Abstract: An arrangement in a node in a WDM-PON and a method therein for supervision of the WDM-PON are provided. The arrangement comprises X splitters of splitting ratio 1:Y, each splitter having one input and Y outputs such that X*Y equals N, wherein X, Y, N are integers. The one input of each of the X splitters is configured to receive an Optical Time Domain Reflectometry, OTDR, signal and to split the received OTDR signal into Y OTDR sub-signals such that a total of N OTDR sub-signals are outputted from the X splitters. The arrangement further comprises an N*N Arrayed Waveguide Grating, AWG, and a first filter configured to mix a feeder signal comprising data communication from an Optical Line Termination, OLT, with one of the N OTDR sub-signals. One input of the AWG is configured to receive the mix of the feeder signal and the one OTDR sub-signal, and the remaining N-inputs of the AWG are each configured to receive a respective one of the N-remaining OTDR sub-signals.

Abstract: An apparatus comprising an optical transmitter, a coarse tuner coupled to the optical transmitter and having a first tuning range, a fine tuner coupled to the optical transmitter and having a second tuning range smaller than and within the first tuning range, a wavelength division demultiplexer coupled to the optical transmitter and to a plurality of optical fibers, and a detector coupled to the optical transmitter and the wavelength division demultiplexer. A network component comprising at least one processor configured to implement a method comprising detecting an Optical Time Domain Reflectometry (OTDR) signal spectrum that has a modulated pattern, and detecting a reflected OTDR signal spectrum that has a shifted modulated pattern comprising a frequency shift with respect to the OTDR signal spectrum and a time shift proportional to the frequency shift.

Abstract: A network monitoring module for deployment in a branched optical network at a split location where the network splits into a plurality of branches, the network monitoring module is disclosed, comprising an array of transmitters for generating optical test signals, an output of each transmitter in the array being optically connected to a respective branch, a detector for receiving a remotely generated optical trigger signal which identifies a particular one of the transmitters, and a CMOS circuit for selectively triggering the transmitter identified in the optical trigger signal to transmit an optical test signal into the branch connected to that transmitter.

Abstract: A small form factor pluggable (SFP) device has an embedded optical time domain reflectometer (OTDR) for detecting anomalies along an optical fiber. The SFP device has a plurality of optical subassemblies (OSAs) that are used to transmit an optical data signal at a first wavelength, transmit an optical OTDR signal at a second wavelength, and receive an optical data signal at a third wavelength. The OTDR signal is effectively isolated from the data signals based on wavelength, and samples of returns of the OTDR signal are analyzed to detect at least one anomaly along the optical fiber.

Abstract: In one embodiment, an apparatus comprising an optical transmitter, having an optical transmitter portion and an electrical transmitter portion, and configured to convert an electrical signal to an optical signal, and transmit the optical signal; an optical receiver, having an optical receiver portion and an electrical receiver portion, configured to receive an optical signal and convert the optical signal to an electrical signal; a passive power controller configured to passively detect whether or not a cable is coupled with the optical transmitter and, if not, to place at least the optical transmitter portion in a sleep mode.

Abstract: In optical communication systems, an optical signal which is modulated with a data signal is transmitted from an optical transmitter, and is launched into a fiber-optic transmission link. The present invention provides a method and an apparatus for the measurement of the distribution of the reflectivity along an optical transmission line implemented by using the signal processing based on the cross-correlation function between the data signal with which the optical transmitter is modulated and the back-reflected signal returned to the optical transmitter to provide the in-service monitoring of the fiber-optic transmission link.

Abstract: An OLT operable in a PON and structured to perform OTDR measurements. The OLT comprises an electrical module for generating continuous downstream signals and processing received upstream burst signals according to a communication protocol of the PON; an optical module for transmitting continuous optical signals over a first wavelength, receiving optical upstream burst signals over a second wavelength, and transmitting optical upstream burst signals over a third wavelength, wherein the optical module further includes an ONU traffic processing module being electrically coupled to the optical module and the electrical module, wherein the ONU traffic processing module is configured to emulate one of a plurality of ONUs of the PON, to generate an analysis pattern to be transmitted as an optical upstream burst signal over a third wavelength, and analyze an analysis pattern received in an optical upstream burst signal for the purpose of performing the OTDR measurements.

Abstract: An approach is provided for integrating one or more fiber switches in a passive optical network. A platform generates a command signal to control a splitter hub of a passive optical network, the splitter hub being configured to communicate with a plurality of optical network terminals that respectively serve a plurality of customer premises. The splitter hub includes a fiber switch configured to provide switching between one of a plurality of input ports and one of a plurality of output ports of the splitter hub.

Abstract: An in-band OTDR uses a network's communication protocols to perform OTDR testing on a link. Because the OTDR signal (probe pulse) is handled like a data signal, the time required for OTDR testing is typically about the same as the time required for other global network events, and is not considered an interruption of service to users. A network equipment includes an optical time domain reflectometry (OTDR) transmitter and receiver, each operationally connected to a link to transmit and receive, respectively, an OTDR signal. When an OTDR is to be performed, a network device operationally connected to the link actuates the OTDR transmitter to transmit the OTDR signal on the link during a determined test time based on a communications protocol of the link, during which data signals are not transmitted to the network equipment. A processing system processes the OTDR signal to provide OTDR test results.

Abstract: Described herein are systems and methods for enhancing the resolution of an optical time-domain reflectometer (“OTDR”). One embodiment of the disclosure of this application is related to a device, comprising an optical measuring component collecting a first set of measurement data from a forward trace along an optical fiber with the optical measuring device using depolarized light, and a processing component calculating loss along the length of fiber. The optical measuring device further collects a second set of measurement data from a backward trace along the optical fiber with the optical measuring device using depolarized light.

Abstract: An optical line monitoring apparatus, including: a group information recording portion which records group information about to which splitter respective terminators are connected; a normal information recording portion which records intensities of reflected lights from a plurality of terminators in a state in which a failure is not occurring in optical lines; a monitored information recording portion which records intensities of reflected lights from the plurality of terminators in failure monitoring time; an attenuation amount determination portion which determines a terminator the reflected light intensity of which is attenuated compared with the corresponding reflected light intensity in normal information; and a control portion which determines, if the intensities of the reflected lights of all the terminators connected to the same splitter are attenuated by the same value, that a failure has occurred between the test apparatus and the splitter to which all the terminators are connected.

Abstract: The present invention provides an optical signal-selection switch module which is used in a method for simultaneous real-time status monitoring and troubleshooting of a high-capacity single-fiber hybrid passive optical network that is based on wavelength-division-multiplexing techniques.

Abstract: The present invention provides a bidirectional optical signal traffic-directing and amplification module which is used in a method for simultaneous real-time status monitoring and troubleshooting of a high-capacity single-fiber hybrid passive optical network that is based on wavelength-division-multiplexing techniques.

Abstract: In a transmission path monitoring system, a first add section adds a first add signal to a first wavelength division multiplexing signal. A first drop section separates a first drop signal from the first wavelength division multiplexing signal. A first loopback section transfers a monitor signal on a first drop optical transmission path onto a second add optical transmission path. A second add section adds a second add signal to a second wavelength division multiple signal. A second drop section separates a second drop signal from the second wavelength division multiplexing signal. A first communication section transmits the first add signal and the monitor signal and receive the second drop signal and the monitor signal.

Abstract: A system and method is disclosed that allows for the monitoring, analyzing and reporting on performance, availability and quality of optical network paths. The correlation of PM parameter metrics to client connections, coupled with threshold-based alarm generation provides a proactive and predictive management, reporting and analyzing of the health and effectiveness of individual path connections to alert Operational Support (OS) staff and/or customers to signal degradation and impending Network Element (NE) failures. The system and method performs in real-time processing intervals required for alarm surveillance in a telecommunications network.

Abstract: An optical line monitoring apparatus, including: a group information recording portion which records group information about to which splitter respective terminators are connected; a normal information recording portion which records intensities of reflected lights from a plurality of terminators in a state in which a failure is not occurring in optical lines; a monitored information recording portion which records intensities of reflected lights from the plurality of terminators in failure monitoring time; an attenuation amount determination portion which determines a terminator the reflected light intensity of which is attenuated compared with the corresponding reflected light intensity in normal information; and a control portion which determines, if the intensities of the reflected lights of all the terminators connected to the same splitter are attenuated by the same value, that a failure has occurred between the test apparatus and the splitter to which all the terminators are connected.

Abstract: Reduction in power consumption at low costs is realized by a system with apparatuses connected with each other. A switch device comprises transmission/reception unit each connected to each of apparatuses through a communication cable for transmitting/receiving a signal to/from each apparatus, and a connection switching unit for switching connection between the apparatuses by switching connection between the transmission/reception unit. Further provided are a reception state monitoring unit for monitoring a signal reception state of the transmission/reception unit, and a transmission stopping unit for executing signal transmission stopping processing according to a monitoring result obtained by the reception state monitoring unit with respect to other transmission/reception unit to which connected through that communication cable is other apparatus having a connection relationship with the apparatus to which the transmission/reception unit is connected through the communication cable.

Abstract: A system and methods include generating an optical time domain reflectrometry signal; transmitting the optical time domain reflectrometry signal on a first fiber path in a first direction through at least one optical amplifier; receiving a reflection of the optical time domain reflectrometry signal on the first fiber path in a second direction opposite the first direction; transmitting the reflected optical time domain reflectrometry signal on a second fiber path in the second direction, where the second fiber path is not the first fiber path; and determining a location of a fault on the first fiber path based on the reflected optical time domain reflectrometry signal.

Abstract: An optical transmission device for controlling an optical signal output includes a return light detection section for detecting return light of the optical signal transmitted via the optical transmission line; a superimposed light transmission section for generating superimposed light having a superimposed basic low-frequency wave and transmitting the light when return light is detected by the return light detection section; a return light identification section for identifying the return light detected by the return light detection section as Fresnel light caused by a disconnection of the optical connector or Stokes light caused by stimulated Brillouin scattering based on an analysis result of the return superimposed light with respect to the superimposed light transmitted by the superimposed light transmission section.

Abstract: Systems are provided for gathering location data pertaining to a fiber optic network. One system includes a sensor, a geolocation system, a processor in communication with the sensor and the geolocation system, and a user control panel. The sensor is configured to receive an operational input indicating the condition of a network, and the geolocation system is configured to determine the location, such as a latitude and longitude, of the optical fiber. The processor is configured to associate outputs from the sensor and the geolocation system. The processor may be configured to store the outputs on a storage media. A transmitter may also be provided to transmit the data to a remote location for analysis and display. An associated method for gathering location data is also provided.

Abstract: An apparatus comprising an optical transmitter coupled to an optical fiber, and an optical receiver coupled to the optical fiber, wherein the transmitter is configured to transmit a test signal data pattern and user data into the optical fiber, and wherein the receiver is configured to receive a reflection of the test signal data pattern. Also disclosed is a network component comprising a processor configured to implement a method comprising promoting the transmission of an optical test signal data pattern into an optical fiber, wherein the test signal data pattern creates a radio frequency (RF) tone, and detecting a reflection of the RF tone in the optical fiber.

Abstract: Provided are an instantaneous interruption monitoring system and an instantaneous interruption monitoring program for a computer incorporating a non-real time operating system (OS). Measurement results acquired from optical time domain reflectometers (OTDR) can be continuously stored and the occurrence of an instantaneous interruption can be reported in real time. The system includes an instantaneous interruption monitoring program that determines the occurrence of an instantaneous interruption on a communication line, records instantaneous interruption information, and reports the occurrence of an instantaneous interruption.

Abstract: The invention relates to a method for detecting a check-back signal in a transmission system for optical signals. According to said method, a constant proportion of the output in a defined frequency range of the check-back signal is concentrated in a narrow-band spectral range and is determined after a transmission phase by means of a narrow-band detection of the concentrated energy around the spectral range. If no signal is identified during the narrow-band detection, a line interruption is determined and no pump source is switched on for safety reasons. The narrow-band detection of the check-back signal also allows the transmission attenuation of the transmission system to be measured.

Abstract: A mechanism for adjusting or shutting off an optical signal within a network system is provided. The system may include a generating element for providing an optical signal and a bi-directional coupler for transmitting the optical signal to downstream components and fiber links and for transmitting a reflected optical signal based on the reflection characteristics of the downstream components to a converter element. The converter element converts the reflected optical signal to an electrical trigger signal that is used by a processing element to monitor the degradation or operational conditions within the network system. Based on the electrical trigger signal the processing element may adjust or shut off the optical signal at the generating element or at another element within the network system or another network system. The processing element may also send a communication signal to other elements or an operator to indicate unacceptable noise within the network system.

Abstract: A bidirectional optical module according to the present invention comprises light emitting elements 110, 130 that emit light to enter an optical fiber 71, a light receiving element 190 that receives light having exited the optical fiber 71 and a light branching element 160 that guides the light having exited the optical fiber 71 onto the light receiving element 190. It further includes a stray light shielding member 185 disposed between the light branching element 160 and the light receiving element 190 and having formed therein an opening 186, through which the light to enter the light receiving element 190 passes. The stray light shielding member 185 blocks stray light 100b while light 100a having exited the fiber 71 passes through the opening 186. Therefore, any increase in the extent of error in the detection of the returning light level or the position of a reflecting point is prevented.

Abstract: Embodiments of the invention include an active optical cable and method for controlling the operation of the active optical cable based on the detection of signal loss, e.g., due to fiber breakage, within the active optical cable. The active optical cable includes first and second optical transceivers, each with an open fiber control module coupled between the transmission side and the receiver side of the respective optical transceiver. The transmission side of each optical transceiver is coupled to the receiver side of the other optical transceiver via a plurality of transmission channels, such as a plurality of optical fibers. Each open fiber control module is configured to detect an optical power level of an optical signal received by the receiver side of the optical transceiver within which the open fiber control module resides and, based on such detection, control the operation of the corresponding transmission side of the optical transceiver.

Abstract: A method and apparatus is provided for obtaining status information from a given location along an optical transmission path. The method begins by generating a cw probe signal having a prescribed frequency that is swept over a prescribed frequency range. The cw probe signal is transmitted over the optical path and a returned COTDR signal in which status information concerning the optical path is embodied is received over the optical path. A receiving frequency within the prescribed frequency range of the returned COTDR signal is detected to obtain the status information. The detecting step includes the step of sweeping the receiving frequency at a rate equal to that of the prescribed frequency. A period associated with the receiving frequency is temporally offset from a period associated with the prescribed frequency.

Abstract: The subassembly includes a laser for emitting signals towards fibers to be monitored, a passive alignment carrier, a photodetector for monitoring reflected laser signals from the fibers and for monitoring laser output power, and an optical fiber. The laser is disposed within the passive alignment carrier. The optical fiber is embedded in the passive alignment carrier, and has an angled fiber facet. The laser emits signals toward and through the angled fiber facet, whereby a portion of the laser signal illuminates the photodetector, and another portion illuminates the fibers that are being monitored and reflects back to the photodetector such that faults on the fibers can be detected.

Abstract: A component for an optical communication network comprises a source (6) for an optical communication signal, an output port (11) for outputting the optical communication signal on an optical transmitting fiber (1), a light sensor (14; 15) and an optical circulator (9) for transmitting the optical communication signal from the source (6) to the output port (11) and for transmitting light reflected or received from outside at the output port (11) to the light sensor (14; 15). The light sensor (14, 15) has an evaluation circuit (13) connected to it for detecting a time delay between a time marker of a light signal from the source and the corresponding time marker of the light arriving at the light sensor (14; 15).

Abstract: Optical Time-Domain Reflectometer (OTDR) troubleshooting of a passive optical network (PON) can be enhanced by deploying cascaded splitters, at least some of which have multiple inputs. That is, at least some of the splitters in the PON have not only a first input coupleable to the optical line terminator (OLT) or output of another splitter but also a second input directly coupleable to an Optical Time-Domain Reflectometer (OTDR). Optical time-delay reflectometry can be performed upon a selected portion or segment of the PON by selecting a splitter and transmitting an optical test signal from the OTDR directly to the input of the selected splitter and analyzing the reflected signal.

Abstract: This invention provides a method for commissioning and upgrading an optical ring network using its internal amplifiers as Automatic Spontaneous Emission sources of light that are used in making measurements. A modular segmented approach is adopted and the network is commissioned segment by segment. A flexible method is used for upgrading a commissioned network by adding or deleting a node or changing the internal configuration of a node. The method uses techniques for the correction of the Optical Signal to Noise Ratio induced error as well as the Spectral Filtering Error during the loss computation required for adjusting the gains of the amplifiers at each network node to an appropriate value. Since the method does not require an external laser source that needs to be moved manually from node to node it greatly reduces the commissioning time. Since it uses only the components of the network itself and does not deploy any additional device it also leads to a significant saving in cost.

Abstract: A plurality of microwave signals are converted into optical signals which are directed against an optically reflective surface, whereby the optical signals reflected off of the optically reflective surface are received and converted into microwave signals, which are passed through a Fourier Transformer for extracting information of interest.

Abstract: In optical communication systems, an optical signal which is modulated with a data signal is transmitted from an optical transmitter, and is launched into a fiber-optic transmission link. The present invention provides a method and an apparatus for the measurement of the distribution of the reflectivity along an optical transmission line implemented by using the signal processing based on the cross-correlation function between the data signal with which the optical transmitter is modulated and the back-reflected signal returned to the optical transmitter to provide the in-service monitoring of the fiber-optic transmission link.

Abstract: An optical line monitoring apparatus, including: a group information recording portion which records group information about to which splitter respective terminators are connected; a normal information recording portion which records intensities of reflected lights from a plurality of terminators in a state in which a failure is not occurring in optical lines; a monitored information recording portion which records intensities of reflected lights from the plurality of terminators in failure monitoring time; an attenuation amount determination portion which determines a terminator the reflected light intensity of which is attenuated compared with the corresponding reflected light intensity in normal information; and a control portion which determines, if the intensities of the reflected lights of all the terminators connected to the same splitter are attenuated by the same value, that a failure has occurred between the test apparatus and the splitter to which all the terminators are connected.

Abstract: A dual structure for a multiplexing section extended to an OSU is obtained without adding a dynamic function, such as an optical switch, to a W-MULDEM. The W-MULDEM of an optical wavelength division multiplexing access system divides, among ports corresponding to the individual ONUs, downstream optical signals having wavelengths ?d1 to ?dn, which are received along a current-use optical fiber, or downstream optical signals having wavelengths ?d1+?? to ?dn+??, which are received along a redundant optical fiber. The W-MULDEM also multiplexes, for the port that corresponds to the current-use optical fiber or the redundant optical fiber, upstream optical signals having wavelengths ?u1 to ?un or wavelengths ?u1+?? to ?un+??, which are received along optical fibers corresponding to the ONUs. A wavelength difference between the downstream optical signal and the upstream optical signal that are consonant with each ONU is defined as an integer times the FSR of an AWG.

Abstract: There is provided in a telecommunications network comprising an optical fiber cable, and an optical component connected to a first point of the optical fiber cable, with an optical time domain reflectometer (OTDR) connected to a second point of the optical fiber cable so that it can emit OTDR signals along the optical fiber cable towards the optical component, a method of preventing OTDR signals from being applied to the optical component, comprising introducing one or more optical signals into the optical fiber cable at the first point thereof using the optical fiber cable to carry the optical signals to the second point thereof, and configuring the OTDR to detect the or each optical signal from the optical fiber cable and to prevent emission of OTDR signals at any time during which detection of an optical signal occurs. The optical component may comprise, for example, an optical receiver which may introduce the optical signals into the optical fiber cable.

Abstract: A fault localization apparatus for an optical line in a wavelength division multiplexed passive optical network is disclosed. The apparatus can detect light loss and fault positions as a channel exhibiting an abnormal receiving state of signals received by each of the upstream receivers is checked, and a monitoring optical signal is used, in which the monitoring optical signal is generated as a pulse is inputted to a light source of the downstream transmitter corresponding to the channel showing such an abnormal receiving state. The apparatus according to the present invention can detect fault positions of optical lines between the central office and the remote nodes and between the remote nodes and the optical network units, since the light source of downstream channel in which faults occur is used as a monitoring light source. The apparatus according to the present invention can be cost-effectively implemented.

Abstract: In accordance with the teachings of the present invention, a method and apparatus is presented for troubleshooting a fiber-optic cable. A fiber-optic, cable-troubleshooting system includes an integrated Optical Time Domain Reflectometer (OTDR) for generating an optical distance to a fault and a cable-locating module for presenting a tone on a fiber-optic cable. A technician uses the tone to locate the fiber-optic cable and the optical distance to locate the fault in the fiber-optic cable.

Abstract: A distributed fiber optic sensor simultaneously interrogates the sensing fiber with two counter propagating light beams. One beam is set to a constant frequency. The second beam is modified to contain a “comb” of frequencies, with each frequency component in the comb offset by a predetermined amount. Each of the frequency components in the comb, herein referred to as teeth, is able to interact with the counter-propagating beam through the Brillouin scattering process. With proper selection of the comb characteristics such as the number of teeth, the frequency spacing of teeth, the spectral width of teeth, and the relative amplitude of the teeth, a representation of the Brillouin spectrum at each point in the fiber can be obtained simultaneously with a single pass through the fiber.

Abstract: The subassembly includes a laser for emitting signals towards fibers to be monitored, a passive alignment carrier, a first photodetector for monitoring reflected laser signals from the fibers, a second photodetector for monitoring laser output power, and an optical fiber. The laser is disposed within the passive alignment carrier. The optical fiber is embedded in the passive alignment carrier, and has an angled fiber facet. The laser emits signals toward and through the angled fiber facet, whereby a portion of the laser signal illuminates the second photodetector, and another portion illuminates the fibers that are being monitored and reflects back to the first photodetector such that faults on the fibers can be detected.

Abstract: A system and method for performing an in-service optical time domain reflectometry (OTDR) and/or insertion loss (IL) measurement(s) using the same wavelength as the data traffic for point-to-point or point-to-multipoint optical fiber networks. The OTDR or IL sessions are multiplexed in accordance with the network protocol in use to avoid any distortion of data transmissions.

Abstract: In an optical transmission link having discrete optical reflection sources that cause multi path interference (MPI) and optical return loss (ORL), a method determines how to reduce to beneath a predetermined threshold, a predetermined phenomenon (MPI or ORL or a composite of the two). The method involves (408/428/458) measuring link parameters of the optical transmission link using an optical reflectometry technique, (410/430/460) calculating a level of the predetermined phenomenon based on the link parameters, and (416/436/466) simulating replacement of a number of the reflection sources until the calculated level of the predetermined phenomenon is reduced to less than the predetermined threshold. The method may be performed within a portable optical reflectometry device to facilitate field simulations.

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: A security system for controlling access to an enclosed conduit along which runs fiber optic cable, the conduit having a cover for access to the cable, the system having a communications receiver and a modulator responsive to an output of the receiver for coupling non-intrusively to the fiber optic cable adjacent the cover, the communications receiver being responsive to the presence or absence of an access authorization signal from an operator to cause the modulator to introduce a signal to the fiber optic cable indicative of the authorization status.

Abstract: This invention provides a method for commissioning an optical network using internal Automatic Spontaneous Emission (ASE) light inherently present in the optical network as a light source (the ASE light source) for measuring losses inside and between nodes in the network. A modular segmented approach is adopted and the network is commissioned segment by segment. The method uses techniques for the correction of the Optical Signal to Noise Ratio induced error as well as the Spectral Filtering Error during the loss computation required for adjusting the gains of the amplifiers at each network node to an appropriate value. Since the method does not require an external laser source that needs to be moved manually from node to node, it greatly reduces the commissioning time. Since it uses only the existing components of the network nodes it also leads to a significant saving in cost.

Abstract: An optical transmitter transmits a light which alternately exhibits a spectrum line width wider than a Brillouin bandwidth and a spectrum line width narrower than the Brillouin bandwidth. The transmitted light is provided to an optical transmission line so that the transmitted light travels in the transmission line and thereby causes returning light to be generated in the transmission line. An optical detecting section detects the returning light. Disconnection of the transmission line is detected from the detected returning light.

Abstract: A transmission system is provided that recognizes occurrence of a fault efficiently so that the workability and quality of service can be improved. An optical amplifier part amplifies an optical main signal. A fault occurrence recognizing part detects a pump light used for an opposing device via an optical fiber transmission line to which an optical main signal is sent by the repeater. If the pump light is not detected, the fault occurrence recognizing part recognizes occurrence of a fault. A light cutoff control part stops the optical amplifying part outputting an amplified signal so that the light cutoff control in only one of two directions is performed when a fault occurs.

Abstract: An optical fiber is wound onto an exterior surface of a composite structure in a two-dimensional pattern and adhered thereto to detect damage to the structure caused by impacts to or handling of the composite structure.

Abstract: The present invention implements open fiber control in an optical transceiver. During normal operation, the transceiver transmits signals through a connection to an optical network. When the connection is intact, the total power transmitted can be greater than the eye-safety limit. When the connection breaks, the transceiver detects the loss of signal and disables transmissions over all channels except for one. The transceiver continues transmission on the single enabled channel at an eye-safe level. When the connection is fixed and a signal reappears, the transceiver detects the signal reappearance and re-enables all channels that had previously been disabled. By allowing the transceiver to transmit with greater optical power when the connection is intact, an increased data rate and longer transmission distances can be achieved. At the same time, safety is preserved, because transmissions drop to acceptable power levels whenever a break is detected.

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.