Fujitsu Corporation

Other

Noriaki Mizuguchi

Yuichi Akiyama

Kenichi Kaburagi

Takashi Toyomaki

Hiroaki Tomofuji

Tetsuo Ishizaka

Takashi Tsuda

Jens Rasmussen

Yasunori Nagakubo

Akihiko Isomura

Manabu Komiyama

Shunichi Sato

Saeko Yokoi

Toshio Ohya

Yoshikazu Terayama

Takahiro Makimoto

Takeshi Hoshida

Zhenning Tao

Kentaro Nakamura

Hideyuki Miyata

Norifumi Shukunami

Naoki Kuwata

Yoichi Oikawa

Naoki Yamamoto

Tetsuya Kiyonaga

Kiyotoshi Noheji

Makoto Murakami

Eiji Ishikawa

Tetsuji Sato

An optical transceiving apparatus includes an optical transmitting device performing polarization multiplexing on and transmitting as polarization multiplexed signal light, a first signal light of a predetermined polarization direction and a second signal light of a polarization direction different from the predetermined polarization direction; an optical receiving device receiving the signal light transmitted from the optical transmitting device through an optical transmission path; an acquiring unit acquiring information indicative of magnitude relation of intensity between the first signal light and the second signal light included in the signal light received by the optical receiving device; and a control unit controlling the magnitude relation of intensity between the first signal light and the second signal light included in the signal light output from the optical transmitting device, to be opposite to the magnitude relation indicated by the information acquired by the acquiring unit.

Optical transceiving apparatus, optical transmitting method, and optical transmitting device

An apparatus includes: a first measurer configured to measure first phase data indicating a temporal variation in a phase of a non-transferred signal that is an optical signal modulated by an optical phase modulation scheme and output from a transmitting device to an optical transmission path as the non-transferred signal; a second measurer configured to second phase data indicating a temporal variation in the phase of the optical signal transferred by the optical transmission path as a transferred signal on a side of a receiving device; a generator configured to generate differential data indicating a difference between the first phase data and the second phase data; and an extractor configured to use the differential data to extract, from the optical signal on the side of the receiving device, optical phase noise generated due to the optical transmission path.

Optical phase noise extracting device and optical phase noise extraction method

An optical transmission system includes: a reception apparatus configured to receive signal light separated from wavelength division multiplexing light; and a management apparatus configured to manage a plurality of optical transmission apparatuses that transmit the wavelength division multiplexing light, wherein the reception apparatus further comprises: an amplification section configured to amplify each power of electric signals for demodulating the signal light within a predetermined tolerance level, the electric signals being converted from mixed light of local light and the signal light input into the reception apparatus; an adjustment section configured to adjust power of the signal light input into the reception apparatus or power of the local light; and a controller configured to control the adjustment section based on an adjustment amount notified by the management apparatus, the management apparatus includes a computer.

Optical transmission system, optical reception apparatus, and signal adjustment method

The light reception unit is disposed behind each of a plurality of light sources that emits signal lights having mutually different wavelengths in a forward direction and receives a backlight emitted backward from each of the light sources. The synchronizing signal generation unit generates a synchronizing signal serving as an electric signal synchronized in phase with a drive signal for driving each of the light sources. The multiplication unit multiplies the synchronizing signal and a light reception signal serving as an electric signal obtained by receiving the backlight by the light reception unit. The light power detection unit detects power of the signal light by multiplying an integrated value of a multiplication signal obtained by multiplying the synchronizing signal and the light reception signal by the multiplication unit and a power ratio of the signal light to the backlight stored in a predetermined storage unit.

Photodetection device, photodetection method, and optical transmission device

An optical phase compensation device included in an optical receiver employing an intradyne detection method, includes a first optical phase error calculator configured to calculate a first optical phase error by averaging signal symbols of a first number of input main signals, a second optical phase error calculator configured to calculate a second optical phase error by averaging signal symbols of a second number of the main signals, wherein the second number is smaller than the first number, and a subtractor configured to subtract, from optical phase components of the main signals, one of a difference between the first optical phase error and the second optical phase error and a value obtained by multiplying the difference by a gain relative to the difference.

Optical phase compensation device, optical receiver, and optical phase compensation method

An optical signal transmitter includes: first outer modulator to generate first modulated optical signal, the first outer modulator including a pair of optical paths and a first phase shifter to give phase difference to the pair of optical paths; second outer modulator to generate second modulated optical signal, the second outer modulator including a pair of optical paths and a second phase shifter to give phase difference to the pair of optical paths; combiner to generate polarization multiplexed optical signal by combining the first and second modulated optical signals; phase controller to control the phase difference by the first phase shifter to A&#x2212;&#x394;&#x3c6; and control the phase difference by the second phase shifter to A+&#x394;&#x3c6;; and power controller to control at least one of the first and second outer modulators based on AC component of the polarization multiplexed optical signal.

Method for controlling polarization multiplexed optical signal

An optical apparatus comprising, converting units converting electrical signals into signal lights with different wavelength, polarization control units controlling polarizing states of the signal lights into polarization controlled lights respectively, an optical multiplexer multiplexing the polarization controlled lights into a multiplexed light, an optical branching unit branching the multiplexed light and outputting a branched light, a polarizing unit extracting only signal lights of the specified polarizing state from the branched light into an extracted light, and a control unit detecting intensity of the extracted light. Pilot signals are applied to modulate the electrical signals or the polarization controls. The polarization control units controls the polarizing states of the signal lights based on the pilot signal frequencies of the detection result by the control unit.

Optical apparatus using polarized orthogonal control

An OSNR monitor device includes an optical receiver including a delay interferometer which inputs an optical signal in accordance with a given bandwidth and outputs two optical signals and causes the optical signals to interfere with each other and optical detectors which outputs currents in accordance with optical powers of the optical signals output from the interferometer, an optical power monitor configured to obtain the optical powers of the optical signals received by the optical detectors included in the optical receiver, and an OSNR calculator configured to calculate an optical signal-to-noise ratio in accordance with the optical powers obtained from the optical power monitor and the reception bandwidth.

OSNR monitor device and OSNR measurement device

An optical communication device comprises a variable dispersion compensator, a photoelectric converter, and a processor. The variable dispersion compensator compensates an amount of wavelength dispersion of an optical signal received from an optical transmission line. The photoelectric converter converts the compensated optical signal into an electrical signal. The processor is operative to extract a frequency of the converted electrical signal, and to discriminate bit information of the electrical signal based on the frequency extracted using a decision phase and a decision threshold. The processor is operative to detect bit error information that is information related to an error of the discriminated bit information, and to control the amount of wavelength dispersion based on the detected bit error information.

Optical communication device and dispersion compensation method

Optical signal transmitter and method for controlling polarization multiplexed optical signal

A polarization multiplexed optical transmitter includes first and second modulation units, combiner, phase controller, and signal controller. The first and second modulation units generate first and second modulated optical signals, respectively. The first and second modulation units include first and second phase shifter to give phase difference between optical paths of corresponding Mach-Zehnder interferometer, respectively. The combiner generates polarization multiplexed optical signal from the first and second modulated optical signals. The phase controller controls the phase difference by the first phase shifter to a target value and the phase difference by the second phase shifter to a value shifted by &#x3c0; from the target value. The signal controller controls operation state of at least one of the first and second modulation units based on optical intensity waveform of the polarization multiplexed optical signal.

Polarization multiplexed optical transmitter and method for controlling polarization multiplexed optical signal

An optical receiver includes a dispersion mitigator configured to mitigate a wavelength dispersion value in an optical signal by using a set dispersion value, a phase difference signal generator configured to generate a phase difference signal by calculating the phase difference between a first clock signal included in an optical signal mitigated by the dispersion mitigator, and a second clock signal, a dispersion value adjuster configured to adjust the set dispersion value set in the mitigator, a controller configured to control fluctuations appearing in a phase difference signal generated by the phase difference signal generator when the dispersion value is adjusted by the dispersion value adjuster, and a clock generator configured to generate the second clock follow up the phase of the first clock, being based on the phase difference signal controlled by the controller.

Optical receiver and clock generation method

An optical transmitting apparatus includes a modulating unit that branches an input light and performs independent phase modulation to branched optical signals of arms, a phase adjusting unit that changes a phase difference between the optical signals of respective arms according to a control signal, a combining unit that combines modulated lights having the phase difference, an acquiring unit that acquires a positive-phase signal and a negative-phase signal from the combining unit, a subtracting unit that obtains a difference between the positive-phase signal and the negative-phase signal acquired by the acquiring unit, a detecting unit detecting a power of a differential signal from subtraction by the subtracting unit, and a control unit that changes the control signal according to signal component intensity detected by the detecting unit.

Optical transmitting apparatus

A demodulating unit demodulates a differential M-phase shift keying signal light by causing delay and interference. A phase-error detecting unit detects an error of a control phase amount of the delay and the interference caused by the demodulating unit. A control unit adjusts the control phase amount to a predetermined phase amount based on the error. A data processing unit monitors an error state of data signal that is demodulated by the demodulating unit. The control unit changes the control phase amount from the predetermined amount when the error state is in a predetermined state, and determines a reception state of the differential M-phase shift keying signal light based on an error that is detected after the control phase amount is changed.

Growing community of inventors

Kawasaki, Japan

Noriaki Mizuguchi