Fujitsu Corporation

Other

Miki Onaka

Yasushi Sugaya

Etsuko Hayashi

Susumu Kinoshita

Tomoto Tanaka

Kiyotoshi Noheji

Masanori Kondoh

Togo Fukushi

Hiroshi Onaka

Norifumi Shukunami

Masato Nishihara

Yuichi Suzuki

Hiroaki Tomofuji

Manabu Watanabe

Satoru Okano

Ichiro Nakajima

Takehiro Fujita

Takahumi Terahara

Hisao Nakashima

Hiroki Ooi

Hideyuki Miyata

Terumi Chikama

Toshihiro Ohtani

Tadashi Okiyama

Tsukasa Takahashi

Masahiro Yuki

Ryosuke Goto

Shinichirou Muro

Hideaki Sugiya

Tatsuya Tsuzuki

Hiroyuki Itou

Taiki Kobayashi

Chihiro Ohshima

Mayumi Naito

Taichi Ueki

Kazuto Imai

Yuya Osumi

Jun Okabe

Takashi Hayasaka

An optical module includes a light source; a demultiplexer configured to demultiplex a light into a transmission light and a local light; an optical modulator; an excitation light source; an optical waveguide substrate that includes: a polarization beam splitter configured to split a reception light into an X-polarized component and a Y-polarized component, a beam splitter, a pair of optical hybrid circuits configured to cause the X-polarized component and the Y-polarized component to interfere with the local light split by the beam splitter, a pair of local light waveguides configured to couple the beam splitter and the pair of optical hybrid circuits, a pair of reception light waveguides configured to couple the polarization beam splitter and the pair of optical hybrid circuits, wherein the pair of local light waveguides and the transmission light waveguide are doped with a rare-earth ion that amplifies a light when the excitation light is introduced.

Optical module and method for controlling optical module

An optical transmission device as the first optical transmission device includes a light source to output light, an optical transmitter to transmit first information regarding a reception characteristic and power consumption of the first optical transmission device to a second transmission device, an optical receiver to receive second information regarding a reception characteristic and power consumption of the second optical transmission device, an optical branching circuit to branch the light output from the light source into transmission light for the optical transmitter and local light for coherent reception by the optical receiver, and vary power of the transmission light and power of the local light individually, and a processor to control a driving condition of the optical branching circuit, based on the first information and the second information, the power of the transmission light and the power of the local light varying in accordance with the driving condition.

Optical transmission device and optical communication system

A polarization reducing apparatus includes a separating unit configured to separate input light into components having polarization directions orthogonal to each other; a winding waveguide of silicon formed on a silicon substrate in a winding manner, the winding waveguide transmitting a first component among the components separated by the separating unit; an optical path configured to have a shorter optical path length than the winding waveguide, the optical path transmitting a second component among the components separated by the separating unit; a combining unit configured to combine the first component and the second component; and an output unit configured to output light consisting of the first component and the second component combined by the combining unit.

Polarization reducing apparatus, light source apparatus, optical amplifying apparatus, and excitation light source apparatus for raman amplification

A variable optical attenuator includes: a transparent medium configured to transmit light; a first reflective film formed on a light incidence surface of the transparent medium; a second reflective film formed on a light emission surface of the transparent medium; and a resonance length variable medium configured to vary an optical resonance length between the first reflective film and the second reflective film, wherein the first reflective film has a first reflectivity at which at least one of light of a first wavelength and light of a second wavelength is partially transmitted through the first reflective film, the at least one of light being the light of the first wavelength, and wherein the second reflective film has a second reflectivity lower than the first reflectivity for the light of the first wavelength and a third reflectivity lower than the second reflectivity for the light of the second wavelength.

Variable optical attenuator and optical module

An optical device includes a first fiber; a liquid crystal member configured to have liquid crystal pixels that reflect light output from the first fiber; a second fiber configured to have a core to which a first order light ray in the light reflected by the liquid crystal member is optically connected; a light receiving circuit configured to receive higher order light rays in the light reflected by the liquid crystal member; and a control circuit configured to control based on a light receiving result of the light receiving circuit, efficiency of optical connection of the first order light ray to the core of the second fiber, by varying an angle of the light reflected by the liquid crystal member.

Optical device

An optical amplification repeater includes a first rare-earth-doped optical amplification medium which amplifies a first signal light to be transmitted to a downstream, a second rare-earth-doped optical amplification medium which amplifies a second signal light to be transmitted to an upstream, and a pump light split and guide unit configured to split a pump light transmitted together with any of the first and second signal lights and to guide the split pump light to each of the first and second rare-earth-doped optical amplification mediums.

Optical amplification repeater and optical transmission station

An amplifying apparatus includes an optical fiber that includes a wound portion doped with a rare earth element and three-dimensionally wound, holes being formed in cladding of the optical fiber and surrounding a core of the optical fiber, the optical fiber transmitting signal light injected thereinto; a thermally conductive member in which the wound portion of the optical fiber embedded, the thermally conductive member having thermal conductivity; a light source that emits excitation light; an injecting unit that injects the excitation light emitted by the light source, into the optical fiber; and a temperature adjusting unit that includes a thermal coupling unit thermally connected to the light source and the thermally conductive member, the temperature adjusting unit adjusting a temperature of the thermal coupling unit.

Amplifying apparatus and amplifying medium

An optical transmission medium includes: a plurality of cores; a first cladding that covers each of the plurality of cores; a second cladding that covers a plurality of first claddings; and a reflection layer that covers the second cladding and has reflection characteristics with respect to a wavelength band of multimode light.

Optical transmission medium and optical amplifier

An optical transmitting device includes: a laser diode to which a first or second driving current is provided; a controller to provide the laser diode with the first driving current to transmit an optical signal and with a plurality of second driving currents, to emit light, different from each other in magnitude during a stop of providing the first driving current; a measuring unit to measure an intensity of the light emitted by the laser diode; a calculator to calculate a threshold current of the laser diode, based on the intensities corresponding to the plurality of second driving currents measured by the measuring unit and magnitudes of the plurality of second driving currents; and a determination unit to determine a precursor of a sudden-death of the laser diode, based on an amount of variation in the threshold current calculated by the calculator during a specific period.

Optical transmitting device and optical transmission system

An amplification apparatus includes: a circulator to receive, at a first terminal, first signal light transmitted from OLT to ONU and first light having a predetermined wavelength different from the first signal light and, at a third terminal, second signal light transmitted from ONU to OLT and second light having the predetermined wavelength; a first reflector to output reflected light back to a second terminal; a first optical amplifier to have an amplification band characteristic of amplifying at least the first signal light; a second reflector to output reflected light back to a fourth terminal; a second optical amplifier to have an amplification band characteristic of amplifying the second signal light without amplifying the second light having the predetermined wavelength; and a first partial reflector to have a wavelength transmission characteristic of outputting the light having a wavelength different from the predetermined wavelength to the second optical amplifier.

Amplification apparatus and communication system

An optical delay device includes an optical path in which an input optical signal travels the same path recursively; an optical switch that switches between an output state of outputting the optical signal input to the optical path, and a non-output state of not outputting the optical signal input to the optical path; and a controller that sets the optical switch to the non-output state until a point in time when a given delay time elapses since input of the optical signal to the optical path and at the point in time when the given delay time elapses, switches the optical switch to the output state.

Optical delay device, optical circuit, and optical delay method

An optical communication system, where in an optical transmission apparatus arranged on a transmission side of respective repeating sections, an OSC optical amplifier is provided on an OSC light optical path between from an OSC transmitter to a multiplexer, and the OSC optical amplifier is controlled so that the power of OSC light transmitted on the transmission path becomes a previously set target value. As a result the OSC light is amplified by a different amplifying device to that for the main signal lights at the time of transmission. Therefore even in the case where the span losses are large, OSC light can be reliably received by the optical transmission apparatus on the reception side.

Optical transmission apparatus and optical communication system

An optical amplifier that amplifies signal light with Raman amplification in the Raman amplification medium. The optical amplifier includes a light source that supplies pump light into the Raman amplification medium, a first detector that detects input power of the pump light to be input to the Raman amplification medium, a second detector that detects output power of the pump light output from the Raman amplification medium, and a processor operable to calculate transmission loss of the pump light in the Raman amplification medium by comparing the input power with the output power, and calculate transmission loss of the signal light in the Raman amplification medium based on the transmission loss of pump light corrected based on a wavelength of the signal light and a wavelength of the pump light.

Optical amplifier and transmission loss measurement method

An optical amplifying device includes a first optical amplifier for amplifying signal light; a second optical amplifier serially connected with the first optical amplifier; an optical device for compensating deterioration of the signal light, the optical device arranged between the first optical amplifier and the second optical amplifier; a variable optical attenuator for attenuating the signal light, the variable optical attenuator arranged between the first optical amplifier and the second optical amplifier; a first automatic level controller for detecting a second amplifier output power and for controlling driving status of the second amplifier in a predetermined output power level; and a first automatic gain controller for detecting an input power of the second optical amplifier and an output power of the second optical amplifier, and for controlling an optical attenuation value of the variable optical attenuator.

Growing community of inventors

Kawasaki, Japan

Miki Onaka