Fujitsu Corporation

Hirota, Osamu

Setsuo Yoshida

Shoichiro Oda

Yutaka Kai

Kyosuke Sone

Goji Nakagawa

Yasuhiko Aoki

Masaji Noguchi

Susumu Kinoshita

Tomohiro Ueno

Keisuke Harada

Takeshi Hoshida

Hiroshi Onaka

Takahito Tanimura

Kazuyuki Tajima

Guoxiu Huang

Hideyuki Miyata

Tomohiro Yamauchi

Osamu Hirota

Taku Yoshida

Zhenning Tao

Hisao Nakashima

George Ishikawa

Toru Katagiri

Yutaka Takita

Masatake Miyabe

Yoshio Hirose

Kiichi Sugitani

Hirotomo Izumi

Shigeru Ishii

Eri Katayama

Hiroyuki Kadosono

Motohiko Eto

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.

Device and method for estimating characteristics of optical fiber transmission line

An optical network device includes a receiver that receives a polarization multiplexed optical signal and a processor. The processor separates an electric field information signal indicating the polarization multiplexed optical signal into first and second polarization components orthogonal to each other, generates third and fourth polarization components by controlling the first and second polarization components, calculates an evaluation value corresponding to a power of the third or fourth polarization component for each of a plurality of positions on a transmission line, calculates a variation in the evaluation value for a control amount for each of the plurality of positions, and decides whether a first position is a position to be detected based on a result of comparing a variation in an evaluation value for the first position with a variation in an evaluation value for a second position adjacent to the first position.

Optical network device and method for monitoring transmission line

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.

Communication device that performs encrypted communication and communication system

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.

Optical transmitter and control method for optical transmitter

A monitoring device includes a processor configured to compensate an electric field signal generated from an optical signal alternately for a chromatic dispersion and a nonlinear distortion in the optical signal in each of virtual sections of a transmission line, evaluate a quality of a compensated electric field signal, select the virtual sections sequentially, set a first compensation quantity of the chromatic dispersion according to a length of each of the virtual sections, search for a third compensation quantity of the nonlinear distortion for a selected virtual section when the quality satisfies a predetermined condition under an assumption that no nonlinear distortion is produced in other virtual sections, search for a second compensation quantity of the nonlinear distortion by setting an initial value of the second compensation quantity to the third compensation quantity, and monitor a power distribution of the optical signal based on the first and second compensation quantities.

Transmission line monitoring device and transmission line monitoring method

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.

Optical transmission apparatus and estimation method

An optical network device receives an optical signal, to which polarization information is added, from a transmitter via a transmission line. The receiver generates electric-field-information signal of the optical signal. The processor acquires, for respective polarization rotation amounts, the electric-field-information signal during a period specified by the polarization information. The processor calculates, for respective polarization rotation amounts and based on the electric-field-information signal, evaluation values corresponding to powers of the optical signal at a plurality of positions on the transmission line. The processor calculates, for respective positions, variations in the evaluation values corresponding to the polarization rotation amounts. The processor output information that indicates a first position when the variation in the evaluation values for the first position is larger than that for a second position where the second position is adjacent to the first position on a transmitter side.

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 method of controlling a transmission signal, includes transmitting a training signal including four polarization states having a given relation; and performing rotation control and transmission power level control of a polarization component of a data signal, based on a rotation control matrix for a polarization state and an inverse-operation control matrix for a power level imbalance, which are estimated from Stokes parameters related to input power level present on a Poincare sphere acquired from the training signal and Stokes parameters related to output power level present on the Poincare sphere.

Communication apparatus and method of controlling transmission signal

An optical signal-to-noise ratio measurement device includes a measurement unit and a determination unit and measures an optical signal-to-noise ratio of an optical signal including a fixed pattern in a specified cycle. The measurement unit measures an optical signal-to-noise ratio of the optical signal respectively in a plurality of time sections in a measurement period so as to generate a plurality of measured values, a length of the measurement period being the same or substantially the same as a length of the specified cycle. The determination unit selects, from the plurality of measured values generated by the measurement unit, at least one measured value other than a worst measured value in the plurality of measured values, and determines an optical signal-to-noise ratio of the optical signal based on the selected at least one measured value.

Device and method for measuring optical signal-to-noise ratio

An optical signal-to-noise ratio (OSNR) measuring device includes a processor, wherein the processor executes a process. The process includes: converting an optical signal to an electrical signal; first acquiring a signal intensity from the electrical signal; second acquiring a noise intensity of a predetermined frequency band from the electrical signal; performing a digital conversion on the noise intensity; and computing an OSNR of the optical signal based on the signal intensity and the converted noise intensity. The predetermined frequency band is a frequency band including a folding noise that occurs when the digital conversion is performed.

Optical signal-to-noise ratio measuring device and optical signal-to-noise ratio measuring method

There is provided a transmitter configured to transmit a symbol in a constellation, the symbol corresponding to data to be transmitted, the transmitter including a memory in which key information for generating pseudo random numbers are stored, and a processor coupled to the memory and configured to generate a pseudo random number every the symbol, select data patterns every data areas in which information of types of a data pattern are arranged, based on the pseudo random number, so that a distance between the data patterns to be selected is more than a predetermined value on a plane on which the data areas are continuously arranged every a horizontal axis and a vertical axis of the constellation, and determine the symbol to be transmitted, based on the selected data patterns according to a position of a data pattern corresponding to the data to be transmitted in the constellation.

Transmitter, receiver, and transmission 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

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.

Growing community of inventors

Inagi, Japan

Setsuo Yoshida