Fujitsu Corporation

Ntt Electronics Corporation

Hiroshi Ogiwara

Tomohiro Kaneoka

Yuichi Akiyama

Kenji Ohta

Kenji Ota

Shigeru Ono

Kouichi Ogihara

Tsutomu Aiba

A signal processing device includes an electric connector to which a transmitting and receiving device, which transmits and receives a signal, is connectable; a first processor configured to compensate for, according to a setting value, deterioration of the signal input and output between the signal processing device and the transmitting and receiving device via the electric connector; a memory configured to store first characteristic data indicating a transmission characteristic of the signal in the electric connector; and a second processor configured to acquire, from the transmitting and receiving device, second characteristic data for indicating a transmission characteristic of the signal in the transmitting and receiving device and set the setting value in the first processor based on the first characteristic data and the second characteristic data.

Signal processing device, transmitting and receiving device, and signal processing method

An optical transmission device includes an optical modulator and a processor. The optical modulator optically modulates an optical signal with a driving signal to output a modulated optical signal. The processor performs ABC on a bias of the optical modulator, using the modulated optical signal, so as to cause the bias to converge to an optimum point. The processor starts the ABC using a modulated optical signal optically modulated with a QPSK signal at start-up timing, acquires an optimum value that is a bias value when the bias converges to the optimum point, and stops the ABC. After the ABC is stopped, the processor sets the acquired optimum value as an initial value, and restarts the ABC using a modulated optical signal optically modulated with an N-QPSK signal.

Optical transmission device, optical modulator, and bias control method

An optical receiver includes: a frontend circuit configured to generate a baseband signal representing a received optical signal by using local oscillator light; a frequency offset estimator configured to estimate a frequency offset of the baseband signal; a frequency offset corrector configured to correct the frequency offset of the baseband signal according to an estimation result by the frequency offset estimator; a phase recovery configured to recover a modulated phase from the baseband signal for which the frequency offset is corrected; a data recovery configured to recover transmission data according to the modulated phase recovered by the phase recovery; and a controller configured to control an operation of the frequency offset estimator according to a phase error of the baseband signal for which the frequency offset is corrected.

Optical receiver and frequency offset correction method

A communications apparatus includes a transmitter that transmits signal light that is wavelength division multiplexed with other signal light and that is to be transmitted to an opposing apparatus, and a processor that is operative to change a frequency of the signal light to be transmitted by the transmitter based on detection results at the opposing apparatus and concerning variation in the frequency of the transmitted signal light.

Communications apparatus, multiplex communications apparatus, communications system, and communication method

An optical dispersion compensator including a first optical device in which light inputted from a first port is outputted from a second port and light inputted from the second port is outputted from a third port, an optical filter type dispersion compensation device that receives light from the second port of the first optical device and compensates wavelength dispersion with respect to the received light, and a second optical device that includes a fourth port to which light is inputted from the optical filter type dispersion compensation device, and in which the light inputted from the fourth port is outputted from a fifth port and light inputted from a sixth port is outputted from the fourth port.

Optical dispersion compensator, optical transmission apparatus, optical transmission system, and method thereof

An optical amplifying apparatus has a plurality of pumping sources generating pumping light beams at different wavelengths, a Raman amplification medium receiving the pumping light beams from the pumping sources to amplify a main signal light beam by using stimulated Raman scattering phenomenon due to the pumping light beams, a rare-earth-doped optical amplification medium receiving the main signal light beam amplified by the Raman amplification medium to further amplify it, and a pumping light introducing means introducing a part or all of a pumping light beam at a specific wavelength of the pumping light beams as a pumping light beam for the rare-earth-doped optical amplification medium to the rare-earth-doped optical amplification medium. The optical amplifying apparatus in a smaller size and with less fluctuation in the optical output power can readily send monitoring control information irrespective of presence of the optical input power.

Optical amplifying apparatus which routes pumping light to a raman amplification medium and a rare-earth-doped optical amplification medium

A method includes taking backscattering light of a first wavelength in a first direction of a first transmission line and coupling the same so that the light may travel in a second direction of a second transmission line; taking a second wavelength in the first direction of the first transmission line and coupling the same so that the second wavelength may travel in the first direction of the second transmission line; taking backscattering light of the first wavelength in the second direction of the second transmission line and coupling the same so that the backscattering light may travel in the first direction of the first transmission line; taking the second wavelength in the second direction of the second transmission line and coupling the same so that the second wavelength may travel in the second direction of the first transmission line.

Growing community of inventors

Kawasaki, Japan

Hiroshi Ogiwara