Abstract: A method for monitoring lightpaths in an optical network comprising nodes interconnected by wavelength-multiplexed links is disclosed. Each lightpath is identified by a respective optical signature. A node stores identifiers of optical signatures of lightpaths designated to traverse the node and identifiers of adjacent nodes. Each node also maintains a record of all optical signatures it detects. A command-line interface associated with a selected node tracks a selected lightpath, designated to traverse the selected node, by propagating messages in an upstream direction, a downstream direction, or both, requesting other nodes to provide information pertinent to the selected lightpath. The selected node may also send messages to all its neighboring nodes requesting each to indicated detection, or otherwise, of the selected lightpath.

Abstract: An optical transmission apparatus includes optical transmitters for transmitting optical signals and first monitor units for monitoring optical signals from the optical transmitters. A multiplexer is provided for multiplexing the optical signals from the optical transmitters into a multiplexed signal. A second monitor unit is provided for monitoring each optical signal which is multiplexed in the multiplexed signal from the multiplexer. A processing unit is provided for comparing a first number of optical signals detected by the first monitor units and a second number of optical signals detected by the second monitor unit.

Abstract: In a wavelength division multiplexed (WDM) optical communication system having optical transmitters and receivers communicating via a optical channels, the bit error rate (BER) for the optical channels is tested simultaneously by performing a BER measurement for the cascaded chain. A BER test signal is supplied from a BER tester to a first optical transmitter. The BER test signal passes through the optical channels. The last optical receiver in the cascaded chain supplies the test signal to the BER tester measure the BER. The measured BER is compared to a predetermined system BER threshold to determine if the optical channels meet their specified BER values. Each optical transmitter and receiver includes a performance monitoring circuit that monitors the quality of the BER signal supplied to the optical transmitter/receiver for identifying one or more optical channels that the measured BER exceeds a predetermined system BER threshold.

Abstract: Disclosed is an apparatus for monitoring failure positions on fibers in a WDM-PON system and a WDM-PON system having the apparatus.

Abstract: Provided is an apparatus for testing the performance of an optical transceiver by referencing various performance clocks provided by an OTU2 signal connection transceiver and an STM-64/OC-192 signal. The apparatus for testing performance of an optical transceiver includes: a transmitter/receiver reference clock selector for selecting one of various transmitter/receiver reference clocks provided by an STM-64/OC-192 connection optical transceiver or an OTN connection optical transceiver; a transmitter test reference clock selection switch for selecting a receiver data synchronous clock provided by the transceivers or the selected transmitter/receiver reference clock as a transmitter test reference clock; and a receiver test reference clock selection switch for selecting a transmitter supervisory clock provided by the transceivers or the selected transmitter/receiver reference clock as a receiver test reference clock.

Abstract: An apparatus for shared optical performance monitoring (OPM) is provided. A wavelength sensitive device receives light at an input port and routes it wavelength selectively to a set of output ports. To perform optical performance monitoring on the output ports, a monitoring component of each output signal is extracted, and these monitoring components are then combined. A single OPM function is then performed on the combined signal. However, with knowledge of the wavelengths that were included in each output signal, a virtual OPM function can be realized for each output port. The per port functionality can include total power per port, power per wavelength per port, variable optical attentuation, dynamic gain equalization, the latter two examples requiring feedback.

Abstract: A transmission apparatus that receives an optical signal by selecting any one of a plurality of provided optical signal transmission paths through protection control is configured to include a plurality of optical signal outputting sections that output the optical signals transmitted through said optical signal transmission paths respectively as optical signals having wavelengths that are different from each other, a wavelength selective optical switch capable of selectively outputting light of a wavelength corresponding to any one of the optical signals coming from the optical signal outputting sections on the basis of the frequency of a controlling frequency signal, and an optical switch controlling section that supplies said controlling frequency signal to the wavelength selective optical switch so as to output the optical signal coming from the optical signal transmission path side that is selected by said protection control among the optical signals coming from the optical signal outputting sections.

Abstract: A method and system provide capacity-efficient restoration within an optical fiber communication system. The system includes a plurality of nodes each interconnected by optical fibers. Each optical fiber connection between nodes includes at least three channel groups with different priority levels for restoration switching in response to a connection failure. The system maintains and restores full-capacity communication services by switching at least a portion of the channel groups from a first optical fiber connection to a second optical fiber connection system based on the priority levels assigned to the channel groups. Service reliability is effectively maintained without incurring additional costs for dedicated spare optical fiber equipment by improving idle capacity utilization.

Abstract: A wavelength-division multiplexed self-healing passive optical network is capable of detecting cut-off and deterioration of feeder fiber and distribution fiber and restoring a network with a star structure. The network includes a central office, a remote node, and a plurality of subscriber units. Working and protection feeder fibers connect the central office to the remote node. A reflection unit at an end of the remote node connects to the central office for reflecting a monitoring optical signal transmitted from the central office. An output monitor stage at an end of the central office connects to the remote node for detecting the reflected monitoring optical signal and generating a control signal based on the presence of abnormality of the working and protection feeder fibers.

Abstract: The present invention is a miniature camera robot which can be placed entirely within an open space such as an abdominal cavity. The instant camera robot has pan and tilt capabilities, an adjustable focus camera, and a support component for supporting the robot body. In particular embodiments, the camera robot further contains a light source for illumination and a handle to position the camera robot. A system and method for using the instant camera robot are also provided.

Abstract: Methods and apparatus for constructing phased array antenna beamforming networks are provided, that allow to scan multiple beams and select appropriate sets of delay lines simultaneously. The beamforming networks disclosed herein generate less losses than conventional ones and in some cases, do not require active switching, making them completely passive. Three main methods are comprised in the invention: (1) laser wavelength hierarchies, (2) arrangements of Wavelengths Division Multiplexing (WDM) components, (3) re-use of laser wavelengths. Multiple laser wavelengths are arranged in groups and subgroups (wavelength hierarchies) in the wavelength domain. By switching between these wavelength groupings, the arrangements of WDM components disclosed herein enable the beamforming network to direct the beam signals to the proper time delay lines, and to differentiate multiple beams.

Abstract: An optical network includes a plurality of subnets. The subnets each include a plurality of add/drop nodes coupled to the optical ring and operable to passively add and drop traffic to and from the optical ring. The network further includes a plurality of gateway nodes. The gateway nodes are each coupled to the optical ring at a boundary between neighboring subnets and operable to selectively pass and terminate wavelengths between subnets to allow wavelength reuse in the subnets and to provide protection switching.

Abstract: An optical network includes an optical ring and at least three subnets. Each subnet includes a plurality of add/drop nodes coupled to the optical ring. The add/drop nodes are operable to passively add a first traffic stream in a first direction on the optical ring and a second traffic stream in a second direction on the optical ring. The first traffic stream comprises different content than the second traffic stream, and the first traffic stream and the second traffic stream are transmitted on the same wavelength. The network also includes a plurality of gateway nodes. The gateway nodes are each coupled to the optical ring at a boundary between neighboring subnets and are operable to selectively pass and terminate wavelengths between subnets to allow wavelength reuse in the subnets.

Abstract: A network is protected against interruption of service while one or more faulty switches or optical fiber transmission lines are repaired or replaced, by an interconnecting configuration of small N×N optical input/output switches, where N is 2 or greater than 2. The switches are configured among protection and working transmission lines. The small number of fibers for each switch improves repair and installation connection reliability and permits configurations that flexibly meet differing requirements. Also the fault is monitored with a fault check signal.

Abstract: A protection arrangement for an optical switching system includes protection switching for switch planes in the optical core and for ports in the tributary cards. For a multiple layer switch core protection is also provided between layers. A first layer is for switching optical channels. The protection switches used may be 1×N, 2×N or 3×N MEMS optical switches. The 1×N MEMS provides for protection switching. The 2×N MEMS provides protection switching and testing capability. The 3×N MEMS provides for protection switching, testing and backup of the protection switching. Application of these protection switches is shown in lambda plane switch cores, multiple layer switch cores and combined switch cores.

Abstract: The invention describes methods and systems for monitoring the performance of an optical network by marking a group of optical signals with a set of identification tags which are unique to network characteristics. In the preferred embodiments, fiber identification (FID) and bundle identification (BID) tags are encoded into optical signals by marking an optical signal with low frequency dither tones whose frequencies are unique to the fiber section and to a bundle of fibers respectively. Detecting of the FID and BID tones provides more effective and accurate monitoring of performance of the optical network and allows determining of the network topology, e.g. paths of optical channels and traffic load through different fiber sections in the network. Other sets of hierarchically arranged identifiers encoded into optical signals have also been proposed, including band, conduit, city, region, country, etc. identifiers, as well as identifiers related to network security and service characteristics.

Abstract: Method and apparatus for fault localization in an optical network using time trend correlation of end node performance parameters and intermediate node performance parameters, such as QoS and quasi-Q factors, respectively. The method and apparatus are bit-rate and protocol independent, enabling testing for each channel of a diverse dense wavelength division multiplexed traffic system using a single set of hardware.

Abstract: An apparatus and method for analyzing the spectrum of a wavelength division multiplexed (WDM) optical signal, in wavelength division multiplexing (WDM) optical transmission systems, are provided. An optical filter includes an input unit for receiving a wavelength division multiplexed (WDM) optical signal via an optical transmission medium and outputting optical signals that have different incidence angles according to the wavelengths of the optical signals. Also, the optical filter includes a filter for receiving the optical signals from the input unit and separating the WDM optical signal into optical signals having different wavelengths using the difference between resonance lengths according to the different incidence angles.

Abstract: An alarm control method allowing easy localization of a failure in an optical communications network is disclosed. An optical signal from a signal transmitter is monitored to produce an alarm information signal indicating whether the optical signal is normally inputted. The optical signal and an optical control signal including the alarm information signal is multiplexed and transmitted to an optical receiver through an optical transmission line. When receiving the optical control signal and the optical signal from the optical transmitter, the optical receiver determines whether the optical signal is normally received. When not normally received, transmission of a receiver-side alarm signal to a management system is controlled depending on whether the alarm information signal indicates that the optical signal has been normally inputted at the optical transmitter.

Abstract: A method for the protection of fiber optic ring-shaped transport networks, the networks including network elements connected by spans, optical paths being installed between the network elements, the method including the steps of providing each network element with information concerning the network architecture; providing each network element with information concerning configuration data of the network elements; providing each network element with information concerning criteria for triggering the mechanism; establishing an information exchange protocol comprising a set of messages and of rules; establishing a traffic rerouting method, wherein the configuration data include the ring map, the traffic map, the wavelength and the bit rate concerning every path.

Abstract: Channels in an optical network that carry optical signals are evaluated using signal characteristics and suitable channels are compared to identify the channels that represent a single conversation using matching criteria. In another aspect, only channels that carry optical signals representing conversations of interest are compared.

Abstract: Power of scattered light separated from an optical transmission path is monitored, part of the excitation light is separated and power thereof is monitored, power of reflected light which passes in a direction opposite to a direction in which signal light passes through the optical transmission path is monitored, and, when monitored power of an excitation light reaches a predetermined determination value, whether or not any loss point occurs is determined, based on a ratio between the monitored power of the scattered light and the monitored power of the reflected light.

Abstract: The invention describes methods and systems for monitoring the performance of an optical network by introducing a fiber identification (FID) tag and/or bundle identification (BID) tag which are unique to the fiber section and to the bundle of fibers respectively. The FID tag is introduced by marking an optical signal, traveling through a section of fiber, with a low frequency dither tone whose frequency is unique to the fiber section. Similarly, the BID tag is introduced by marking an optical signal, traveling through a section of fiber in a bundle of fibers, with another low frequency dither tone whose frequency is unique to the bundle section. Detecting of the FID and BID tones either alone or along with an optionally introduced channel identification (CID) tone is provided.

Abstract: For exact level balancing or signal-to-noise ratio balancing of received signals in a wave-length-division multiplex transmission system, the associated transmitted signal power levels are adjusted. If the maximum permissible dynamic range is exceeded, the individual transmitted signal power levels are compressed, while the total transmitted signal power level is kept at least approximately constant.

Abstract: An optical network monitor and a method for monitoring the optical signals of an optical network including a spectrograph that includes a detector array, a processor and outputs. The network monitor receives an optical input signal which includes individual channels. The optical signal is transmitted onto the spectrograph which disperses the optical signal into the individual channels. The individual channels are directed onto the detector array so that the channels are spaced across the detector array. The detector array detects the channels in parallel and transmits to the processor channel parameter data which is processes the parameter data through internal algorithms to produce the outputs.

Abstract: A protection arrangement for an optical switching system includes protection switching for switch planes in the optical core and for ports in the tributary cards. For a multiple layer switch core protection is also provided between layers. A first layer is for switching optical channels. The protection switches used may be 1×N, 2×N or 3×N MEMS optical switches. The 1×N MEMS provides for protection switching. The 2×N MEMS provides protection switching and testing capability. The 3×N MEMS provides for protection switching, testing and backup of the protection switching. Application of these protection switches is shown in lambda plane switch cores, multiple layer switch cores and combined switch cores.

Abstract: A method for monitoring the transmission quality of an optical transmission system, such as, for example, an optical wavelength division-multiplex network. An amplitude histogram of an optical signal (transmission signal) transmitted over the transmission system may be plotted and classified, with the assistance of a neural network, according to bit error rates and/or causes of faults. The need for setting requirements for transmission mode, transmission format and/or transmission timing cycle of the transmission system may be eliminated. The amplitude histogram may be implemented for any signal, and causes of faults, which are not able to be determined by a conventional bit rate classification, may be allocated.

Abstract: A system and method for optical power transient control and prevention in communication networks. An optical signal propagating on a network is demultiplexed into individual spectral bands, e.g. at an OADM, and an optical power monitor point is included into each band. A separate idler laser is provided for each OADM band. The power output of each laser is adjusted such that it compensates for the signal power lost from each band. The wavelength of each laser is chosen to fall within the associated OADM spectral band, but outside of the window of individual signal wavelengths, so that it may propagate through the network without causing deleterious interference at the receiver.

Abstract: An arrangement and a method for testing a telecommunications circuit over Dense Wavelength Division Multiplexing (DWDM). A transmitter, which is optically coupled to the circuit, transmits a test-drive signal on the circuit. Through a network, a performance of the circuit is monitored at points along the circuit based on the transmitted test-drive signal.

Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=1˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.

Abstract: An optical ring is provided for propagating optical signal pairs over wavelength connections between nodes. Each optical signal pair includes two signals at different wavelengths. At one or more of the nodes, one signal of the pair acts as a transmit signal and the other acts as a receive signal. If a failure is detected the optical signal pair is redirected over a protection path without changing the wavelengths of the transmit and receive signals. This may be achieved by reversing a propagation direction for each of the signals comprised by the redirected optical signal pair.

Abstract: An OPC generates a pump light having the wavelength &lgr;s with a power larger than a threshold for generating a nonlinear effect in an optical fiber for a main signal having the wavelengths &lgr;1 through &lgr;4 transmitted from an OS, and wavelength-multiplexes the generated light with the main signal. When the pump light induces a nonlinear effect, a signal light having the wavelengths &lgr;1′ through &lgr;4′ is generated symmetrically to a main signal having the wavelength &lgr;1 through &lgr;4 about the pump light on a wavelength axis. Thus, in a wavelength multiplexing system designed based on an eight-wave transmission, a signal light can function as a compensation light even when only four waves are used at the initialization of the system, thereby compensating for the characteristics of the system operations. Furthermore, the system is effective in cost because it simply requires an OPC for generating a pump light regardless of the number of compensation lights to be generated.

Abstract: There is provided a method for testing an optical fiber link. The method includes employing a wavelength division multiplexer (WDM) to receive a signal via a port of the WDM and multiplex the signal onto the optical fiber link. The signal is used in a test of the optical fiber link. There is also provided an arrangement of components for testing the fiber link.

Abstract: An optical telephone and communication system with interferometers at the transmitter and receiver can use optical time-delay difference and differential frequency shift modulation and multiplexing techniques. The power to the system is provided from either a remote optical source through the optical network or a local optical source. The optical network provides one or two optical connections to the sets. Part of the optical signal from the network is converted to electrical energy stored in a rechargeable battery. The optical sources used have a known coherence function, wavelength and coherence length Lc. The transmitter converts the information to phase variation in one arm of the transmitter interferometer and the receiver recovers this signal by using a matched interferometer. The path imbalance between the two arms of either interferometer is greater than Lc. Each set is assigned a particular time delay difference and/or differential frequency shift for addressing.

Abstract: An arrangement and a method for testing a telecommunications circuit over Dense Wavelength Division Multiplexing (DWDM). A transmitter, which is optically coupled to the circuit, transmits a test-drive signal on the circuit. Through a network, a performance of the circuit is monitored at points along the circuit based on the transmitted test-drive signal.

Abstract: Multiple signals are monitored, for example, by an instrument used for monitoring wavelength division multiplexing (WDM) transmission systems. For each monitored frequency channel, an active mask is initialized. The active mask includes an operating window defined by a minimum frequency, a maximum frequency, a minimum amplitude and a maximum amplitude. Each signal is monitored to determine when the signal strays outside the operating window. An alarm is generated when the signal strays outside the operating window.

Abstract: The present invention relates to an automatic retrieval method of a wavelength-division multiplexed (WDM) ring network to the normal state after recovery of a failure. More specifically, the present invention relates to an automatic retrieval method of a WDM ring network to the normal state after recovery of a failure by inducing a lasing by making the gain of the closed loop larger than 1 using the fact that the recovered section in the ring network forms a closed loop immediately after the recovery of the failure.