Nippon Telegraph and Telephone Corporation

Wataru Imajuku

Yutaka Miyamoto

Eiji Oki

Akira Hirano

Takuya Oda

Hidehiko Takara

Takafumi Tanaka

Tetsuro Inui

Shoukei Kobayashi

Naoaki Yamanaka

Kohei Shiomoto

Yoshitada Katagiri

Atsushi Takada

Kunihiko Mori

Yoshihiro Takikawa

Satoru Okamoto

Nobuaki Matsuura

Etsu Hashimoto

Masaru Katayama

Daisaku Shimazaki

Kentaro Uchiyama

Katsuhiro Shimano

Naohide Nagatsu

Yasutaka Okazaki

An optical amplification system includes: three or more nodes; a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of the connection between the nodes; an amplification light input unit configured to input amplification light to a core of the plurality of cores of the multi-core fiber; an amplification unit configured to amplify communication light transmitted through at least one core of the plurality of cores of the multi-core fiber using the amplification light, the amplification unit being provided in the nodes or between the nodes; and an amplification light coupling unit configured to couple the amplification light input by the amplification light input unit to the amplification unit.

Optical amplification system and optical amplification method

A transmission quality estimation system includes, three or more nodes and a transmission quality estimation device configured to estimate, transmission quality. A multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of a connection between the nodes. A node of the nodes includes a core connection unit configured to drop, add or relay light transmitted from, to or to each of to the plurality of cores of the multi-core fiber. The transmission quality estimation device includes an estimation unit configured to estimate transmission quality between the nodes on the basis of a transmission quality measurement light dropped by the core connection unit.

Transmission quality estimation system, transmission quality estimation device, and transmission quality estimation method

A communication system which includes: three or more nodes; a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of a connection between the nodes; a detection signal output unit configured to output a fault detection signal transmitted by the core provided in the multi-core fiber configured to connect together the nodes; and a fault detection unit configured to determine whether a fault has occurred between the nodes on the basis of a detection result of the fault detection signal.

Communication system and fault detection method

A communication system includes three or more nodes and a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of the connection between the nodes is provided. One node of the nodes is connected to the multi-core fiber and includes a connector configured to add and drop a signal to and from an allocated core exclusively allocated from among the cores as a communication path between the one node and another node of the nodes and/or configured to relay a signal transmitted through another core of the cores allocated for communication between other nodes in the multi-core fiber connected to the one node, and a relative positional relationship between a connection position of the allocated core in which a signal is added or dropped in the connector and a connection position of another core in which a signal is relayed in the connector is the same for all of the nodes connected to the multi-core fiber.

Communication system and connector

A communication system includes three or more nodes, and a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of a connection between the nodes, wherein each of nodes includes: a fault information transmitting device configured to transmit fault information indicating that a fault has occurred in a communication path between one node and another node of the nodes when it is detected that it is not possible to perform communication between the one node and the another node; and a fault location specifying device configured to specify a section between nodes in which a fault has occurred on the basis of the fault information received from the fault information transmitting device provided in each of the nodes.

Communication system and fault location specifying method

In a disclosed backup path bandwidth keeping method for keeping bandwidth of a backup path to which an active path is switched when the active path becomes unavailable in nodes of a communication network, each node is connected to the same destination, and the method includes a backup path bandwidth keeping phase, for M (M is a natural number equal to or less than L) channels in L (L is a natural number) channels kept as backup path bandwidth, for notifying a destination-side node existing in a destination side of the backup path of identification number information of the M channels to be kept and identification information indicating that a path for which the bandwidth is to be kept is a backup path.

Device and method for correcting a path trouble in a communication network

An upper layer node is used in a multi-layer network which includes an upper layer network which performs switching and transfer in units of packets, and a lower layer network which includes optical transmission lines and optical switches and accommodate the upper layer network; this upper layer node being connected to the lower layer network which includes lower layer nodes including obstruction restoration sections, and transmission lines, and including: a section which detects the occurrence of an obstruction upon a transmission line which it accommodates; a section which advertises the detection result as obstruction information; a section which retains the topology information for the network; a section which updates the retained topology information according to advertised obstruction information, or obstruction information which it has detected; and an advertisement transfer section which advertises to other upper layer nodes the advertised obstruction information.

Upper layer node, lower layer node, and node control method

A multi-layer photonic network and nodes used therein are provided. The multi-layer photonic network comprises a packet network which performs switching and transfer in packet units, and a photonic network comprising optical transmission lines and photonic switches, and which accommodates the packet network. The multi-layer photonic network also has a two layer structure of optical wavelength links (O-LSPs) and packet links (E-LSPs). The O-LSPs are constituted by the optical transmission lines and comprise optical wavelength switching capability (LSC) which is capable of switching in optical wavelength units and packet switching capability (PSC) which is capable of switching in packet units at both their ends. The E-LSPs include the O-LSPs and PSCs at both their ends. Each node includes a section for automatically establishing an O-LSP according to an establishment request for an E-LSP while taking account of path information including path cost, resource consumption, and traffic quantity.

Node used in photonic network, and photonic network

The invention relates to a node, an optical/electrical path integrated network using this node, and a program which controls the node. The node according to the invention is suited to use in an optical/electrical path integrated network constructed from a plurality of electrical sub-networks comprising nodes which are interconnected by electrical paths in which routing is performed based on packet header information and a photonic core network comprising nodes which are interconnected by optical paths, the photonic core network and the plurality of electrical sub-networks being interconnected by optical paths, wherein the node comprises a device which outputs to other nodes, a traffic quantity between the node to which it belongs and other nodes.

Node, an optical/electrical path integrated network using the node, and a program which controls the node

A source node, along with transmitting an optical path setup request, notifies towards a destination node available resource information related to itself, pre-assigns the available resources which its own node has notified. Each of transit nodes, along with relaying towards the destination node the optical path setup request which has been received from a previous hop node, notifies towards the destination node available resource information related to itself, and pre-assigns the available resources which each of their own nodes has notified. The destination node, along with reserving a resource which is to be used for setting up an optical path based upon an optical path setup request which has been received, transmits a resource reservation request towards the source node. The transit nodes and the source node actually reserve an available resource which has been pre-assigned, based upon a resource reservation request from a next hop node.

Optical path communication network, node, and optical path setup method

Optical wavelength control method and apparatus which are capable of controlling an optical wavelength of a light source with a central wavelength which is uncertain and unstable at nanometer order is disclosed. In the optical wavelength control apparatus, the control target light entered from the variable wavelength light source is scanned at a prescribed period and optical pulses having a phase corresponding to the optical wavelength of the control target light are obtained. Then, a phase difference between a phase of the optical pulses and a phase corresponding to a reference optical wavelength is detected, and the variable wavelength light source is controlled by feeding back the phase difference to the variable wavelength light source such that the optical wavelength of the control target light is controlled by an optical frequency pulling with respect to the reference optical wavelength according to the phase difference.

Method and system for controlling optical wavelength based on optical frequency pulling

An optical parametric circuit including an optical coupler including a first output port and a second output port, and a nonlinear loop mirror on which an optical path which connects the first output port and the second output port is formed, in which the nonlinear loop mirror includes an optical dispersive medium and a second-order optical nonlinear medium through which the optical path passes, and in which an order of placement of the optical dispersive medium and the second-order optical nonlinear medium on the optical path in one direction from the first output port to the second output port is the reverse of an order of placement of the optical dispersive medium and the second-order optical nonlinear medium on the optical path in another direction from the second output port to the first output port.

Optical parametric circuit

Method and apparatus for controlling optical wavelength based on optical frequency pulling

An optical parametric circuit for separating an input signal light and a wavelength-converted light even when the wavelength difference is small is provided. The optical parametric circuit includes: a nonlinear Mach-Zehnder interferometer which includes a first optical path and a second optical path; optical dispersive mediums and second-order optical nonlinear mediums provided in the first and second optical paths; wherein optical dispersive medium and second-order optical nonlinear medium in the first optical path are placed in the reverse order of optical dispersive medium and second-order optical nonlinear medium in the second optical path.

A phase-lock loop is formed by a voltage-controlled oscillator, a local optical pulse source, an optical branching device for branching the locally generated optical pulse stream from the local optical pulse source, a harmonic component local generation part for locally generating a harmonic component electrical signal from the one of two branched locally generated optical pulse streams, and a phase comparison part for comparing the phases of the locally generated harmonic component electrical signal and an incoming signal component electrical signal generated from an incoming optical signal pulse stream and for supplying the voltage-controlled oscillator with a control voltage corresponding to the phase difference between the two input electrical signals. The other branched output from the optical branching device is output as a locally generated optical pulse stream bit-phase synchronized with the incoming optical signal pulse stream.

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Yokohama, Japan

Wataru Imajuku