Fujitsu Corporation

Yokogawa Electric Corporation

Hitachi Cable, Inc.

Akihiko Isomura

Jens Rasmussen

Takafumi Terahara

Akira Miura

Hiroki Ooi

Yuichi Akiyama

George Ishikawa

Takeshi Hoshida

Zhenning Tao

Noriaki Mizuguchi

Kenichi Kaburagi

Yasuyuki Suzuki

Hiroshi Onaka

Kentaro Nakamura

Hiroyuki Matsuura

Morio Wada

Hideaki Arai

Takashi Toyomaki

Eiji Ishikawa

Yoshikazu Terayama

Satoshi Takasugi

Jens C Rasmussen

Zhenning c/o Fujitsu Research And Dev Cent Co Ltd Tao

An optical add/drop multiplexer includes a first optical coupler receiving an optical signal including a plurality of multiplexed wavelengths, a wavelength blocker receiving the optical signal from the first optical coupler, and blocking at least one wavelength of the plurality of multiplexed wavelengths, a first wavelength selective switch, having one input port receiving the outputted optical signal from the first optical coupler and a plurality of output ports, demultiplexing a plurality of arbitrarily selected multiplexed wavelengths from the received optical signal, a second wavelength selective switch, having a plurality of input ports, each input port receiving a different optical signal and one output port, multiplexing a plurality of arbitrarily selected wavelength signals on the plurality of input ports, and a second optical coupler receiving the optical signal output from the wavelength blocker and multiplexed wavelength signal from the second wavelength selective switch.

Optical add/drop multiplexer

Influence of polarization mode dispersion, occurring in an optical fiber is mitigated by means of polarization scrambling, differential group delay which a received optical signal has is optically suppressed; the optical signal in which differential group delay is thus suppressed is converted into an electric signal; and error correcting processing is carried out on the electric signal obtained, a jitter amplitude in the received optical signal is suppressed, influence of which to a jitter tolerance increases due to increase in speed of the polarization scrambling.

Optical signal transmission system and optical signal transmission method

I branch is provided with a first interferometer, a first balanced optical detector, and a first data recovery circuit. Q branch is provided with a second interferometer, a second balanced optical detector and a second data recovery circuit. In I branch, a mixer multiples input signal of the first data recovery circuit with output signal of the second recovery circuit. An averaging circuit averages output signal of the mixer. In Q branch, a mixer multiples input signal of the second data recovery circuit with output signal of the first recovery circuit. An averaging circuit averages output signal of the mixer. A first phase control apparatus controls the phase of a phase shifter comprised in the first interferometer based on the output signal of the averaging circuit. A second phase control apparatus, in the same manner, controls the phase of a phase shifter comprised in the second interferometer.

Phase monitor apparatus, phase control apparatus and methods thereof for optical DQPSK receiver

An interferometer for demodulating a differential M-phase shift keying signal includes a PLC type interferometer main body, a heating portion that heats the PLC type interferometer main body, and an intermediate member having a higher stiffness than that of the PLC type interferometer main body, for bonding the PLC type interferometer main body and the heating portion with each other while being sandwiched therebetween. A linear expansion coefficient difference between the PLC type interferometer main body and the intermediate member is equal to or smaller than 4.5&#xd7;10/&#xb0; C., and a thermal conductivity difference between the PLC type interferometer main body and the intermediate member is equal to or larger than 10 W/mK. A phase of an optical signal flowing through the interferometer is adjusted by using the heating portion and a second heating portion.

Interferometer for demodulating differential M-phase shift keying signal

A core unit arranged in a transmission path includes a through path for causing an input signal to an input port to pass through to an output port, a drop-side portthat drops the input signal having a predetermined wavelength, and an add-side portthat adds channel having a predetermined wavelength to the input light.

The optical node connects N networks to each other (where N is an integer larger than one). Each of the N networks respectively includes a first transmission path and a second transmission path. The optical node includes a switching unit that connects the first transmission path of one network of the N networks to other (N&#x2212;1) networks; a failure detector that detects failure in the first transmission path of the network; and a control unit that causes the switching unit to connect the second transmission path of the network to the other (N&#x2212;1) networks when the failure is detected.

Optical node and optical add/drop multiplexer

In the optical reception apparatus, a DQPSK polarization multiplexed signal light (S) input thereto is split into horizontally/vertically polarized signal lights (S, S) by a polarization beam splitter (), and the signal lights (S, S) each is branched into two by each of optical couplers (). Then, one branched lights (S, S) by each of the optical couplers () are supplied to a delay interferometer () on the I branch via optical circulators () to be propagated in bidirectional, and the other branched lights (S, S) by each of the optical couplers () are supplied to a delay interferometer () on the Q branch side via optical circulators () to be propagated in bidirectional, so that a set of delay interferometers () is commonly used for horizontally polarized waves and vertically polarized waves.

Optical reception apparatus compatible with DQPSK polarization multiplexing format

A calculation processing unit controls temperature of a Peltier device based on a slope of a waveform obtained by subtracting a waveform of a B-arm monitoring signal from a waveform of an A-arm monitoring signal and a value obtained by subtracting a value B of the B-arm monitoring signal from a value A of the A-arm monitoring signal. Similarly, the calculation processing unit controls a phase of the A-arm and a phase of the B-arm. An A-arm side micro-controller controls temperature of an A-arm side heaterbased on the value of the A-arm monitoring signal, and controls the phase of the A-arm. A B-arm side micro-controller controls temperature of a B-arm side heater based on the value B of the B-arm monitoring signal, and controls the phase of the B-arm.

Phase control apparatus and optical DQPSK receiver

Branches are grouped into a groupincluding first and second branches, and a groupincluding third and fourth branches. The signal after being passed through a dual pin photodiode in one branch included in the groupand being at the earlier stage of a CDR circuit is obtained. Also, from the later stage of the CDR circuit in the other branch in the groupis obtained. The obtained signals are passed through low pass filters, and an average value over a plurality of symbols is obtained. The signal from the earlier stage of the CDR circuit is multiplied by the signal from the later stage, and they are averaged. The obtained value reflects the phase difference of the two delay interferometers in the group. The groupis monitored by using the same method.

Phase monitor used in optical receiver

By comprising a unitmaking the adjustment related to degradation compensation of a plurality of signals with each wavelength made after multiplexing the signals, a unitmultiplexing the outputs of a plurality of units, a unitcompensating for the waveform degradation of the output of the unit, a unitselecting a component with one of a plurality of wavelengths from a part of the output of the unitand a unitdetecting the degree of signal degradation from the output of the unitand controlling the adjustment by the unitcorresponding to the selected frequency so as to reduce the degree, components disposed for each wavelength in an optical transmission system adopting a wavelength-division multiplexing method can be shared, and the size and cost of an compensator can be reduced.

Optical signal degradation compensator

An amount of change of a control signal applied to a polarization controller in a polarization mode dispersion compensator is determined for each feedback loop by evaluating degree of polarization response in past feedback loops.

Polarization mode dispersion compensator and polarization mode dispersion compensating method

A wavelength-division multiplexing transmitter that is capable of enhancing its ability to compensate for a difference in light intensity between wavelengths. The wavelength-division multiplexing transmitter includes an optical branching part for branching a wavelength-division multiplexed input optical signal into a plurality of optical signals, a plurality of wavelength-selective devices for selecting as output wavelengths the wavelengths of each of the optical signals branched by the optical branching part, and an optical coupling part for coupling the output wavelengths respectively output from the plurality of wavelength-selective devices. At least either the branching in the optical branching part or the coupling in the optical coupling part is performed at a power ratio M:N where M and N differ from each other.

Growing community of inventors

Kawasaki, Japan

Akihiko Isomura