Yokogawa Electric Corporation

Masayuki Suehiro

Shinji Iio

Akira Miura

Morio Wada

Tsuyoshi Yakihara

Yoshiyuki Asano

Shinji Kobayashi

Daisuke Hayashi

Chie Sato

Sadaharu Oka

Katsuya Ikezawa

Shinichi Nakajima

Shin-ichi Nakajima

Hirotoshi Kodaka

Yasukazu Akasaka

Mamoru Hihara

Toshimasa Umezawa

Hiroshi Shimizu

Machio Dobashi

Shoujirou Araki

Hiroyuki Matsuura

Akira Toyama

Takahiro Kudo

Takashi Mogi

Tadashige Fujita

Naoaki Machida

Kanji Tatsumi

Toshiyasu Izawa

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

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.

An optical switch has an input port, output ports, optical waveguides whose output path of an optical signal branch into two. A first stage optical switch section is provided in a branching portion of the optical waveguide, which switches a propagating path of an optical signal to a path leading to the desired output port. A subsequent stage optical switch section is provided in a branching portion of the optical waveguide subsequent to the first stage optical switch section, which switches a propagating path of a leakage light, which is leaked from the first stage optical switch section, to a path which does not propagates the leakage light to any of the output ports. The first stage optical switch section and the subsequent stage optical switch section switch a path of an optical signal according to a refractive index change caused by a carrier injection.

An address determination circuit makes an address determination of an optical packet to which a destination address and a source address are assigned on a bit-by-bit basis. The address determination circuit has an optical branching section which divides the optical packet into branches, in which each of the branched optical packet contains the same original data, a delay section which delays at least one of the branched optical packets, a bit determination section which determines each bit value of the branched optical packets, and a logic operation section which performs a logic operation on the bit values of the branched optical packets determined by the bit determination section. The delay section delays the branched optical packets so that the logic operation section performs the logic operation on a bit assigned the destination address or the source address and a bit having a predetermined bit value in synchronization with each other.

Address determination circuit and optical communication system

A matrix optical switch that can switch the transmission path of an optical signal without requiring a driving unit for each optical switch is realized. A matrix optical switch for switching a transmission path of an optical signal by connecting plural input sides and plural output sides, respectively, comprises: a semiconductor optical waveguide substrate; a photo mask choosing system for selecting and arranging one photo mask from plural photo masks each of which has printed thereon a pattern connecting plural input sides to plural output sides; and a light source for casting output light having larger energy than a band gap of the semiconductor optical waveguide substrate onto a photon injection area between the plural input sides and the plural output sides on the semiconductor optical waveguide substrate via the selected photo mask.

Optical switch matrix

The present invention aims at achieving an optical signal processing system which converts a higher speed optical signal to electrical signals by time-demultiplexing the signal with low-speed electrical signals. The present invention offers an improved optical signal processing system that converts a serial pulse train optical signal with transmission speed N to parallel pulse train electrical signals. This system is characterized by providing a serial-parallel converter in which at least two optical switches are cascaded, each of which outputs optical signals with transmission speed M (N&#x3e;M) to one of the two output terminals and outputs the remaining optical signals to the alternative one of said two output terminals by switching connection to said output terminal, receiving parts which convert optical signals from one of the two output terminals of each of the above optical switches to electrical signals, a synchronizing circuit which outputs timing signals in synchronization with electrical signals output from these receiving parts, and drivers which cause the above described optical switches to switch their connections based on timing signals output from the above synchronizing circuit.

Optical signal processing system

In an optical switch, a carrier-accumulating layer in which injected carriers are accumulated is provided on a semiconductor substrate having a waveguide formed thereon so that injected effective carriers tend to be accumulated in an effective part, and the burden on a driving circuit is thus reduced to realize high-speed operation. At the same time, when a clad on the carrier injection side, of clad layers formed on both sides of the waveguide, is a second clad layer, and a clad on the substrate side is a first clad layer, a third clad layer is formed on the first clad layer to reduce propagation loss in the waveguide.

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Musashino, Japan

Masayuki Suehiro