Fujitsu Corporation

Fujitsu Optical Components Limited

Naoki Kuwata

Tadashi Ikeuchi

Takeshi Hoshida

Kentaro Nakamura

Toru Katagiri

Tomoo Takahara

Takuji Yamamoto

Hiroki Ooi

Hiroshi Nishimoto

Yuichi Akiyama

Yutaka Kai

Toshio Ishii

Masahiro Yuki

Yoshinori Nishizawa

George Ishikawa

Toshiki Tanaka

Akira Miura

Masato Nishihara

Takatoshi Yagisawa

Tadashi Okiyama

Jens Rasmussen

Noriaki Mizuguchi

Tetsuya Kiyonaga

Koji Otsubo

Masazumi Marutani

Yasunari Arai

Tetsuji Sato

Masaru Akizawa

Katsuya Yamashita

Takashi Touge

Sukeyuki Iwata

Jens C Rasmussen

An optical receiver includes an optical amplifier that amplifies a received optical signal containing multiple wavelengths, a monitor circuit that monitors light intensities of the demultiplexed optical signal, a processor, and a memory having information representing a relationship between a total incident light intensity of the optical signal incident onto the optical amplifier and gains of the optical amplifier for the respective wavelengths. The processor repeats first calculation for determining the gains of the respective wavelengths from the memory, based on a drive current for driving the optical amplifier and an estimation value of the total incident light intensity of the optical signal, second calculation for calculating the incident light intensities of the respective wavelengths of the optical signal based on the gains and the monitored light intensities, and third calculation to calculate the total incident light intensity of the optical signal, until the total incident light intensity converges.

Optical receiver and optical transceiver module

An optical receiver includes photodetectors each provided on a corresponding channel of multiple channels and configured to detect an optical signal at the corresponding channel, a delay adjuster circuit provided before the photodetectors and configured to adjust a delay time of an optical waveform of an incoming signal on at least one channel, and a processor that controls the delay time such that a change point of a first optical waveform of a first channel is away from a data decision timing of a second optical waveform of a second channel, using information acquired from an electrical signal produced after photo-detection.

Optical receiver, optical transceiver using the same, and control method of reception of optical signals

An optical transmitter includes an optical modulator configured to modulate light from a light source; and a processor configured to generate a drive signal that is input into the optical modulator. The processor inserts a bias control signal amplitude-modulated at a low frequency, into an analog signal at fixed intervals, to generate the drive signal.

Optical transmitter and optical transmission method

An optical transmission device includes a first power monitor to monitor a first signal into which second signals with respectively different wavelengths are multiplexed so as to measure received power of the first signal; an amplifier to amplify the first signal, to generate a third signal; a driver to drive the amplifier; a demultiplexer to separate the third signal into fourth signals with the different respectively wavelengths; second power monitors each to monitor each of the fourth signals so as to measure received power of each of the fourth signals; a memory to store therein data related to gain in the amplifier, the data corresponding to each of wavelengths of the second signals, with respect to parameters which are the received power measured by the first power monitor and driving condition; and a processor to calculate power of each of the second signals.

Optical transmission device and optical transmission method

A phase shift unit provides a prescribed phase difference (&#x3c0;/2, for example) between a pair of optical signals transmitted via a pair of arms constituting a data modulation unit. A low-frequency signal fis superimposed on one of the optical signals. A signal of which phase is shifted by &#x3c0;/2 from the low-frequency signal fis superimposed on the other optical signal. A pair of the optical signals is coupled, and a part of which is converted into an electrical signal by a photodiode. 2fcomponent contained in the electrical signal is extracted. Bias voltage provided to the phase shift unit is controlled by feedback control so that the 2fcomponent becomes the minimum.

Optical transmitting apparatus, optical receiving apparatus, and optical communication system comprising them

An optical receiver includes: an optical amplifier amplifying an optical signal fed thereinto according to an operating current fed thereinto, the optical signal being a wavelength-multiplexed optical signal, a demultiplexer demultiplexing an optical signal output from the optical amplifier; and an operating-current control circuit selecting a monitoring target from a plurality of wavelength signals output from the demultiplexer and controlling the operating current of the optical amplifier so that optical power of the monitoring target is controlled to be a predetermined value.

Optical receiver

A receiving apparatus receives parallel data signals including a plurality of channels from a transmitting apparatus. The receiving apparatus includes a receiver, a detector, and a switch. The receiver receives the parallel data signals. The detector detects a first skew between channels within the receiving apparatus, and a second skew between channels prior to reception by the receiver. The switch interchanges the plurality of channels of the parallel data signals so as to reduce a total skew as a sum of the first skew and the second skew.

Receiving apparatus, transmitting-receiving apparatus, and transmission system method therefor

According to an aspect of an embodiment, a communication system includes a transmission apparatus with a coding section that generates multi-level-coded signals and transmits the multi-level-coded signals; and a deskew signal generation section that generates and transmits a deskew signal related to the multi-level-coded signals. The communication system also includes a receiving apparatus with a decoding section that decodes the multi-level-coded signals to generate decoded signals, and a deskew processing section that performs deskew processing for compensating skew among the decoded signals of the multiple channels. The deskew signal generation section generates the deskew signal that has been framed by extracting a part of the data from each of the channels of the input signals, adding framing data for enabling a receiving apparatus to recognize which channel the extracted data has been extracted from, and performing rate conversion.

Communication system

A communication apparatus in accordance with an embodiment comprises a reception unit configured to demodulate a received signal to output a first demodulated signal in dependence on a reception condition. The communication apparatus further comprises a pattern detection unit configured to detect a characteristic pattern in the first demodulated signal to output a pattern detection signal, and a pitch detection unit configured to detect a pitch of the characteristic pattern based on the pattern detection signal to output a first signal detection signal indicating that the first demodulated signal is one of an in-phase signal and a quadrature signal, or an inverted version of the one of the in-phase signal and the quadrature signal.

Communication apparatus and signal reception method

A receiving/processing unit receives signals parallelized by a parallelizing unit, and executes a frame process including frame synchronization process on the signals. A phase comparing circuit and a phase judging circuit judge whether a bit delay is present based on a phase difference between a phase of a clock signal at a clock/data recovering unit and a phase of a clock signal at the parallelizing unit. The receiving/processing unit includes a logic processing circuit that executes a bit delay process based on a result of judgment by the phase comparing circuit and the phase judging circuit.

Control method and apparatus for receiving optical signal

A data processing circuit includes: a first circuit part having a first synchronization signal; a second circuit part having a second synchronization signal, and receiving a data signal and the first synchronization signal from the first circuit part; a phase comparing part carrying out phase comparison between the second synchronization signal and the first synchronization signal in the second circuit part; and a control part controlling a phase of the first synchronization signal based on a comparison result of the phase comparing part.

Signal processing system

In a circuit suppressing jitters without a synchronizing clock signal and an increase of a circuit scale, input data is regenerated by a data regeneration circuit in a broadband, a predetermined signal pattern which generates phase deviations exceeding a predetermined value is detected from the data regenerated by the data regeneration circuit by a pattern detection circuit, a reverse phase deviation signal having reverse phase deviations of phase deviations corresponding to the predetermined signal pattern is generated by a reverse phase deviation generating circuit, and an output signal of the data regeneration circuit is canceled by a phase deviation correcting circuit with the reverse phase deviation signal.

Jitter suppression circuit

In a receiver, a skew detector detects a skew between two synchronization symbols having different wavelengths among synchronization symbols included in received signals. A skew rough adjustment calculator calculates a delay compensation amount for each received signal based on the skew and a signal delay characteristic in a transmission path. A variable delay processor deskews the received signals based on the delay compensation amount.

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Kawasaki, Japan

Naoki Kuwata