medium. A detector detects beat frequency component between the modulated optical signal and the second CW light. A controller controls the delay element so as to increase the beat frequency component. A difference between the first optical frequency and an optical frequency of the dropped optical signal is substantially the same as a difference between the second optical frequency and an optical frequency of the modulated optical signal.

Abstract: An apparatus which transmits data and control information which indicates at least one of a demodulation method and a decoding method of the data using an optical signal, includes: a modulator configured to perform modulation in which a rate of change of a polarization state of light is changed according to the control information, and modulation in which a characteristic of light which is different from the rate of change of the polarization state is changed in accordance with the data; and an emitting section configured to emit light, on which modulation is performed using the modulator, to another communication apparatus via a free space.

Abstract: There is provided an optical transmission device including: a generator configured to convert an electric signal into a plurality of parallel signals, modulate the plurality of parallel signals, shift center frequencies of spectra of the plurality of modulated parallel signals into different frequencies, so as to generate signals accommodated in a plurality of sub-channels each having different center frequencies, and generate a multiplexed signal by multiplexing the signals accommodated in the plurality of sub-channels; a transmitter configured to optical-modulate the multiplexed signal and transmit the optical-modulated signal to an optical reception device; and a controller configured to control a frequency spacing between adjacent sub-channels of the plurality of sub-channels, based on a monitoring result of reception characteristics of the signals accommodated in the plurality of sub-channels within the multiplexed signal in the optical reception device.

Abstract: An optical transmitter includes a circuit that controls a first frequency component and a second frequency component that are contained in an optical signal to be transmitted to be in different polarization states from each other.

Abstract: Input light includes a multicarrier signal and first CW light of a first optical frequency. A transmitter generates a modulated optical signal based on an inverted signal of a dropped signal. A light source generates second CW light of a second optical frequency. A delay element adjusts a phase difference between the modulated optical signal and the second CW light. The multicarrier signal, the first CW light, the modulated optical signal and the second CW light are input to nonlinear optical medium. A detector detects beat frequency component between the modulated optical signal and the second CW light. A controller controls the delay element so as to increase the beat frequency component. A difference between the first optical frequency and an optical frequency of the dropped optical signal is substantially the same as a difference between the second optical frequency and an optical frequency of the modulated optical signal.

Abstract: An optical transmission system includes an optical transmitter and an optical receiver. The optical transmitter includes: a first digital signal processor configured to generate an electric-field information signal corresponding to a transmission signal; and a transmitter front-end configured to generate an optical signal from the electric-field information signal. The optical receiver includes: a receiver front-end configured to generate an electric signal corresponding to the optical signal; and a second digital signal processor configured to detect polarization dependent effects on the optical signal based on the electric signal. The first digital signal processor corrects the electric-field information signal based on the polarization dependent effects detected by the second digital signal processor in the optical receiver.

Abstract: A digital coherent receiving apparatus includes a first oscillator for outputting a local light signal of a fixed frequency, a hybrid unit mixing the local light signal with a light signal received by a receiver, a second oscillator for outputting a sampling signal of a sampling frequency, a converter for converting the mixed light signal into digital signal synchronizing with the sampling signal, a waveform adjuster for adjusting a waveform distortion of the converted digital signal, a phase adjustor for adjusting a phase of the digital signal adjusted by the waveform adjustor, a demodulator for demodulating the digital signal adjusted by the phase adjuster, and a phase detector for detecting a phase of the digital signal adjusted by the phase adjuster, and a control signal output unit for outputting a frequency control signal on the basis of the detected phase signal to the second oscillator.

Abstract: A non-linear distortion compensator includes: a non-linear distortion calculator that calculates non-linear distortion occurred in a received optical signal based on signal information after recovery of a carrier wave in a carrier wave phase recovery which recovers a phase of the carrier wave of the received optical signal; and a non-linear compensator that compensates the non-linear distortion of the received optical signal based on the non-linear distortion obtained by the non-linear distortion calculator.

Abstract: An optical transmitter includes: an optical modulator configured to generate an optical signal from a plurality of transmission signals; a crosstalk monitor configured to monitor crosstalk between the plurality of transmission signals by using the optical signal; and a crosstalk canceller configured to correct the plurality of transmission signals based on a result of monitoring by the crosstalk monitor.