Nec Corporation

Nissan Motor Company Limited

Fujitsu Corporation

Fujitsu Microelectronics Limited

Jidosha Denki Kogyo Kabushiki Kaisha

Canon Kabushiki Kaisha

Ricoh Company, Ltd.

Tdk Corporation

Renesas Technology Corp.

Jidosha Denki Kogyo K.k.

Sun Top Techno Co., Ltd.

Kouichi Suzuki

Kazuyuki Mori

Kiyoshi Konishi

Masao Morie

Eisaku Hori

Toshio Iwaoka

Isao Yamamoto

Hiroyuki Yamazaki

Makoto Yoshida

Satoru Sekiguchi

Masayuki Kokado

Norihito Miyoshi

Juniti Yamaguchi

Youko Yaguchi

Sadanobu Sato

Yumiko Yamashita

Hiroshi Inoue

Masaru Ikebe

Kiyoshi Suzuki

Noboru Murayama

Toshihiro Kikuchi

Yukio Miyazaki

Yoshikazu Inoue

Hiroyuki Nomura

Yoshiyuki Etoh

Yutaka Urino

Tetsuro Kanemaru

Kinichiro Nakano

Kyoji Kobayashi

Tomoyuki Okada

Kiyoshi Yoshida

Yuichi Yamaguchi

Tadahiko Hanada

Takahisa Ito

Seiji Makino

Katsuji Tabara

Hisamasa Yano

Kumi Ito

Shigeki Oouchi

Yuuichi Yamaguchi

Takanori Okita

Syuji Katase

Kenji Chichii

In a coherent optical receiver device, the dynamic range considerably decreases in the case of selectively receiving the optical multiplexed signals by means of the wavelength of the local oscillator light, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; and a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; wherein the coherent optical receiver includes a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; and the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal.

Coherent optical receiver device and coherent optical receiving method

A coherent optical module includes an optical power monitor configured to monitor power of a wavelength multiplexed signal, a local oscillator configured to output a local oscillation light with an optical power corresponding to the monitored power of the wavelength multiplexed signal, a coherent receiver configured to receive an optical signal from the wavelength multiplexed signal by an interference with the local oscillation light, and a converter configured to convert the received optical signal to an electrical signal.

A coherent optical receiver device includes a first unit configured to output local oscillation light having a predetermined wavelength, a second unit configured to receive an optical signal to have been inputted by making the optical signal interfere with the local oscillation light, a third unit configured to process electrically the optical signal received by the second unit, a fourth unit configured to monitor at least a part of power of the optical signal, and a fifth unit configured to control power of the local oscillation light output by the first unit depending on an optical power monitored by the fourth unit.

In a receiver, a reception front end receives a polarization-scrambled polarization multiplexed optical signal, polarization-separates the received polarization multiplexed optical signal, and converts each signal into quantized signals. A digital signal processor samples the quantized signals, demodulates the signals by using a polarization separation digital signal processing algorithm, and outputs demodulated signals. When phase and amplitude variations of the demodulated signals are greater than a predetermined value, a control circuit causes the digital signal processor to interrupt processing using the polarization separation digital signal processing algorithm, changes an initial value of a filter coefficient, and then causes the digital signal processor to start the processing using the polarization separation digital signal processing algorithm.

Receiver, transmission system, method for receiving polarization multiplexed optical signal, and non-transitory computer readable medium storing receiver control program

An object of the invention is to provide an optical transmission apparatus capable of reducing the influence of nonlinear effect of an optical fiber, suppressing a band requested to a device from being widened, easily bias controlling a modulator, and flexibly switching plural modulation methods. An optical transmission apparatusaccording to the invention includes a modulatorand a controller. The modulatoris a modulator capable of quadrapture phase-shift keying the light from a light source and outputting the light. The controllercontrols the input signal to the modulatorand causes the modulatorto carry out a quadrapture phase-shift keying operation or a &#x3c0;/2 shift binary phase-shift keying operation.

Optical transmission apparatus, optical transmission method and program for optical transmission

In an optical transmission system using an RZ code, in order to improve the quality of the modulated transmission signal, an RZ optical modulator includes an RZ carver that outputs a optical pulse train of the RZ code, a polarization adjustment device which improves and outputs a polarization extinction ratio of optical pulse train outputted from the RZ carver and an optical modulator which modulates and outputs the optical pulse train outputted from a polarization adjustment device.

RZ optical modulator and RZ optical modulation method

In a coherent optical receiver device, the control process for keeping received signals in high quality is complicated, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving input signal light; an input power monitor obtaining input power information determined on the basis of the power of the input signal light; a local oscillator connected to the coherent optical receiver; and a controller connected to the coherent optical receiver, the input power monitor, and the local oscillator; wherein the coherent optical receiver comprises a 90-degree hybrid circuit, a photoelectric converter, and an amplifier; the input power monitor is disposed in the optical path of the input signal light in a stage preceding the amplifier; and the controller obtains the input power information from the input power monitor and controls the power of local oscillation light output from the local oscillator on the basis of the input power information.

A PLL circuit includes a storage unit for storing a control voltage at a desired frequency obtained when a reference signal is synchronized with a referenced signal; a current generator circuit that includes a pull-up circuit and a pull-down circuit, each of which outputs an electric current at a predetermined timing; a voltage detecting unit that detects an output voltage corresponding to an electric current output by the current generator circuit; and a current control unit that changes a current value of at least one of the pull-up circuit and the pull-down circuit so that respective current values match each other, and controls the respective current values of the pull-up circuit and the pull-down circuit so that the output voltage detected by the voltage detecting unit matches the control voltage stored in the storage unit.

Oscillator circuit and electric-current correction method

The object is to provide a highly reliable, high-performance, and low-price tunable light source and the like. The present invention comprises: a multiple resonator that oscillates with a wavelength where frequencies of three or more resonant elements with shifted cycles intersect; and a tunable device for controlling the resonant wavelength of the multiple resonator by simultaneously changing the respective optical path lengths of the plurality of resonant elements constituting the multiple resonator. The multiple resonator has a structure in which three resonant elements are connected in series; and provided that the optical path lengths of the resonant elements are L, L, L, Vernier orders are M&#x3e;1, M&#x3e;1, the optical path lengths are defined as phase amount 'P' is the changed optical path length standardized by one-wavelength of the optical path length, and the respective phase amount 'P' of the two ring resonant elements whose optical path lengths are to be changed are defined as &#x201c;P&#x201d; and &#x201c;P&#x201d;, the tunable device controls the increase/decrease amount of the phase amount &#x201c;P&#x201d; and &#x201c;P&#x201d; based on a linear function with a slope of 

Tunable resonator, tunable light source using the same, and method for tuning wavelength of multiple resonator

A multiphase clock generator circuit for generating a plurality of output clock pulses that differ in phase on the basis of a reference clock pulse, has first and second divider circuits for dividing first and second reference clock pulses that differ in phase to generate output clock pulses, and a switch for forming an intermittent short between predetermined nodes of the first and second divider circuits, wherein the switch forms a short between the predetermined nodes with timing in which the predetermined nodes are brought to the same level in a normal operating state.

Multiphase clock generator circuit

Growing community of inventors

Tokyo, Japan

Kouichi Suzuki