Abstract: A method and apparatus for determining a shortest path between a source node and a destination node in an optical network of nodes interconnected with optical transmission links is disclosed. A wavelength graph is used to represent an optical network as a set of electronic nodes and optical channel nodes corresponding to the network nodes with a set of internal links and optical channel links. The electronic node represents the electronic switching fabric that interconnects OEO equipment within a physical node. A single-source shortest path algorithm (e.g., Dijkstra's algorithm) is applied to the wavelength graph to determine a shortest path. The transformation of the network representation to include the electronic node greatly reduces the number of links in the wavelength graph and significantly increases the computational efficiency.

Abstract: Packets conveying data are received by a router via input ports which impose on them optical carrier waves whose wavelengths correspond to the ports. Respective time-delays are applied to the packets and they are broadcast to spatial selectors that transmit them to spectral selectors. Amplifiers are distributed over the paths of the packets and the paths are organized in such a manner as to limit the number of semiconductor optical switches in the selectors and to minimize noise and optical crosstalk affecting the packets.

Abstract: A routing control method in an optical packet switching network including a plurality of optical packet switches. Each optical packet switch has a plurality of output ports used for sending packets to other optical packet switches, respectively. The method particularly includes a step of, in a one optical packet switch, monitoring congestion conditions at its output ports, a step of, in the one optical packet switch, transferring packets to be stored in a one output port that is judged in the monitoring step as in congestion, to other output port that is judged in the monitoring step as not in congestion, a step of, from the one optical packet switch, sending the packets as reflection packets via the other output port to an other optical packet switch corresponding to the other output port, and a step of, from the other optical packet switch, returning the reflection packets to the one optical packet switch.

Abstract: This application proposes a solution that makes access to the Optical Link State (OLS) information more efficient for use by upper level applications. Applications are independent of underlying routing protocols. This solution applies to all Link State based IGP protocols with the extension to optical networks, including OSPF and IS-IS.

Abstract: In accordance with a dynamic and recursive method, the number of required ADMs for a given set of light-paths in an OWDM ring network can be minimized. In one formulation of the minimum ADM problem, the method aims to create as many circular segments among the set of light-paths in the OWDM ring network as possible, and to form as few non-circular segments as possible from the remaining light-paths such that the number of shared ADMs can be maximized. In one example, the method of the invention operates in two phases: in the first phase, a dynamic and recursive searching for all the possible circular segments among the light-paths is employed, after which the concatenated circular segments are removed from further processing. Next, a reverse recursive searching among the remaining light-paths for concatenated non-circular segments with as many light-paths as possible is conducted.

Abstract: An ultra-low latency optical router with a peta-bit-per-second total aggregate switching bandwidth, that will scale to a total connectivity of 1000 by 1000, and beyond by modular upgrades, that utilizes advanced optical technologies to achieve such high capacity with two to three orders of magnitude less volume and power requirements than the electrical router counter part, that serves as a universal engine to other optical routers being developed by vendors and researchers today, that can function in the context of circuit-switching, flow-switching, burst-switching, and packet-switching, that uses advanced wavelength conversion technology to effectively achieve three methods of contention resolution in the router: deflection in wavelength, deflection in space, and buffering in time, and that interfaces a local network to the Supernet.

Abstract: A system and method are disclosed for carrying additional information data on multiplexed signals which are modulated on different wavelengths. An information code such as an address or control data for a particular data signal at a selected wavelength is overlaid on the parallel multiplexed signals. The information code may be overlaid by attenuation or changing the amplitude of the different signals. A separate marker channel at a separate wavelength is also multiplexed with the data signals to indicate the presence of an information code. An optical data detector array is used to optically determine the encoded address by comparing the signals with light levels and producing an output when a matching code is detected. The optical data detector array uses a series of detectors each corresponding to the wavelength of light signals carrying the information data.

Abstract: A wavelength access server (WAS) architecture provides aggregation of traffic streams of diverse data communication protocols as well as provision of wavelength resources in an optical transport network. The WAS provides functions such as service traffic adaptation, traffic aggregation and segmentation, traffic classification, optical inter-working and system management. In particular, system management includes aspects such as signaling, connection management, resource co-ordination, protection prioritization and access policy management.

Abstract: An optical transmission apparatus implemented as an OADM (Optical Add/Drop Multiplexer) includes quality monitors each for monitoring the quality of a signal arriving on a particular optical transmission path. A monitor/control unit converts quality signals output from the quality monitors to path-by-path bit error rates, or estimation values, and compares them to select a route. The monitor/control unit then generates a metric value “1” for the route selected and adds it to one of identical metric values, which are assigned to routes to the same destination, that corresponds to the route selected. The monitor/control unit can therefore select a route closer to actual transmission path conditions. A method of determining an optimal route for optical transfer is also disclosed.

Abstract: An optical switch is equipped with a set of optical intensity controllers at its input, each intensity controller being driven to vary a corresponding WDM input traffic signal with a low power test signal. The switch is also equipped with optical splitters at its output and a path integrity analyzer connected to the splitters and to the intensity controllers. The path integrity analyzer generates or controls generation of the test signals applied by the intensity controllers. The path integrity analyzer also receives the tapped portions of the WDM output signals and separates them into their single-carrier components in order to recover a set of switched single-carrier optical signals. The path integrity analyzer is further provided with test signal detectors used to detect the presence of a test signal in each recovered switched single-carrier optical signal.

Abstract: The present invention is directed toward a distributed intelligence fiber-optic communication network in which node control processors (NCPs) associated with each network element periodically transmit identification and status information to the other NCPs in the network. Various faults in the network can thus be readily identified, and appropriate tasks for modifying the network in response to the fault (such as rerouting around a defective network element) can be carried out. Further, information continues to be distributed among the NCPs even if a break occurs in a segment of fiber in the network.

Abstract: A method and apparatus for a network database in an optical network. According to one embodiment of the invention, a wavelength division multiplexing optical network includes optical network devices interconnected by links. These optical network devices propagate along the links connectivity request messages, initiated at each of the optical network devices acting as an access node, to discover possible end to end paths that meet a set of zero or more connectivity constraints, where an end to end path is a series of two or more of the optical network devices connected by links on which a set of wavelengths is available for establishing a lightpath. In addition, the optical network devices acting as access nodes each include a database representing available paths with costs from that access node to reachable destination nodes, where each of the paths has associated with it in the database the wavelengths available on that path.

Abstract: A high speed optical communication and data transfer network comprises fiber optic links interconnecting a plurality of hybrid electronic-optical switch devices, each hybrid switch circuit including an electronic switch, electronic switch controller and optical switch. The hybrid switch circuits and nodes on the periphery of the core network communicate amongst each other over a first dedicated wavelength. Optical signals on the first dedicated wavelength are converted to electronic signals which are monitored by the electronic controller in each hybrid switch circuit. Routing in the network is optimized by transmitting lower volume data traffic on the first dedicated wavelength which is typically slower due to optical/electronic signal conversions and which uses more resources. Higher capacity data transfers are achieved by transmitting data on an assigned carrier wavelength over an established flow path among the optical switches of multiple hybrid switch circuits.

Abstract: In a system and method of optical communication, optical signals are generated in multiple wavelength channels. Each optical signal is passively transported from an origination node of a network to a destination node. The destination node is determined by the signal wavelength. For at least some signals, the passive transport includes transport through a branch point of the network, such that the signal wavelength determines the output branch through which the signal is routed. In certain embodiments, signals are generated according to a schedule devised to substantially prevent the concurrent arrival, at the same destination node, of signals having the same wavelength but coming from different origination nodes.

Abstract: A diversification route (Connection-B) is generated after establishing a first path (Connection-A) through the network (10) between an ingress client node (12) and an egress client node (14) through a first ingress network element (16) within the optical network. Information identifying the first network element is passed by the ingress client node (12) to a second network element (18) in the network. Information identifying the first path and desired diversity type is passed from the second network element (18) to the first network element (16). In response to receiving the information identifying the first path, an entity list associated with the first path is passed from the first network element (16) to the second network element (18). The second path (Connection-B) is established responsive to the information associated with the first path (Connection-A).

Abstract: An apparatus for wavelength assignment in wavelength multiplexing optical ring networks includes: a node section receiving a connection setup request, the node section comprising a plurality of nodes; and a wavelength assignment controller connected to the node section for, when the connection setup request occurs, determining paths available between the nodes using sparse wavelength conversion and limited wavelength conversion, calculating the total number of gaps for each node available, and assigning wavelengths to a path having the smallest total number of gaps. The present invention assigns wavelengths in consideration of both sparse wavelength conversion and limited wavelength conversion to minimize the call-blocking probability, and uses the wavelength in adjacent partitions to calculate the number of gaps for each wavelength and the total number of gaps.

Abstract: A system and method for minimizing blocking in optical networks utilizes algorithms developed to reduce non-revenue generating OEO conversions as a result of blocking based on routing and wavelength and/or subband assignment. Demands are prioritized on a basis of optical reach, and regenerators required for overcoming optical reach limitations are strategically placed to overcome blocking.

Abstract: The is directed to extending wavelength routing on a metro network subtended off an optical agile network. Flexibility on the subtended metro network is obtained by either tuning the head-end transmitter on a metro wavelength that is the operating wavelength of the route to a specified tail-end node (tunable source, fixed wavelength-route dependency) or/and tuning a specified route to the metro wavelength (fixed source, tunable wavelength-route dependency). The routes may be tuned at one or both ends.

Abstract: Disclosed is a novel method of allocating resources within an optical network in order to establish an optical path between a first node and a second node. A query signal, proposing a wavelength and timeslot pairing is sent to switching elements along a proposed optical path from the first node to the second node. The query signal is provided along with data indicating the availability of the switching elements along the proposed path. The query signal and data are used to determine an appropriate wavelength and timeslot pairing. When a wavelength and timeslot pairing has been chosen the appropriate switching elements are instructed to support the wavelength timeslot pairing along the optical path.

Abstract: An optical network is formed by a plurality of optical network transmission apparatuses and a plurality of transmission lines that connect the optical network transmission apparatuses. Each optical network transmission apparatus includes an advertisement unit which autonomously advertises a usable wavelength in a transmission line connected to the apparatus, and a collection unit which autonomously collects a usable wavelength in a transmission line that is advertised by another apparatus. An optical network transmission apparatus, a distributed routing control method used for the apparatus, and a recoding medium which records the program of the method are also disclosed.

Abstract: A wavelength router is provided that selectively directs spectral bands between an input port and a set of output ports. The router includes a free-space optical train disposed between the input port and the output ports. The free-space optical train may include air-spaced elements or may be of generally monolithic construction. The optical train includes a transmissive dispersive element, such as a transmissive diffraction grating, disposed so that light is intercepted from the input port and encounters the transmissive dispersive element at least four times before reaching any of the output ports.

Abstract: In a semiconductor device comprising photo-transceiver arrays constructed on silicon substrates with underlying supporting CMOS circuitry in the substrate interfacing with a source of software control, a method is provided for mapping and reconfiguring the global data transfer channel map of optical interconnect lines and intra-nodal routing links. An initial mapping procedure identifies all possible connections. The silicon circuitry provides for sensing optical connections and light levels, for testing or sensing of routing links, and for controlling gain and power, as well as forming and reforming routing links between detectors and emitters. A rule-based routing, mapping and re-mapping scheme, utilizing over-sampling techniques and effectuated by the silicon circuitry and software, accommodates limited misalignment of mating photo-arrays, faults occurring in data transmission channels after the initial mapping, and provides additional security, performance and power management capabilities.

Abstract: Disclosed is a WDM network which has: a lightwave path which connects between clients and each of which is provided with an overhead, and a sub-network which is defined by dividing the WDM network. In this WDM network, the sub-network has a partial lightwave path to go through the sub-network, the overhead has a partial lightwave path supervisory control information region which is terminated at both nodes of the partial lightwave path, and when a fault occurs on a lightwave path, the fault information of partial lightwave path including the position information of fault occurred is added to the partial lightwave path supervisory control information region of the overhead.

Abstract: A monitoring apparatus and method are provided for a communication system in which a central office communicates to at least one end unit using intermediate remote nodes. The remote node receives signals from both the central office and the end units. Each remote node can be equipped with apparatus for monitoring the integrity of paths of the communication system. The monitoring apparatus can include a mixing device that mixes received signals to produce combined signals. The received signals generally include a pilot signal sent from the central office and a data signal sent from the at least one end unit. The state of the communication system is analyzed based on the combined signals. If the combined signals includes only the data signal from the end unit, the path through which the pilot signal was sent is inoperative. If the combined signals includes only the pilot signal, the transmission path from the end unit over which the data signal is sent is inoperative.

Abstract: An optical communication equipment comprises shared optical sources 88a-88d to be shared by communication nodes 100a-100d, the wavelengths of optical signals 76a-76d are converted into desired wavelengths &lgr;a-&lgr;d according to the addressed information of the corresponding optical label signals 77a-77d by using the shared optical sources 88a-88d and routed to the addressed communication nodes without being converted into electrical signals by using the wavelength routing function of the cyclic-wavelength arrayed-waveguide grating (AWG) 120. The load of each communication node can be reduced by incorporating the multi-wavelength optical sources, which can be shared among individual communication nodes, into the router 80.

Abstract: A four fiber ring network optical switching circuit capable of realizing the bridge function at times of the span switching and the ring switching economically by a very compact structure is disclosed. A four fiber ring network optical switching circuit is formed by a 10×8 optical matrix switch having ten input ports and eight output ports, and two branching elements adapted to branch each one of two optical signals among eight optical signals that are inputs of the four fiber ring network optical switching circuit, into two identical optical signals, and to enter the two identical optical signals into two input ports of the 10×8 optical matrix switch such that the eight optical signals are entered into the ten input ports of the 10×8 optical matrix switch as ten optical signals.

Abstract: An optical router integrated in an InP-based substrate bonded to a single thermo-electric cooler for packet-based networks utilizing wavelength-division multiplexing (WDM) on silica fibers. Input and output arrayed waveguide gratings (AWGs) respectively demultiplex and multiplex the WDM signals to and from multiple transmission fibers. Input and output wavelength converters are connected between the input and outputs AWGs and a switching AWG. The output converts may include a tunable laser and interferometer formed in the same substrate. The header information is preferably carried out-of-channel from the WDM data signals, either in the same fiber band or a different one. Photodetectors and laser diodes are formed in the same substrate.

Abstract: The present invention is directed to an optical space switch accommodating a plurality of input light paths and output light paths. The optical space switch comprises a plurality of polarization control optical switches, each consisting essentially of: polarization control means having elements, one for each input light path, for rotating through 90° the polarizing direction of light information incident from each input light path or otherwise retaining the polarizing direction thereof for output; and a light path routing element for routing the light path for the light information output from the polarization control means in accordance with the polarizing direction of the light information. These polarization control optical switches are arranged in a matrix pattern or coupled in cascade to implement a polarization control optical space switch.

Abstract: An optical communication equipment comprises shared optical sources 88a-88d to be shared by communication nodes 100a-100d, the wavelengths of optical signals 76a-76d are converted into desired wavelengths &lgr;a-&lgr;d according to the addressed information of the corresponding optical label signals 77a-77d by using the shared optical sources 88a-88d, and routed to the addressed communication nodes without being converted into electrical signals by using the wavelength routing function of the cyclic-wavelength arrayed-waveguide grating (AWG) 120. The load of each communication node can be reduced by incorporating the multi-wavelength optical sources, which can be shared among individual communication nodes, into the router 80.

Abstract: The invention concerns an optical routing device for coupling each of a plurality NE of optical incoming channels (1) to one of a plurality NS of optical output channels (5) and for orienting each of the optical beams coming through the incoming channels to any one of the NS optical output channels, comprising: an input module (40) including NE optical inputs, designed to shape each one of the beams coming through the optical incoming channels, so as to obtain a plurality of shaped optical beams (112); an input deflection module (30) designed to generate for each of the inputs a number PTN of different positions of angular deflection at least equal to the number NS of optical output channels; a linking module (50) designed to assemble in bi-unique manner on PTN spatial focusing points, respectively the PTN angular deflection positions of each of the inputs, said module being designed to generate PTN intermediate optical beams; an output deflection module (35) having PTN inputs designed to intercept PTN interm

Abstract: A modular optical router/switch construction system and method are described. In one aspect of the present invention, the modules provided are basic 1×N optical components and/or pass-through 1×N optical components, both of which have input/output (I/O) ports which are capable of detachably interconnecting. Pass-through 1×N optical components are like the basic 1×N optical components but include extra ports so that input light may “pass through” the component. In another aspect of the present invention, a bi-directional optical component capable of modular construction is provided. The bi-directional optical component has the same I/O ports as the basic 1×N optical component, but the bi-directional I/O ports are built to engage a duplex optical link (i.e., a link comprised of two optical fibers with signals going in two opposite directions).

Abstract: The present invention provides a fast rerouting method through Generalized Multi-Protocol Label Switching (GMPLS). The method performs fast rerouting through when a failure occurs on a link and node in an optical network having a plurality of nodes. In the fast rerouting method, current node of the optical network receives the path message for label request from a higher node thereof and establish the main LSP. Further, the current node calculates a detour path therefrom to a next but one node thereof so as to provide against a failure of the next node. Further, if it is checked that the Loss Of Light (LOL) occurs in the current node, the current node establishes the detour path to allow data to flow through the calculated detour path.

Abstract: A system and method is disclosed for providing high-speed, high capacity data communication over a Wave Division Multiplexing (WDM) network with an efficient re-routing capability. When all light channels between two nodes in the network are loaded with transmission jobs, a transmission traffic congestion is created. In order to avoid or alleviate the congestion, a new alternative route is needed. An alternative route is selected to direct the traffic away from the congested route, and further expand the channel capacity of the alternative route by encoding the light channels in the alternative route with orthogonal codes.

Abstract: An optical network, which may be an all-optical network, including passive wavelength routers is described. Methods for implementing such networks as well as different router configurations which may be used in optical networks are also disclosed. The routing functionality in the all-optical network can be done in the optical domain without switching elements at the nodes. This is achieved by routers which are passive and preferably operative to route wavelength bands. A mesh can be used as the network configuration. The optical networks described can be used to facilitate the transmission of higher network protocols, such as internet protocol (IP) packets or ATM-cells, purely in the optical domain.

Abstract: A method and apparatus for control and data burst routing in WDM photonic burst-switched network is disclosed. In one embodiment, only the control bursts and network management labels are going through optical-electrical-optical conversion inside the photonic burst switching (PBS) module. The building blocks of the control processing unit inside the PBS module may include input and output buffers, control burst parser, burst scheduler, PBS configuration and control, contention resolution, forwarding engine, network management controller, control burst generator, and queue manager. The contention resolution block may be used to resolve resource contention between multiple data bursts. Such contention resolution may take the form of adding additional delays to one of the data bursts, changing one of the data bursts to an alternate wavelength, or dropping some of the data bursts based on various criteria such as relative priority and wavelength.

Abstract: A high speed optical communication and data transfer network comprises fiber optic links interconnecting a plurality of hybrid electronic-optical switch devices, each hybrid switch circuit including an electronic switch, electronic switch controller and optical switch. The hybrid switch circuits and nodes on the periphery of the core network communicate amongst each other over a first dedicated wavelength. Optical signals on the first dedicated wavelength are converted to electronic signals which are monitored by the electronic controller in each hybrid switch circuit. Routing in the network is optimized by transmitting lower volume data traffic on the first dedicated wavelength which is typically slower due to optical/electronic signal conversions and which uses more resources. Higher capacity data transfers are achieved by transmitting data on an assigned carrier wavelength over an established flow path among the optical switches of multiple hybrid switch circuits.

Abstract: A modular optical switch includes a set of optical switch modules connected in a mesh, a master controller for the whole optical node and a switch-module controller for each of the optical switch modules. The optical switch modules receive optical signals from, and transmit optical signals to, edge nodes based on connection requests received from the edge nodes. The master controller acts to select a path, using a simple or compound time-slot matching process, through the mesh of switch modules for each optical signal related to a connection request. Advantageously, the optical switch modules are fast switching, enabling the use of time-sharing schemes such as TDM, and the modular optical core node is made practical by efficient path selection at the master controller. A hybrid modular switch may include both optical and electronic switch modules, a master controller, and a switch-module controller for each of the switch modules.

Abstract: A lightpath segmentation system and method for use in a GMPLS network is described. In one embodiment, lightpaths are divided into segments according to the distribution of the wavelength-converter-equipped optical switches, or nodes, within a WDM network. As the number of hops within the segment increases, a lightpath segmentation probability increases. When a wavelength-converter-equipped node receives an LSP Request message, it calculates the LPSP and, if the LPSP exceeds a threshold, the node sets up a lightpath between itself and the ingress node or a previous upstream wavelength-converter-equipped node, if the lightpath has already been segmented.

Abstract: The device, which has a modular structure, makes use of Bragg gratings for selecting, from a wavelength division multiplexed stream, a carrier to be inserted or extracted, and optical circulators for receiving the stream, for extracting and inserting the carriers and for sending the multiplexed stream to the output after the extraction and insertion of the carriers. The grating and the receiving-extracting circulator are located in a structural module which is replicated for all the channels to be extracted and inserted.

Abstract: 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.

Abstract: An optical communication network is provided for reducing a required number of transmitters and receivers. A management device gives the amount of traffic passing through optical cross-connect devices along a route as an evaluation value for the route (step S6), and selects the route which has the largest evaluation value (step S7). The management device determines whether or not the evaluation value given to the selected candidate route is larger than a predefined reference value (step S8). When larger than the reference value, the management device outputs the route as an optical transmission path which includes at least one or more optical add-drop multiplexers (step S9).