Abstract: A ring connection system and method are provided for distributing signals in an optical-to-electrical interface. The method electrically connects a plurality of nodes in a series-connected ring, and receives an optical signal at a first node from a service provider. The method converts the optical signal to an electrical signal, and distributes the electrical signal via the ring. At each node, the electrical signal is supplied from a customer interface. Typically, each node has a plurality of customer interfaces. In one aspect, ITU-T G.984.3 Giagbit-capable Passive Optical Network (GPON) optical signals are received converted to a customer interface electrical signal such as an Ethernet, asynchronous transfer mode, or time division multiplexed signal. Electrically connecting the plurality of nodes in the series-connected ring includes: series connecting the nodes in a North ring; and, series connecting the nodes in a South ring, opposite in direction from the North ring.

Abstract: A radio base station for a mobile radio network, includes a set of remote units connected with the radio base station, preferably via a radio over fibre arrangement. Each remote unit provides radio cell coverage by means of a set of communication channels, and is equipped with a respective set of antenna elements. The communication channels are distributed over the antenna elements according to an assignment scheme that is dynamically variable.

Abstract: A method and system for ensuring confidentiality of signal transmission in a point-to-multi point data transmission network like Ether net passive optical network, including at least one hub, at least one transmission medium and at least one station connected to the hub via the transmission medium. When an upstream signal is transmitted from a first station, the upstream signal is reflected by at least one disturbing reflector for producing a disturbing reflection. The disturbing reflection combines with a second reflection of the upstream signal and renders the second reflection undependable by a second station.

Abstract: A ringed optical transmission system comprises along the ring rare earth doped fiber amplifiers. The system has a gain peak with a ?ASE wavelength outside the ?1-?n band of the channels transmitted along the ring, the wavelength corresponding to an ASE emission peak of the amplifiers in the ring. In this manner a lasing peak forming a gain stabilization signal is produced.

Abstract: A method of automatically generating a computer based layout of an optical communication network is provided. First, communications traffic demand forecast data for an optical communication network is received. Network data corresponding to a deployed optical communication network is also received. Thereafter, a network plan can be automatically generated. The network plan corresponds to a modified network that may be deployed. Also, the network plan can be derived from the network data. Further, the network plan can be constructed in response to the performance of a grooming operation that includes a first level of grooming at an optical level of the modified network and a second level of grooming at an electrical level of the modified network.

Abstract: An optical wireless local area network using line of sight optical links. The base station and terminal stations are provided with optical transceivers which include a transmitter array and detector array. The transmitter array consists of an array of resonant cavity light emitting diodes integrated using flip-chip technology with a CMOS driver circuit. The driver circuit includes constant bias, current peaking and charge extraction. The driver circuitry is compact and can be confined within a region underlying the corresponding light source. The detector array consists of an array of photo diodes, provided with sense circuitry consisting of a pre-amplifier and post-amplifier. The diodes and sense circuitry are also integrated using a flip-chip technique. The light emitter and the detector may include adaptive optical elements to steer and/or focus the light beams.

Abstract: A method for designing a communication network is provided. First, network demand data is gathered. Network architecture data is also gathered. Based in part on the network demand data and the network architecture data, a network plan is automatically generated.

Abstract: A single, normally inactive, protection channel provides protection against transponder failure in a fiber optic ring network. The protection channel is established and put into operation by a series of steps that are triggered by the detection of loss of light from one transponder by the other transponder. Each node reacts to a loss of light from another node in the same way: by rerouting incoming traffic from external sources from a working input-output interface to a protection interface, to establish a path for the protection signal, and by sending a signal enabling the two nodes to resume communication.

Abstract: A ring connection system and method are providing for distributing signals in an optical-to-electrical interface. The method electrically connects a plurality of nodes in a series-connecting ring, and receives an optical signal at a first node from a service provider. The method converts the optical signal to an electrical signal, and distributes the electrical signal via the ring. At each node, the electrical signal is supplied from a customer interface. Typically, each node has a plurality of customer interfaces. In one aspect, ITU-T G.984.3 Giagbit-capable Passive Optical Network (GPON) optical signals are received converted to a customer interface electrical signal such as an Ethernet connecting transfer mode, or time division multiplexed signal. Electrically connecting the plurality of nodes in the series-connected ring includes: series connecting the nodes in a North ring; and, series connecting the nodes in a South ring, opposite in direction from the North ring.

Abstract: An enhanced Dense Wave Division Multiplexing (DWDM) network is optimized through bundling subchannel traffic in DWDM channels at network nodes and “hubbing” the DWDM channels at nodes receiving a relatively higher volume of aggregate traffic than other nodes. The optimization can eliminate low rate links and supporting network equipment. The bundling and hubbing may also be used independently from one another. The DWDM network may be enhanced with SONET, SDH, Ethernet, ATM, or other technology. The DWDM network may be a BLSR, UPSR, point-to-point, mesh, or other network configuration.

Abstract: An apparatus achieves data communications between a data storage controller and data storage devices within a data storage system via an optical network. The apparatus includes a wavelength division multiplexing logic for simultaneously establishing, on the optical network, a number of arbitrated communications loops between the controller and the data storage system, for communicating data between the controller and the storage devices.

Abstract: An optical network for providing a plurality of end users with video content, which includes a plurality of video head ends, each coupled to a pair of video hub offices via a plurality of diverse optical communication paths, where each hub office is coupled to a plurality of video serving offices via a pair of optical fibers arranged in a ring structure to provide a working link and a protection link, each video serving office adapted and arranged for distributing video content to a plurality of end users.

Abstract: A communications system connects one or more BTS hotels with several remote access nodes on a transmission ring. Each operator has one or more separate optical wavelengths. Signal flow around the ring can either be uni-directional or bi-directional. Each optical wavelength (or wavelength pair) contains the wireless signal traffic for all remote nodes in the ring for the operator using that particular wavelength in digital form. At each node, the incoming signals are electrically demultiplexed and appropriate signals for that node are extracted for conversion to RF. These signals are copied rather than cut so that they are also available at following remote antenna nodes, thereby enabling simulcast operation.

Abstract: A relay transmission apparatus in which the effectiveness of a protecting function is improved by suppressing variation of an OSNR value of a signal regardless of the distance that the signal is transmitted. The relay transmission apparatus is comprised of a first regenerative relay unit, a second regenerative relay unit, and a protection process unit for extracting a signal component from each of the first and second regenerative relay units and selectively outputting either of the extracted signal components as a drop signal.

Abstract: A system and method for a transparent WDM metro ring architecture in which optics enables simultaneous provisioning of dedicated wavelengths for high-end user terminals, while low-end user terminals share wavelengths on “virtual rings”. All wavelengths are sourced by the network and remotely modulated at customer “End Stations” by low cost semiconductor optical amplifiers, which also serve as transmission amplifiers. The transparent WDM metro ring architecture permits the communication of information and comprises a fiber optical feeder ring, at least one fiber optical distribution ring, a network node (NN), at least one access node (AN) said network node and said at least one access node connected via said fiber optical feeder ring and at least one end station (ES) connected via said fiber optical distribution ring to said at least one access node, wherein said user is attached to said at least one end station.

Abstract: An optical device includes: a substrate side waveguide formed on a substrate; and a plurality of optical elements fixed on the substrate. The substrate side waveguide and an optical element side waveguide formed in each of the plurality of optical elements forms a continuous optical waveguide path.

Abstract: A network includes multiple nodes interconnected to form a ring topology. These nodes support data transmissions over the network using tokens. To send and receive data over the network, nodes may process control messages. A node can receive a first token authorizing transmission on one of multiple data channels, generate a transmission control message identifying a destination node and the authorized data channel, and communicate the transmission control message to a next node. The node can also communicate a second token to the next node authorizing secondary transmissions on the authorized data channel, transmit data on the authorized data channel after communicating the transmission control message, and communicate the first token to the next node after communicating the second token to the next node.

Abstract: An optical communication system is constructed which enables highly reliable and flexible connection to communication nodes connected to a path establishment circuit, by utilizing wavelength-routing characteristics of a path establishment circuit such as an arrayed waveguide grating. The optical communication system has multiple communication nodes having a signal output port and signal input port pair, and a path establishment circuit having multiple optical input ports and multiple optical output ports which are set so that optical signals input from the respective optical input ports are output to predetermined optical output ports corresponding to the wavelengths of the optical signals.

Abstract: A symmetrical capacity network may be adapted to accommodate asymmetrical network traffic patterns by deploying Protected Dedicated Wavelengths (PDWs) between one or more head-end nodes and the access nodes on a ring-based topology network. The PDWs include pairs of wavelengths extending in opposite directions around the fibers forming the original ring and terminating at the intended access node. The pairs of wavelengths form unidirectional working and protection paths from the head-end node to the intended access nodes. By deploying the symmetric capacity and asymmetric capacity on the same platform within the head-end node, it is possible to apply policy across the network resources to allow traffic flows to be selectively placed on the most appropriate network resource.

Abstract: A fiber optic network transmits data between a hub node and a plurality of local nodes connected by at least one unidirectional fiber ring. Downstream data streams are carried on wavelength-division-multiplexed optical carriers from the hub node to the local nodes. An optical carrier corresponding to a specific wavelength carries downstream data streams to a specific local node. Downstream data streams are multiplexed onto an optical carrier via orthogonal frequency division multiplexing. A parallel signal detector in each local node detects all downstream optical carriers. A signal processing module demultiplexes the data stream from the optical carrier having the specific wavelength corresponding to the local node. An upstream data stream is multiplexed via orthogonal frequency division multiplexing onto an upstream optical carrier having the same specific wavelength and transmitted from the local node to the hub node. Upstream data awaiting transmission is allocated to specific subcarriers and time slots.

Abstract: A wavelength division multiplex (WDM) optical network comprises a ring configuration of optical fiber links connecting a plurality of nodes and add and drop filters at each node connected in series within the ring. One or more of the filters are arranged to add or drop at least two selected adjacent wavelength channels of the WDM optical signal while allowing the remainder of the channels within the WDM signal to pass substantially unattenuated. The wavelength channels of each node are selected such as to maximize the number of adjacent wavelength channels at each node.

Abstract: An optical network system capable of directly routing optical signals without entailing multiple reception of identical wavelengths. A set wavelength output unit outputs a set wavelength. An Nk-axis filter receives an Nk-axis signal propagated through a ring of an Nk-axis direction and an Nk?1-axis signal split inside the local node, and performs filtering by removing a wavelength identical with that of the Nk?1-axis signal from the Nk-axis signal and adding the wavelength of the Nk?1-axis signal to the Nk-axis signal. An Nk-axis splitter splits the Nk-axis signal into two, one being output to outside through the ring of the Nk-axis direction while the other being output, if k<n, to a confluence with an Nk+1-axis signal, and, if k=n, to a wavelength separation filter. The filter separates a desired wavelength from the Nk-axis signal. Optical transmission media connect nodes so as to constitute an n-dimensional torus network.

Abstract: Methods and apparatus for enabling a protection path within a network to be monitored are disclosed. According to one aspect of the present invention, a method for sending traffic on a path within an optical network system that has a plurality of nodes and a plurality of fibers includes identifying a circuit path within the optical network system which is associated with a first node and includes at least one fiber. The method also includes sending a signal that includes embedded path trace information on the circuit path from the first node on the fiber, and determining when the signal is received from the first node by a second node over the fiber. Finally, the method includes broadcasting path trace information to the plurality of nodes when it is determined that the signal is not received by the second node over the fiber.

Abstract: A method and apparatus for providing a load balanced circuit path between a source node and a destination node within a SONET ring comprising a plurality of nodes and connected by links by iteratively selecting facilities within a link that have bandwidth utilization levels that are below a threshold level. In an alternative embodiment, an alternate path is selected in case facilities meeting the threshold level can not be found. The threshold level is changed incrementally if facilities and links within the first path and/or alternate path do not meet the threshold levels.

Abstract: A method, system and computer program for simulating a communication link, such as an uplink, to one or more external networks in a communication network is provided. A test optical network terminal is connected to the network, and an uplink is simulated through the test optical network terminal, providing access to one or more external networks to one or more network elements in the communication network. Traffic is looped through an optical line terminal using optical carrier cards, and virtual cross connects are provisioned in the communication network to create a communication path between the optical network terminal and the test optical network terminal. A method of troubleshooting a network element such as an optical network terminal is also provided.

Abstract: A system and method provide transparent LAN services in a metro-WAN environment to extend enterprise LANs over metro and wide area networks. The transparent LAN services generally provide customers with a layer two Ethernet connectivity with MAC learning capabilities.

Abstract: An all optical network for optical signal traffic provides at least a first ring with at least a first clockwise fiber, a second counter-clockwise fiber and a plurality of network nodes. Each node has at least a WDM transponder that with a line-side transmitter and a client-side receiver in a first direction, and a line-side receiver and a client-side transmitter in an opposing second direction. The line-side receiver includes a fixed or a tunable optical wavelength filter. At least a first add and a first drop broadband couplers are positioned on each fiber. Each coupler has first and second ports for through traffic and a third port for adding or dropping local traffic. The first add and first drop broadband couplers are configured to minimize a pass-through loss in each fiber. If there are multiple WDM transponders, their wavelengths are added to the ring either in series or in parallel. All wavelengths dropped from the ring are selected by each individual WDM transponder in a parallel or serial manner.

Abstract: A method for communicating optical traffic includes adding optical traffic to an optical ring comprising a plurality of nodes and communicating the optical traffic on the optical ring. The optical traffic comprises a plurality of virtual wavebands which comprise a first virtual waveband of traffic comprising a first number of wavelengths and a second virtual waveband of traffic comprising a second number of wavelengths. The second number is different from the first number. The method also includes dropping the first virtual waveband of traffic at a first node of the plurality of nodes and dropping the second virtual waveband of traffic at a second node of the plurality of nodes.

Abstract: When an optical path arrangement is re-arranged, the packet loss amount is reduced by judging whether to perform the shift in one stage or whether to perform the shift in two stages in accordance with the state of the network. This is implemented by an optical communication network comprising a plurality of routers, a plurality of optical switches, optical fiber connecting the routers and optical switches or connecting the optical switches, and a management device. First, the first evaluation value is determined by evaluating the packet loss amount resulting from a one-stage shift. Thereafter, when the optical path arrangement is changed by means of a two-stage shift, the optical path group to be changed is divided into two, one optical path group is selected as the first-order shift optical path, and the other optical path group is made the second shift optical path.

Abstract: Techniques, apparatus and systems for optical communications, including fiber ring networks with protection switching to maintain optical communications when an optical failure occurs and to automatically revert to normal operation when the optical failure is corrected, fiber ring networks that provide a circulating optical probe signal at an optical probe wavelength within the gain spectral range of optical amplifiers used in a fiber ring network to detect an optical failure, and fiber ring networks that support broadcast-and-select optical WDM signals carrying communication traffic to the optical ring nodes without regeneration at each optical ring node and one or more overlaid in-band node-to-node optical signals carrying communication traffic with regeneration at each node.

Abstract: An optical network includes an optical ring, a plurality of local nodes, and a data center node. The plurality of local nodes are coupled to the optical ring and each local node is capable of receiving traffic from a local client and associating a transmitter tag with the traffic. The transmitter tag identifies a virtual network of the local client. The local node is further capable of transmitting the traffic on the optical ring. The data center node is also coupled to the optical ring and is capable of receiving traffic transmitted by one of the local nodes and determining a receiver tag for the traffic, based on the transmitter tag associated with the traffic and the local node that transmitted the traffic. The data center node is also capable of associating the selected receiver tag with the traffic and transmitting the traffic on the optical ring.

Abstract: In a passive optical network system in which communication signals from a master station to a plurality of subsidiary stations are multiplexed by time division and transmitted, after converting (modulating) data with a high transmission speed to a low transmission speed, a base speed, in the master station, a header including an identifier destined for each subsidiary station is attached to the data with a low transmission speed and the converted data, respectively, the data and the header being multiplexed by time division inside a frame and transmitted to the subsidiary stations at the base speed. In the subsidiary station having received the concerned frame, only the data destined for the station itself is read, on the basis of the identifier included in the header, and by means of demodulation, the converted data are reconverted to the original high speed data and supplied to a user terminal.

Abstract: An optical access network system can be used to upgrade legacy passive optical networks by subdividing currently used optical bands (e.g., C-, S-, or O-bands) into subbands to support more wavelengths. The subbands can be used to provide various current or emerging services to end users. Optical transmitters may selectively transmit modulated/unmodulated optical signals in multiple subbands downstream. Demultiplexers demultiplex the optical signals into respective bands and subbands for delivery to multiple respective destinations. Optical transceivers may receive and modulate downstream, unmodulated, optical signals (e.g., in the optical O-band) and transmit the modulated optical signals upstream. Upgrades to legacy systems or future systems can be implemented in a cost effective manner with negligible, if any, disruptions in service noticed by the end user.

Abstract: A computer-based monitoring system provides interactive topology information about a synchronized optical network (SONET). The monitoring system utilizes a trunks integrated record keeping system (TIRKS) connected to the SONET for collecting status data in a raw format. A computer system retrieves the raw format status data from TIRKS and provides the data in a simple graphical user interface to a user. The interface includes several menus from which the user may specify specific components of the SONET, and a graphical output for providing a graphical representation of the SONET. The graphical output illustrates each node and link and interactively provides more detailed information about any user selected link or node.

Abstract: Provided is a multi-ring network operating method of cross-connecting at least two ring networks, the method including connecting an input working ring and an input protection ring of a ring network to an output working ring and an output protection ring of another ring network and then performing cross-connection between the same or different ring networks by using a multi-dimensional cross-connect apparatus. In the multi-ring operating method, a plurality of ring networks can be connected regardless of the protection method used by the ring networks, and the original protection method of each ring network can remain after they are connected.

Abstract: An optical network is operable to carry optical traffic in a plurality of wavelengths between a plurality of nodes. The optical network includes a light-trail, a convener node, one or more intervening nodes, and an end node. The light-trail is established in the optical network between the convener node and the end node and couples the convener node, the intervening nodes, and the end node. Furthermore, the light-trail is associated with one of a plurality of wavelengths. The convener node and the intervening nodes are each operable to determine whether another node having a higher priority is transmitting optical traffic on the light-trail and, in response to determining that no node having a higher priority is transmitting on the light-trail, transmit optical traffic to one of the nodes in the light-trail. The convener node and the intervening nodes are each further operable to indicate to one or more nodes on the light-trail that optical traffic is being transmitted on the light-trail.

Abstract: In the ring type optical communication system of the present invention, in each OADM arranged on a ring network, an optical signal which has the same wavelength as the add wavelength assigned to a local node, of the optical signals of each wavelength contained in WDM light input from on the ring, is extracted from a drop port Pd without being terminated by a rejection/add filter, and input to an optical switch. In the optical switch, either one of the optical signal extracted from the rejection/add filter, or the add light added onto the ring from the local node, is selected, and the selected light is applied to the add port Pa of the rejection/add filter. As a result, communication between a central station and optional OADM nodes, and multicast communication over a plurality of ring networks can be realized by means of a simple node configuration.

Abstract: Method and apparatus for dynamic provisioning of reliable connections in the presence of multiple failures in optical networks are described. One embodiment is a method for allocation of protection paths after a failure in an optical network. The method comprises, responsive to a failure in an active lightpath, switching traffic on the active lightpath to a protection path; subsequent to the switching, identifying all active lightpaths in the network that no longer have an available protection path; and attempting to allocate a protection path to each of the identified active lightpaths.

Abstract: A method for transmitting traffic in an optical network includes establishing a light-trail in the optical network between a number of nodes. The light-trail couples the nodes and is associated with one of a number of wavelengths in the network. The method also includes, at one or more of the nodes, receiving traffic from one or more client devices of the node to be communicated over the light-trail to a destination node and determining one or more service types associated with the received traffic. Furthermore, the method includes determining traffic shaping information for each service type based on information relating to the arrival of traffic associated with the service type at the node. The traffic shaping information indicating to the destination node the rate at which the traffic associated with each service type should be communicated from the destination node to one or more client devices of the destination node.

Abstract: A packet-switched WDMA ring network has an architecture utilizing packet stacking and unstacking for enabling nodes to access the entire link capacity by transmitting and receiving packets on available wavelengths. Packets are added and dropped from the ring by optical switches. A flexible credit-based MAC protocol along with an admission algorithm enhance the network throughput capacity.

Abstract: A system and method for a transparent WDM metro ring architecture in which optics enables simultaneous provisioning of dedicated wavelengths for high-end user terminals, while low-end user terminals share wavelengths on “virtual rings”. All wavelengths are sourced by the network and remotely modulated at customer “End Stations” by low cost semiconductor optical amplifiers, which also serve as transmission amplifiers. The transparent WDM metro ring architecture permits the communication of information and comprises a fiber optical feeder ring, at least one fiber optical distribution ring, a network node (NN), at least one access node (AN) said network node and said at least one access node connected via said fiber optical feeder ring and at least one end station (ES) connected via said fiber optical distribution ring to said at least one access node, wherein said user is attached to said at least one end station.

Abstract: A system and method for a transparent WDM metro ring architecture in which optics enables simultaneous provisioning of dedicated wavelengths for high-end user terminals, while low-end user terminals share wavelengths on “virtual rings”. All wavelengths are sourced by the network and remotely modulated at customer “End Stations” by low cost semiconductor optical amplifiers, which also serve as transmission amplifiers. The transparent WDM metro ring architecture permits the communication of information and comprises a fiber optical feeder ring, at least one fiber optical distribution ring, a network node (NN), at least one access node (AN) said network node and said at least one access node connected via said fiber optical feeder ring and at least one end station (ES) connected via said fiber optical distribution ring to said at least one access node, wherein said user is attached to said at least one end station.

Abstract: An apparatus for suppressing optical power transients includes a variable optical attenuator receiving an input optical signal and outputting an output optical signal; an optical power sensing element coupled to the input optical signal and sensing a portion of the input optical signal; and a feedforward loop controller coupled to the variable optical attenuator and to the optical power sensing element; the feedforward control loop providing feedforward control of the variable optical attenuator to reduce optical power transients of the input optical signal and maintain a substantially constant output power based on the input optical power and a reference value; the variable optical attenuator having a default opaque state in which the input optical signal is substantially attenuated when power is not being supplied to said variable optical attenuator. Variations include feedback loop controllers and a combination feedback and feedforward loop controllers.

Abstract: A bidirectional line switched ring network which enables high-speed operation with improved reliability because of a reduced software processing load is disclosed, and the network includes a plurality of optical transmission equipment sets connected in a ring form, wherein optical transmission equipment provided in a node on the transmission side performs transmission to each lower-order channel by attaching a transmission-side node ID, and, optical transmission equipment provided in a node on the reception side collates the received transmission-side node ID with an expected value of the transmission-side node ID having been set in advance, and when the collation does not match, the optical transmission equipment in the node on the reception side prevents a misconnection in the event of a failure by inserting an alarm indication signal.

Abstract: There is provided a method of, and apparatus for, regulating radiation component (wavelength channel) power in a wavelength division multiplexed (WDM) optical communications system (10). The system (10) comprises a plurality of nodes (20) interconnected through optical waveguides (30, 40) (optical fibers). The method is characterised by: passing one or more tokens (300) around the system from node to node; adjusting nodal settings (150, 170), such as optical attenuation, applied at each node to regulate the power of WDM radiation components at the node in response to receiving one or more tokens; and repeating the method until WDM radiation component power within the system is substantially regulated.

Abstract: An output control unit outputs data of bit rate A to a first header-attaching unit and data of bit rate B to a second header-attaching unit. An instructing unit instructs the first or the second header-attaching unit to attach a header of bit rate being the least bit rate to the data of bit rate A or B. The first header-attaching unit creates a header of bit rate A, including an ID of a destination ONU of the data of bit rate A and information concerning the data length, and attaches the header of bit rate A to the data of bit rate A. The second header-attaching unit creates a header of bit rate A, including an ID of the destination ONU of the data of bit rate B and information concerning the data length, and attaches the header of bit rate A to the data of bit rate B.

Abstract: Disclosed herein is an optical node device applicable to an optical network including a closed loop provided by an optical fiber. This optical node device includes a tunable wavelength selecting element adapted to input WDM signal light obtained by wavelength division multiplexing a plurality of optical signals having different wavelengths, the tunable wavelength selecting element having a function of dropping at least one optical signal from the WDM signal light and a function of adding at least one optical signal to at least one unassigned wavelength channel of the WDM signal light; and a wavelength selecting filter optically connected to the tunable wavelength selecting element for removing noise present in any bands other than a signal band of each optical signal passing through the tunable wavelength selecting element.

Abstract: An optical wavelength division multiplexing network has a multi-level structure where a plurality of optical network units (ONUs) are connected to a lowest-level network. A node apparatus connected to networks other than the lowest-level network includes (a) passive optical components to branch optical signals from a higher-level network to a lower-level network, and couple optical signals from the lower-level network to the higher-level network, and (b) optical amplifiers for the optical signals. A node apparatus connected to the lowest-level network includes (a) an optical multiplexer/de-multiplexer to de-multiplex optical signals from the higher-level network, selectively output an optical signal to each ONU, and multiplex wave-length specific optical signals from the ONUs into a multiplexed optical signal, and (b) optical amplifiers for the optical signals.

Abstract: A hybrid optical network comprising a single channel optical ring network with a plurality of ring nodes and a star subnetwork. The star subnetwork comprises a central wavelength router, a plurality of combiners being connected to input ports of the central wavelength router, and a subset of the ring nodes of the ring network, each node of the subset including a tunable transmitter and a tunable receiver to communicate optical data packets over the star subnetwork. Optical data packets routed between two ring nodes of the subset over the star subnetwork are assigned a specific wavelength that determines the routing of the data packets through the central wavelength router. The invention further regards a method of routing data packets between a source ring node and a destination ring node of a hybrid optical network.

Abstract: A method for protecting a cross-ring service in an optical network includes the steps of: determining whether a configured working path crosses different rings; and in the case that the working path crosses different rings, establishing a cross-ring protection path which bypasses an off-ring node or an on-ring node of the working path on a ring, and binding the cross-ring protection path and the working path, wherein the cross-ring protection path and the working path is bound, and thus a protection can be implemented for the cross-ring service when the off-ring node or the on-ring node fails, with a reduced occupancy of bandwidth in comparison with the conventional DNI method.