Abstract: According to an aspect of an embodiment, operations may include obtaining a first waveform profile corresponding to an optical signal received at an optical receiver via an optical link between the optical receiver and an optical transmitter. The operations may also include obtaining a second waveform profile that is an estimate of the first waveform profile. The second waveform profile may be based on one or more properties of the optical link and may be based on a complex scaling factor that accounts for rotation of the optical signal as the optical signal propagates via the optical link. In addition, the operations may include determining a power profile estimation corresponding to the optical link based on a comparison between the first waveform profile and the second waveform profile.

Abstract: In an example, a method may include obtaining anomaly characteristics associated with an anomaly in a transmission medium in an optical transmission system. The anomaly may cause a degradation in one or more signal characteristics of an optical signal traversing the transmission medium. Based on the anomaly characteristics, the method may also include adjusting a first output power of a first optical amplifier that may be disposed at an input end of the transmission medium. Alternatively, or additionally, based on the anomaly characteristics, the method may also include adjusting a second output power of a second optical amplifier that may be disposed at an output end of the transmission medium.

Abstract: A characteristics estimation device estimates characteristics of an optical fiber transmission line in an optical transmission system in which an optical signal is transmitted from first node to second node via the optical fiber transmission line. The characteristics estimation device includes a processor. The processor generates, based on electric field information indicating an electric field of the optical signal received by the second node via the optical fiber transmission line, a power profile indicating a relationship between power of the optical signal and dispersion amount corresponding to a transmission distance from the first node or the second node. The processor detects a span forming the optical fiber transmission line by using the power profile. The processor calculates, for the detected span, a dispersion coefficient of the optical fiber transmission line by dividing the dispersion amount estimated based on the power profile by a corresponding span length.

Abstract: Monitoring device monitors an optical transmission line by using electric field information signal indicating an electric field of received optical signal. The monitoring device includes a processor. The processor sequentially compensates for first chromatic dispersion among chromatic dispersion of the optical fiber transmission line, nonlinear distortion of the optical fiber transmission line, and remaining chromatic dispersion among the chromatic dispersion in the electric field information signal to generate a reference signal indicating the electric field of the optical signal in the transmitter node. The processor detects, in the electric field information signal, second distortion different from the nonlinear distortion. The processor processes the reference signal based on the second distortion to generate a second reference signal.

Abstract: A communication device includes: a counter, a pseudo-random number generator, a symbol generator, a modulator, and a controller. The counter counts symbols transmitted to a correspondent device. The pseudo-random number generator generates a pseudo-random number corresponding to a count value of the counter. The symbol generator generates a transmission symbol from a transmission signal and the pseudo-random number. The modulator generates a modulated signal from the transmission symbol. When a disruption of a communication with the correspondent device is detected, the controller selects, from among a plurality of restoring times determined in advance, a restoring time for resuming the communication, and gives the counter a count value assigned in advance to the selected restoring time. The counter resumes a counting operation from the count value given from the controller when the communication device resumes a communication with the correspondent device.

Abstract: A transmission device includes: a memory; and a processor coupled to the memory and configured to: transmit or receive an optical signal; filter an electrical electric field signal that indicates electric field information of the optical signal; calculate a transmission characteristic of filtering of the electric field signal and set the transmission characteristic in the filter on a basis of a narrowing amount of a wavelength band of the optical signal transmitted through a transmission line and a narrowing amount of the wavelength band when a state of the transmission line is changed on a basis of transmission line information regarding the transmission line of the optical signal; and set a transmission parameter of the optical signal according to quality of the electric field signal filtered by the filter.

Abstract: An optical transmitter includes: a modulator, square law detector, and a processor. The modulator generates an optical signal indicating transmission data. The square law detector detects an intensity of the optical signal using a photodetector and output first intensity data indicating the detected intensity. The processor calculates, based on the transmission data, an electric field of the optical signal generated by the modulator by using parameters pertaining to a state of the modulator. The processor calculates second intensity data indicating the intensity of the optical signal based on the calculated electric field. The processor updates the parameters so as to reduce a difference between the first intensity data and the second intensity data. The processor controls the state of the modulator based on the parameters.

Abstract: A transmission device includes: a memory; and a processor coupled to the memory and configured to: transmit or receive an optical signal; filter an electrical electric field signal that indicates electric field information of the optical signal; calculate a transmission characteristic of filtering of the electric field signal and set the transmission characteristic in the filter on a basis of a narrowing amount of a wavelength band of the optical signal transmitted through a transmission line and a narrowing amount of the wavelength band when a state of the transmission line is changed on a basis of transmission line information regarding the transmission line of the optical signal; and set a transmission parameter of the optical signal according to quality of the electric field signal filtered by the filter.

Abstract: An optical communication component includes three or more couplers, a pair of waveguides, a phase shifter, a detector, and a controller. Each of the couplers multiplexes two input optical signals and two-branch outputs the multiplexed optical signals. Each of the pair of waveguides connects between the couplers and outputs each of the optical signals two-branch output from one of the couplers to another one of the couplers. The phase shifter, included in each of the waveguides, adjusts a phase amount of each of the optical signals passing through the waveguides. The detector detects an amount of power of the optical signal that has been subjected to phase adjustment and that is two-branch output from a most downstream coupler, from among the couplers, located in the traveling direction of the optical signal. The controller controls, based on the detected amount of power, each of the phase shifters.

Abstract: An optical transmitter includes: a modulator, square law detector, and a processor. The modulator generates an optical signal indicating transmission data. The square law detector detects an intensity of the optical signal using a photodetector and output first intensity data indicating the detected intensity. The processor calculates, based on the transmission data, an electric field of the optical signal generated by the modulator by using parameters pertaining to a state of the modulator. The processor calculates second intensity data indicating the intensity of the optical signal based on the calculated electric field. The processor updates the parameters so as to reduce a difference between the first intensity data and the second intensity data. The processor controls the state of the modulator based on the parameters.

Abstract: A communication device includes: a counter, a pseudo-random number generator, a symbol generator, a modulator, and a controller. The counter counts symbols transmitted to a correspondent device. The pseudo-random number generator generates a pseudo-random number corresponding to a count value of the counter. The symbol generator generates a transmission symbol from a transmission signal and the pseudo-random number. The modulator generates a modulated signal from the transmission symbol. When a disruption of a communication with the correspondent device is detected, the controller selects, from among a plurality of restoring times determined in advance, a restoring time for resuming the communication, and gives the counter a count value assigned in advance to the selected restoring time. The counter resumes a counting operation from the count value given from the controller when the communication device resumes a communication with the correspondent device.

Abstract: A communication device includes: a counter, a pseudo-random number generator, a symbol generator, a modulator, and a controller. The counter counts symbols transmitted to a correspondent device. The pseudo-random number generator generates a pseudo-random number corresponding to a count value of the counter. The symbol generator generates a transmission symbol from a transmission signal and the pseudo-random number. The modulator generates a modulated signal from the transmission symbol. When a disruption of a communication with the correspondent device is detected, the controller selects, from among a plurality of restoring times determined in advance, a restoring time for resuming the communication, and gives the counter a count value assigned in advance to the selected restoring time. The counter resumes a counting operation from the count value given from the controller when the communication device resumes a communication with the correspondent device.

Abstract: An optical transmission device includes: a frontend circuit, a converter, an equalizer, a recovery, spectrum detector a correction information generator, and a transmitter. The frontend circuit converts an optical signal received via an optical network into an electric signal. The converter converts an output signal of the frontend circuit into a digital signal. The equalizer equalizes the digital signal or a second digital signal that is generated based on the digital signal. The recovery recovers a symbol from an output signal of the equalizer. The spectrum detector detects a reception spectrum of the optical signal based on the digital signal or the second digital signal. The correction information generator generates, according to the reception spectrum, correction information for correcting a shape of a transmission spectrum of the optical signal. The transmitter transmits the correction information to the source device.

Abstract: An optical communication component includes three or more couplers, a pair of waveguides, a phase shifter, a detector, and a controller. Each of the couplers multiplexes two input optical signals and two-branch outputs the multiplexed optical signals. Each of the pair of waveguides connects between the couplers and outputs each of the optical signals two-branch output from one of the couplers to another one of the couplers. The phase shifter, included in each of the waveguides, adjusts a phase amount of each of the optical signals passing through the waveguides. The detector detects an amount of power of the optical signal that has been subjected to phase adjustment and that is two-branch output from a most downstream coupler, from among the couplers, located in the traveling direction of the optical signal. The controller controls, based on the detected amount of power, each of the phase shifters.

Abstract: An optical transmission apparatus includes the optical transceiver configured to generate a test light for each wavelength assignable to the wavelength multiplex light to transmit the test light to the optical transmission line via the wavelength multiplexer and demultiplexer, detect a reflected light for the test light from the optical transmission line, calculate an arrival distance of the test light for the each wavelength from the reflected light for the each wavelength, and set a wavelength having a longest arrival distance among the arrival distances for the respective wavelengths, as a wavelength to be assigned to the signal light in the optical transceiver.

Abstract: An optical transmission apparatus, includes, a light source configured to output a plurality of light beams having different wavelengths to an optical fiber, a receiver configured to receive, from the optical fiber, a reflected light beam corresponding to each of the wavelengths of the plurality of light beams, and a signal processing circuit configured to estimate a polarization fluctuation portion based on a polarization state of the received reflected light beam corresponding to each of the plurality of wavelengths.

Abstract: An optical transmission apparatus, includes, a light source configured to output a plurality of light beams having different wavelengths to an optical fiber, a receiver configured to receive, from the optical fiber, a reflected light beam corresponding to each of the wavelengths of the plurality of light beams, and a signal processing circuit configured to estimate a polarization fluctuation portion based on a polarization state of the received reflected light beam corresponding to each of the plurality of wavelengths.

Abstract: An optical transmission apparatus includes the optical transceiver configured to generate a test light for each wavelength assignable to the wavelength multiplex light to transmit the test light to the optical transmission line via the wavelength multiplexer and demultiplexer, detect a reflected light for the test light from the optical transmission line, calculate an arrival distance of the test light for the each wavelength from the reflected light for the each wavelength, and set a wavelength having a longest arrival distance among the arrival distances for the respective wavelengths, as a wavelength to be assigned to the signal light in the optical transceiver.

Abstract: An optical transmission device includes: a frontend circuit, a converter, an equalizer, a recovery, spectrum detector a correction information generator, and a transmitter. The frontend circuit converts an optical signal received via an optical network into an electric signal. The converter converts an output signal of the frontend circuit into a digital signal. The equalizer equalizes the digital signal or a second digital signal that is generated based on the digital signal. The recovery recovers a symbol from an output signal of the equalizer. The spectrum detector detects a reception spectrum of the optical signal based on the digital signal or the second digital signal. The correction information generator generates, according to the reception spectrum, correction information for correcting a shape of a transmission spectrum of the optical signal. The transmitter transmits the correction information to the source device.

Abstract: A communication device includes: a counter, a pseudo-random number generator, a symbol generator, a modulator, and a controller. The counter counts symbols transmitted to a correspondent device. The pseudo-random number generator generates a pseudo-random number corresponding to a count value of the counter. The symbol generator generates a transmission symbol from a transmission signal and the pseudo-random number. The modulator generates a modulated signal from the transmission symbol. When a disruption of a communication with the correspondent device is detected, the controller selects, from among a plurality of restoring times determined in advance, a restoring time for resuming the communication, and gives the counter a count value assigned in advance to the selected restoring time. The counter resumes a counting operation from the count value given from the controller when the communication device resumes a communication with the correspondent device.