Abstract: To verify the integrity of optical paths through and among optical switches, optical signals are provided with co-propagating supplemental signals. The supplemental signals preferably have at least one characteristic which allows distinguishing one supplemental signal from another. Associated with a port of a switch, means are provided for detecting a supplemental signal and determining if the supplemental signal indicates that a desired optical signal is passing through the port as expected and desired. Means for imparting or changing the distinguishing characteristic of a supplemental signal may also be employed to facilitate verifying the passage of optical signals.

Abstract: A branch unit for a fiber optic system that includes a service path and a protection path, whereby the branch unit provides switching to account for problems due to fiber cuts and/or equipment failures that may occur in the fiber optic system. The service and protection paths meet at a branch point of the fiber optic network, or at a network protection equipment (NPE) that is located near a customer interface equipment. A plurality of switches are provided at the branch unit or NPE, along with a detector and a processor, to determine whether any signals are being received from the service path, and if not, to reconfigure the system to accept signals from the protection path.

Abstract: A system and method for facilitating full utilization of an ultra-wide optical communication band spanning the useable band of the optical transmission spectrum, and providing appropriate protection strategies on the same mesh/ring network for all channels within the ultra-wide optical communication band. A network node architecture includes a band splitter to receive all of the optical signals sent on various wavelengths within the wide optical communication band. The band splitter separates a first group of the optical signals from a second group of the optical signals based on their range of wavelength. The first group of optical signals are those within a first wavelength range of the optical communication band, and the second group is from the second wavelength range of the optical communication band. A cross-connect circuit receives the first and second groups of optical signals, and routes them to targeted output ports at the output section of the node.

Abstract: A method and an apparatus for switching channel connection between multiple optical channels synchronously and automatically. The apparatus employs an optical switch to interface among a plurality of optical channels, and an optical power meter to monitor data transmission over the plurality of optical channels by measuring the optical power level of optical signals over the channel. When signal transmission is detected over a specific optical channel, the optical switch is locked to the specific optical channel allowing data signals over the specific optical channel to be transmitted to a specific device or another optical channel through the optical switch. When no optical signal is detected over the channel, said optical switch will be switched to another optical channel, such that signal monitoring and switching channels among a plurality of optical channels is able to be performed synchronously and automatically.

Abstract: A technique is disclosed for performing testing of an optical device under test (DUT). According to a specific embodiment, the DUT includes a plurality of DUT optical input ports and a plurality of DUT optical output ports. The testing may be performed by an optical switching testing system (OSTS) which includes a plurality of OSTS output ports optically connected to a plurality of DUT input ports, and a plurality of OSTS input ports optically connected to a plurality of DUT output ports. Components of the OSTS are configured in order to perform a specific test on the DUT. A first test scenario is configured at the DUT. At least one optical test signal is transmitted to at least one DUT input port. Test results may then be obtained by monitoring at least one DUT output port for the presence or absence of light. The test results are then analyzed for specific characteristics.

Abstract: An optical switching apparatus is provided. Generally, a plurality of optical input switches is provided. A plurality of optical output switches is provided. A plurality of central optical switches connected between the plurality of input switches and plurality of output switches is provided. A plurality of test light sources, where each test light source is connected to an optical input switch, is provided. A first plurality of optical detectors connected to the optical output switches is provided.

Abstract: The control of the transmission of useful optical signals on different line paths of an optical transmission device is accomplished via at least one of the following features: using signal sources and signal sinks, the useful optical signals are coupled into the line paths, or are coupled out of them; at least one portion of the optical line paths is configured as normal line paths having coupling nodes via which a switchover to an alternative line path can be undertaken if a normal line path is disturbed; in addition to the useful optical signals, test signals, whose evaluation is used for the switchover between the line paths, are transmitted bidirectionally section-by-section; at least two types of test signals can be transmitted, of which a first type is used as an indicator for an intact line path and a second type as an indicator for a disturbed line path; and any switchover to an alternative line path is only undertaken if, before the detection of the disturbance, a test signal of the first type has be

Abstract: A collapsed ring fiber optic system includes a service path and a protection path provides at a shallow water portion of the fiber optic system, to deal with any fiber cuts that may occur at the shallow water portion without loss of main trunk bandwidth. The service and protection paths meet at a branch point, which is preferably located at a deep water portion of the fiber optic system. A passive combiner or a 1×2 switch is provided at the branch unit, along with a detector and a processor, to determine whether any signals are being received from the service path, and if not, to reconfigure the system to accept signals from the protection path. At another shallow water portion of the fiber optic system, nearby where a destination is located, the signal provided on the optical path over the deep water portion is split into a service path and a protection path, to provide redundancy to deal with any fiber cuts that may occur.

Abstract: Techniques for controlling and monitoring MEMS optical switches are disclosed. In one embodiment, an electronic feedback loop is employed to determine a control signal to a MEMS switch actuator in accordance with an instruction. The control signal is so determined in such a way that the switching statuses are maximally guaranteed. To generate an appropriate control signal, AC or DC impedances of the MEMS switch are detected and used to configure the control signal to drive the switch. When it is detected that the impedance changes do not meet respective thresholds, the control signal is adjusted. In the case that the stiction happens, the switch actuator is overcharged, discharged and repeatedly applied for a limited time to overcome the stiction.

Abstract: Devices, such as node and network elements for use in communications systems, which include a plurality of ports, each having an input and an output, a plurality of splitters corresponding to the port inputs, a plurality of combiners corresponding to the port outputs, a plurality of signal paths between the splitters and the combiners, wherein each of the signal paths includes a signal varying device, and a plurality of protection devices connected between the splitters and the combiners, wherein each of the plurality of protection devices includes a signal varying device and provides a protection path corresponding to a plurality of the signal paths, and wherein at least one splitter has at least one unused output after the signal paths and the protection paths are connected, and wherein at least one combiner has at least one unused input after the signal paths and the protection paths are connected.

Abstract: According to the invention, systems, apparatus and methods are disclosed for optically enabling a circuit component in a large scale integrated circuit. In one embodiment, the invention is a circuit comprising a light sensing device for producing a signal in response to sensing light, an optic function subcircuit, and a switch connected to the light sensing device and to the optic function subcircuit for activating the optic function subcircuit when light is sensed. The light sensing device is preferably a phototransistor and a light sensing circuit is preferably placed between the light sensing device and the switch for amplifying and conditioning the light sensing signal. The optic function subcircuit can be an optical modulator, an optical receiver or any other device that is to be operated and powered only when incident light is present.

Abstract: An optical network has an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit via a working optical fiber, (2) a protection OSU of a protection circuit via a protection optical fiber, and (3) one or more optical network terminals (ONTs). The present invention enables fast protection switching from the working OSU to the protection OSU. In one embodiment, the arrival times of corresponding upstream ranging reply PLOAM cells are measured at both the working and protection OSUs during ranging operations of the working OSU. In another embodiment, a cell delineation procedure is initiated at the protection OSU during normal, non-ranging operations of the working OSU to enable the protection OSU to correctly delineate upstream cells and the arrival times of corresponding upstream cells are then measured at both the working and protection OSUs.

Abstract: A transparent optical switch includes network management and performance monitoring using bit level information obtained by extracting selected information on a polling basis and analyzing the extracted information in the electrical domain. In one embodiment, a signal is injected into the switch fabric of the switch via a demultiplexing device. The injected signal is extracted at the output of the switching fabric via an N:1 switch and analyzed by a signal analyzer to verify input to output connections. In another embodiment, an optical switch includes first and second switch fabrics for 1:2 broadcast capability. In a further embodiment, an optical communication system includes a plurality of optical networks and a plurality of optical switches that cooperate to generate unequipped signals and to obtain autonomously switch-to-switch port connectivity information required for auto-topology discovery.

Abstract: Fault tolerance is provided in a cross-connect system having only duplicated switch fabrics, instead of the triplicated switch fabrics of the prior art. In addition to the two information switch fabrics, the cross-connect system has a relatively small code switch fabric which switches check-code signals generated at each input interface for each input signal sent to an information switch fabric. Fault-detection and error-recovery components in each output interface (1) generate local check-code signals for each outgoing signals received from an information switch fabric and (2) compare those local check-code signals to the corresponding check-code signal received from the code switch fabric to detect a failure and to select a healthy signal as the output signal for that output interface. In one embodiment, input and output interfaces are clustered, and the corresponding input and output check-code signals are multiplexed, for even greater savings in overhead (e.g.

Abstract: The invention relates to optical ring network comprising stations (340) which are connected to at least one optical fiber by means of the couplers, the two ends of the optical fiber being connected to a point of presence or an optical network access node. The point of presence comprises (k)at least an optical emitter (330-1) which emits a falling optical signal having at lest one first wavelength (420) in the direction of one end oft he optical fibers (455) and (ii) at least one optical receiver (330-2) which receives a rising optical signal having at least one second wavelength which is different from the first wavelength. The aforementioned optical network access node comprises mean such as a hub (320) which can be used for the communication between the optical receiver (320-2) and the optical emitter (330-1). The wavelength of rising signals and the wavelength of the following signals are shared by several stations.

Abstract: A method of calibrating a crossconnect including a MEMS device and another optical device, each of which further include a plurality of elements, the method including determining a relationship between an applied voltage and an angle response for a number of the elements of the MEMS device, determining a function of beam position and element position for the number of the elements of the MEMS device, assembling the MEMS device and the another optical device to produce the crossconnect, applying voltages to make sample connections between the MEMS device and the another optical device based on the relationship and the function, determining a transformation for the sample connections caused by packaging the crossconnect, and redetermining the relationship and the function based on the transformation. The method may be iterated more than once to achieve a more accurate determination.

Abstract: An upgradeable photonic networking apparatus and method uses components in the upgradeable photonic networking apparatus to establish a number of alternate optical paths around an upgradeable element. The upgradeable element can be replaced with a new element introduced into the number of alternate optical paths, or else the upgradeable element can be upgraded after which optical paths are restored through the upgradeable element.

Abstract: A network element is provided for an optical transport network. The network element includes: an optical spectrum analyzer (OSA) module integrated therein and operable to determine signal power data for an optical signal received therein; a plurality of monitor taps disposed at different locations within the network element, each monitor tap operable to divert a portion of the optical data signal traversing the optical transport network to the OSA module; and an optical switch interposed between the OSA module and each of the plurality of monitor taps, the optical switch receiving optical signals from each of the plurality of monitor taps and selectively operable to input one of the optical signals into the OSA module.

Abstract: An optical transmission equipment having a switchover control function of optical transmission lines enables to reduce a required space in a common equipment supervision and control portion. The optical transmission equipment includes a pair of a work interface unit and a protection interface unit each accommodating an optical transmission line, and an add drop multiplexing unit for selecting an optical signal output from either of the interface unit pair. Each interface unit includes a switchover controller, and each of the interface unit pair is mutually connected via a communication path so as to share status information among the switchover controllers. Upon a failure in the work interface unit side of the interface unit pair, the failure is reported to the protection interface unit side prepared as an object for switchover, to send a switchover request from the protection interface unit side to the add drop multiplexing unit.

Abstract: An optical signal reception control circuit which includes an identifying circuit which identifies data included in a burst optical signal and which outputs data and an envelope generating circuit which detects the start of reception of the burst optical signal and which outputs an envelope signal corresponding to a reception period of the burst optical signal. The optical signal reception control circuit also includes a fixed signal output circuit which outputs a fixed signal of a predetermined level for a null signal period in which the data is not included and a selector which selects the output of the identifying circuit when the envelope signal is outputted and which selects the output of the fixed signal output circuit when the envelope signal is not outputted.

Abstract: A flexible open ring optical network includes a plurality of nodes connected by twin or other suitable optical rings. Each node is operable to passively add and passively drop traffic from the rings. The nodes may include a transport element for each ring. The transport elements include an optical splitter element and an optical combiner element. The optical splitter element is operable to passively combine an add signal including local add traffic and a first transport signal including ingress traffic from a coupled optical ring to generate a second transport signal including egress traffic for transmission on the coupled optical ring. The optical combiner element is coupled to the optical splitter element and is operable to passively split a third transport signal including the ingress traffic to generate a drop signal including local drop traffic and a fourth transport signal including the ingress traffic.

Abstract: The method and system for testing during operation of an open ring network includes opening a ring of the network at the node. Traffic circulating on the ring is dropped in the node to a monitoring element prior to or at the opening of the ring in the node. At the monitoring element, a signal received from the ring is tested. During tested and while the ring is open, traffic continues to be communicated between each node on at least one of the ring or a second ring each connecting the nodes of the network.

Abstract: Systems and methods for reliable and low cost optical connection verification. One application is verification and monitoring of optical cross-connect performance. A connection is verified by splitting off optical signals at both ports of the connection, converting the signals to electrical signals, and then cross-correlating to verify connectivity between the ports. Lowpass filtering applied to the electrical signals may be applied to reduce the complexity of the cross-correlation.

Abstract: A device and method for detecting rotational drift of mirror elements in a MEMS tilt mirror array used in an optical crossconnect. The optical crossconnect directs optical signals from an input fiber to an output fiber along an optical path by rotatably positioning mirror elements in desired positions. A monitoring device disposed outside of the optical path is used to obtain images of the MEMS array or to transmit and receive a test signal through the crossconnect for detecting the presence of mirror element drift.

Abstract: Optical communication systems, terminal facilities of an optical communication system, optical communication methods, and methods of communicating within an optical network are provided. According to one aspect of the invention, an optical communication system includes: a plurality of optical communication conduits individually configured to communicate data communication signals; an optical switch adapted to optically couple a communication path of an associated data terminal with at least one of the optical communication conduits; and a controller configured to monitor the data communication signals and to control the optical switch responsive to the monitoring of the data communication signals.

Abstract: An optical wavelength-division-multiplexing (WDM) network has at least one transit node, where a majority of received channels are destined for a remote node, and at least one hub node, where a majority of received channels are switched to a local destination. The network follows a channel-level protection scheme, and at least one of the nodes has a cross-connect switch of a tandem design with a wavelength switch portion optically positioned in a feedback path of a space switch portion. Alternatively, the transit node has a tandem switch design, where the space switch interfaces with the network fibers, and the hub node has at least a wavelength switch that interfaces with the network fibers. The capacities of the respective wavelength and space switch portions of the tandem cross-connect are configured according to the expected ratio of local traffic to passthrough traffic.

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: Optical communications networks are provided that allow network maintainers to monitor or control subsystems using communications links other than optical telemetry links. The communications links may be wireless links or may be based on any other suitable communications links such as links using Ethernet cables or telephone lines. Network subsystems may be provided that include communications circuitry for communicating over the communications links. A network maintainer may use network control and management software implemented on computer equipment at a different location than the subsystems to communicate with the subsystems over the communications links. Because the communications links may function independently from the optical telemetry channels in the network, new subsystems may be added to the network without disturbing the existing network management software or telemetry arrangement.

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: A facility is provided to allow a supervisory message to quickly propagate through a transmission network without delay. Specifically, a supervisory message is quickly routed from one node to a next node by (a) splitting the control channel signal carrying the supervisory message at a receiving node, (b) sending one of the split control channel signals to an output via switchable apparatus for immediate transmission the next node and (c) sending the other split signal to a controller for analysis. If the controller invokes a predetermined procedure as a result of the content of the message, e.g., invokes protection switching, then the controller forms a supervisory message identifying the invoked procedure, operates the switchable apparatus so that the message identifying the invoked procedure may be routed to the output in place of the split channel signal message.

Abstract: A hybrid wireless optical and radio frequency (RF) communication link utilizes parallel free-space optical and RF paths for transmitting data and control and status information. The optical link provides the primary path for the data, and the RF link provides a concurrent or backup path for the network data, as well as a reliable and primary path for the control and status information. When atmospheric conditions degrade the optical link to the point at which optical data transmission fails, the hybrid communication link switches to the RF link to maintain availability of data communications. The switch may occur automatically, based on an assessment of the quality of the optical signal communicated through the optical path.

Abstract: A method and apparatus for measuring optical power or insertion loss within an optical cross-connect system utilizing a plurality of parallel light beams sampled at switch fabric input and output portions via imaging devices.

Abstract: Systems and methods are described for communications links with non-intrusive expansion capability. A first splitter combiner switches form a shut state to a bypass state when a second headend output is communicatively coupled to a first upstream input and a second headed output is communicatively coupled to a first downstream output. The first splitter combiner is then switchable back to the shut state from the bypass state when the either the second headend output is communicatively decoupled from the first upstream input or the second headend input is communicatively decoupled from the first downstream output. The systems and methods provide advantages because a communication network can be equipped for non-intrusive expansion of the network.

Abstract: Disclosed is a secure/non-secure bypass switch, comprising a first port for receiving input signals; a first relay having an input, a first output and a second output, said input connected to said first port, and said second output connected to a second port; a first fiber optic modem having an input and an output, said input connected to said first output of said first relay; a second fiber optic modem having an input and an output, said input connected to said output of said first fiber optic modem; and a second relay having an output, a first input and a second input, said first input connected to said output of said second fiber optic modem, said second input connected to a third port, and said output connected to a fourth port.

Abstract: A network component (3d) for an optical network (1) is described, including a coupling device (2; 4, 5) for optical coupling of the network component (3d) to the optical network (1), the coupling device (2; 4, 5) having a receiving module (4) and a transmitting module (5); a first data processing device (8, 9) which is unidirectionally connected to the receiving module (4); a second data processing device (10, 11) which is unidirectionally connected to the transmitting module (5); the first data processing device (8, 9) being unidirectionally connected to the second data processing device (10, 11) for transmitting data to the second data processing device; a detection device (4) for detecting the network status; and a two-way switch (23) for switching of the input of the first data processing device (8, 9) between the receiving module (4) and the output (19) of the second data processing device (10, 11) as a function of the network status detected.

Abstract: An optical cross connect (40) includes a database (44) which associates each of its outgoing OSCs (Optical Service Channels) with Section Traces corresponding to the ports serviced by the OSC. Periodically, the optical cross connect (40) transmits the associated Section Traces over each OSC to inform a receiving optical cross connect (40) of the channels in the channel group associated with the OSC. Any changes in configuration of the outgoing channels of an optical cross connect cause the Section Traces to be updated automatically.

Abstract: A diagnostic monitoring system for a WDM network, the system comprising an electrical non-blocking cross-connect switch having a plurality of demultiplexer ports, a plurality of multiplexer ports, at least one tributary receiver port, at least one tributary transmitter port, and at least one diagnostic port; and at least one multi-protocol performance monitoring unit connected to one of said at least one diagnostic ports such that said at least one multi-protocol performance monitoring unit, in use, can selectively monitor one of said demultiplexer or tributary receiver ports whereby said system, in use, supports multi-protocol intrusive monitoring of a test signal and multi-protocol non-intrusive monitoring of live traffic at said at least one demultiplexer or tributary receiver port

Abstract: An optical crossconnect selectively connects at least one input terminal with at least one output terminal. The optical crossconnect includes: an optical switch connecting at least one input port connected to the at least one input terminal with at least one output port connected to the at least one output terminal; at least one supervisory light generating circuit for sending a supervisory light from each of the at least one output port to the optical switch; and at least one supervisory light receiving circuit for receiving the supervisory light output from the at least one input port.

Abstract: Apparatus and methods for switching N optical input signals to M optical outputs are disclosed. In an example, an apparatus includes a plurality of optically transparent fabrics. Each of the fabrics receive at least one optical input signal and switch that received signal to at least one of a plurality of intermediate outputs. A multiplexer is operatively coupled between the intermediate outputs of the plurality of optically transparent fabrics and the M optical outputs.

Abstract: Optical transmission systems of the present invention include optical protection systems, apparatuses, and methods that provide increased reliability in the system. The optical system generally includes an optical switch having distinct, cooperating dedicated and shared protection sections. The shared protection sections in a plurality of nodes can be configured to provide a protection net, in which a plurality of traffic demands, or working channels, are commonly protected as protection group using one protection channels supported by the protection net.

Abstract: The present invention is a method to protect a cross-connect OXC/OEXC used to forward at least one signal AB from a main input IN to a main output OUT. Said method comprises the following step: dividing the at least one signal AB into two substantially identical signal parts, a first signal part A and a corresponding signal part B; routing the at least one first signal part A through a first cross-connect OXC1/OEXC1, from the input IN to the output OUT; detection of a failure affecting the at least one first signal part A; interruption of the routing path for the at least one first signal part A; routing the at least one corresponding signal part B through a second cross-connect OXC2/OEXC2, from the input IN to the output (OUT).

Abstract: An optical device under test—DUT—having m inputs, with m=1, 2, 3, . . . , M, and n outputs, with n=1, 2, 3, . . . , N, is tested by applying a plurality of different characteristic stimulus signals to at least one of the m inputs. A response signal is received at at least one of the n outputs, and a property of the DUT can be determined or verified by evaluating the received response signal in conjunction with at least one of the applied stimulus signals or at least an indication thereof. The plurality of different characteristic stimulus signals are provided in a way allowing tracing each respectively applied stimulus signal in each received response signal—if present or beyond a detectability threshold.