Yokogawa Electric Corporation

Other

Shinji Iio

Akira Miura

Morio Wada

Tsuyoshi Yakihara

Masayuki Suehiro

Chie Sato

Sadaharu Oka

Shinji Kobayashi

Katsuya Ikezawa

Yoshiyuki Asano

Daisuke Hayashi

Shinichi Nakajima

Shin-ichi Nakajima

Hirotoshi Kodaka

Mamoru Hihara

Yasukazu Akasaka

Tadashige Fujita

Machio Dobashi

Yasuyuki Suzuki

Akira Toyama

Yoshihiro Sanpei

Toshimasa Umezawa

Hiroshi Shimizu

Shoujirou Araki

Kazuhisa Yamamoto

Yasuo Kitaoka

Takeshi Inoue

Hiroshi Sugawara

Hiroyuki Matsuura

Takahiro Kudo

Takashi Mogi

Takaaki Hirata

Koki Iemura

Toshimichi Suzuki

Kanji Tatsumi

Toshiyasu Izawa

Shun-ichi Miyazaki

Naoaki Machida

Shigeo Uneme

An interferometer of the invention includes: a first splitting element which includes a first transparent medium and a first splitting film formed on the first transparent medium, and which splits incident light into a first split beam and a second split beam, the first split beam being the incident light reflected by the first splitting element and the second split beam being the incident light transmitted through the first splitting element; and a second splitting element which includes a second transparent medium and a second splitting film formed on the second transparent medium, and which causes interference between the first split beam and the second split beam passed through different optical paths, the second splitting element being positioned such that a positional relationship between the second transparent medium and the second splitting film with respect to a direction of incidence on the second splitting element of the first split beam is opposite to a positional relationship between the first transparent medium and the first splitting film with respect to a direction of incidence of the incident light on the first splitting element.

Interferometer, demodulator, and splitting element

An interferometer of the present invention includes: a splitting element which splits an incident light beam into a first split beam and a second split beam; and a first phase compensator which is positioned in an optical path of the first split beam, and which compensates a phase difference occurring between the first split beam and the second split beam upon splitting of the incident light beam by said splitting element.

Delayed interferometer enabling a reduction of polarization-dependent frequency shift and demodulator

An optical packet network system of a ring type, capable of preventing degradation of an optical signal, can be implemented by providing a mechanism relatively simple in structure, capable of erasing light noise if the optical packet signal does not exists. In the optical packet network system made up by interconnecting respective nodes adjacent to each other, and connecting a sending source of an optical packet signal to a ring, a light noise removal function block is provided between the respective nodes adjacent to each other.

Optical packet network system

An optical communication apparatus includes an erbium-doped optical fiber amplifier for amplifying a modulated optical signal, wherein a light which is not modulated is inputted to the erbium-doped optical fiber amplifier together with the optical signal.

Optical communication apparatus

An address recognition apparatus may include a first normalizing unit, a second normalizing unit and an address determination unit. The first normalizing unit normalizes a first electric signal and generates a first normalized signal, wherein the first electric signal is associated with a first divided set of optical packet signals. The second normalizing unit normalizes a second electric signal and generates a second normalized signal, wherein the second electric signal is associated with a second divided set of optical packet signals. The address determination unit refers to the first and second normalized signals and determines whether a destination address of a set of optical packet signals is identical to or different from an address allocated to a self-station associated with the address recognition apparatus, wherein the set of optical packet signals has been divided into the first and second divided sets of optical packet signals.

Address recognition apparatus

A semiconductor optical switch may include an optical waveguide, a first electrode, and a first reflector. The optical waveguide may include a branching point, a first incoming path and first and second outgoing paths. The first electrode is provided at the branching point to give carrier injection into the branching point to allow that the branching point reflects an optical signal that is propagating through the first incoming path so that the reflected optical signal propagates through the second outgoing path. The first electrode may give no carrier injection into the branching point to allow that the branching point allows the optical signal to transmit through the branching point and propagate through the first outgoing path. The first reflector is provided on the first outgoing path. The first reflector reflects a leakage of light that has propagated from the branching point.

Semiconductor optical switch

A clock reproducing apparatus includes a clock reproducing circuit having: a gated oscillator having an oscillating circuit of two routes; and a frequency control circuit for comparing a phase of an output of the gated oscillator with a phase of a reference clock, and supplying a phase control signal to the gated oscillator based on the comparison result so as to set a delay time, input data is input to a reset input terminal of the gated oscillator, and different route of the two routes of the oscillating circuit operates depending on a case where the input data is 'H' and a case where the input data is 'L'.

Clock reproducing apparatus

An optical waveform shaping device includes a first waveguide portion, formed on a substrate, for transmitting the optical signal and simultaneously absorbing a portion of the optical signal, which has a signal level equal to or smaller than a predetermined value, so as to shape the optical signal; and a second waveguide portion, formed on the substrate, for transmitting the optical signal, which was transmitted through the first waveguide portion, and simultaneously amplifying the optical signal. The first waveguide portion may be formed using a saturable absorber. A first electrode for supplying electric current to the first waveguide portion so that the first waveguide portion is provided with a function of absorbing the optical signal; and a second electrode for supplying electric current to the second waveguide portion so that the second waveguide portion is provided with a function of amplifying the optical signal may also be provided.

Optical waveform shaping device including portions for respectively absorbing and amplifying transmitted optical signal

Disclosed is a repeater including: a recognizing unit to recognize a destination address of an optical packet from the optical packet which includes the destination address assigned in unit of bit and a bit indicating whether or not a plurality of destination addresses are assigned; an optical splitting unit to split the optical packet into a plurality of optical packets; and selecting units to select transmission channels for the split optical packets on the basis of recognition results by the recognizing units, respectively.

Repeater and optical communication system

An optical logic device performs a logic operation on a plurality of input light signals. The optical logic device has a photoelectric conversion portion, in which photoreceivers for receiving input light signals are provided in parallel, that outputs an electric signal obtained by adding up outputs of the photoreceivers, and a comparator that compares a voltage level of the electric signal outputted from the photoelectric conversion portion with a predetermined voltage level.

Optical logic device responsive to pulsed signals

There is provided a PD-TIA module that can be used for recognition of an address of an optical packet signal in a system having variation in mark rate all the time, such as an optical packet communication system. An optical communication module comprises a photoelectric converter for converting an optical signal into a current signal, a current/voltage conversion means connected to the photoelectric converter, for converting the current signal into a voltage signal, and a limiting amplifier for receiving and amplifying an electric signal subjected to voltage conversion by the current/voltage conversion means while comparing the electric signal as amplified with a predetermined threshold value, thereby outputting a signal for '0' or '1'.

Optical packet communication device with an applied negative voltage for canceling an offset voltage

An optical switch changes over transmission paths of an optical signal by a refractive index change. The optical switch has an optical waveguide layer having an optical waveguide whose output path of an optical signal branches into two, and reflection diffusing ditches which are provided in a portion outside the optical waveguide in the optical waveguide layer, wherein the portion is closed to a branch portion of the optical waveguides. The reflection diffusing ditches extend in a direction crossing a traveling direction of the optical signal.

Optical switch

A light signal switching apparatus has an input port and output ports, and outputs an output light from a desired output port. The apparatus has a splitter polarizing an input light into first and second polarized light whose polarization planes are different mutually by 90 degrees, a first polarization controller rotating a polarization plane of the second polarized light by 90 degrees to output a third polarized light, a first optical switch switching a path of the first polarized light to the desired output port side, a second optical switch switching a path of the third polarized light to the desired output port side, a second polarization controller rotating a polarization plane of the first polarized light by 90 degrees to output a fourth polarized light, and a combiner combining the third polarized light with the fourth polarized light, to output a combined light to the desired output port.

Light signal switching apparatus

An optical switch in which the adverse effect of heating can be restrained is realized. An optical switch for switching a transmission path of an optical signal by a change in refractive index due to carrier injection comprises: a semiconductor substrate; an optical waveguide layer which is formed on the semiconductor substrate and in which an optical waveguide is formed, the optical signal being incident on the optical waveguide from one side, then branched into two at a halfway part and emitted from the optical waveguide; a first electrode formed on the optical waveguide layer and at a branching part of the optical waveguide; a second electrode formed on the optical waveguide layer and near the branching part of the optical waveguide; and a third electrode formed on the optical waveguide layer and on a side opposite to the first electrode as viewed from the second electrode; wherein when the optical switch is on, carriers are injected from the first and second electrodes, and when the optical switch is off, carriers are injected from the second and third electrodes.

A photoelectric apparatus has a phototransistor which receives a light signal and in which a collector current thereof varies according to intensity of the received light signal, and a transistor in which a collector current thereof varies according to a base voltage thereof. The phototransistor and the transistor constitute a differential amplification circuit. At least one of the phototransistor and the transistor outputs an electric signal.

Growing community of inventors

Tokyo, Japan

Shinji Iio