Abstract: Systems and methods for detecting fiber port availability in a fiber distribution hub and generating fiber port recommendations are presented. An exemplary method may include detecting, based at least on a fiber distribution record, one or more candidate ports in the fiber distribution hub; transmitting a first indication of a first selected port of the one or more candidate ports to a computing device; detecting, after transmitting the indication of the first selected port and in real time, that a termination unit associated with the fiber distribution hub has been disconnected; automatically updating the fiber distribution record such that the fiber distribution record is representative of an association between the termination unit and the first selected port; and generating, based on detecting that the termination unit has been disconnected, a second indication of a second selected port of the one or more candidate ports.

Abstract: A method of identifying a fault in an optical link comprises continually storing samples of a signal that represents a power of an optical signal received over the optical link. When a fault is detected on said optical link, at least one stored series of samples of the signal is retrieved. The method then comprises performing a classification on the retrieved series of samples, in order to classify the series of samples as resulting from one of a plurality of predefined faults.

Abstract: Systems and methods for characterizing an optical fiber performed in part by an optical node (12) in an optical line system (10) include performing one or more measurements to characterize the optical fiber (16, 18) with one or more components (50, 52) at the optical node (12), wherein the one or more components (50, 52) perform functions during operation of the optical node (12) and are reconfigured to perform the one or measurements independent of the functions; and configuring the optical node (12) for communication over the optical fiber (16, 18) based on the one or more measurements. The one or more components can include any of an Optical Service Channel (OSC), an Optical Time Domain Reflectometer (OTDR), and an optical amplifier. The configuring can include setting a launch power into the optical fiber based on the one or more measurements.

Abstract: Aspects of the present disclosure describe systems, methods and structures and applications of optical fiber sensing. Of significance, systems, methods, and structures according to aspects of the present disclosure may reuse and/or retrofit/upgrade existing optical fiber cables as part of optical fiber sensing that may find important societal application including intrusion detection, road traffic monitoring and infrastructure health monitoring. Combining such optical fiber sensing with artificial intelligence (AI) further enables powerful applications at low(er) cost.

Abstract: A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

Abstract: Systems and methods for performing connectivity verification testing and topology discovery in a reconfigurable optical add/drop multiplexer (ROADM) are provided. The ROADM can include a ROADM block having a plurality of internal ports connected to a fiber shuffle via respective optical fibers. The ROADM block includes a test signal transmitter configured to inject an outgoing test signal having a unique signature into each internal port. The outgoing test signals are out-of-band of optical data signals traversing the ROADM. The ROADM block includes a test signal monitor configured to monitor for incoming test signals at each of the internal ports. The test signal monitor is configured to validate, based on a signature of an incoming test signal received at an internal port of the ROADM block, whether a valid connection exists between the internal port and an internal port of a second ROADM block.

Abstract: A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

Abstract: A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

Abstract: Methods, optical transmitters and a system of optical transmitters for transmitting data over and monitoring a fiber cable. A method performed by an optical transmitter for transmitting data over and monitoring of a fiber cable comprises generating at least a first optical carrier and a second optical carrier at a same optical frequency, generating an electromagnetic monitoring signal, modulating the first optical carrier with the generated electromagnetic monitoring data signal to create an optical monitoring signal, and modulating the second optical carrier with a generated electromagnetic data signal to create an optical data signal. The method further comprises combining the optical monitoring signal and the optical data signal in orthogonal polarization modes, transmitting the combined optical monitoring signal and the optical data signal over the fiber cable to be monitored, and monitoring the fiber cable by detecting the optical monitoring signal being backscattered from the fiber cable.

Abstract: A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

Abstract: A programming device is provided that programs cards, such as payment cards, with data, such as personal data, using light transmitters and receivers. For example, an infrared transmitter may be provided to program personal data (e.g., a customer's credit card number) into a card wirelessly. In doing so, the card may be, for example, completely laminated such that there are no exposed electronic components on the exterior surface of the card and be programmed via light. The programming device may shield the programming components to block ambient light from interacting with those programming components during programming. A conveyor may be utilized to align multiple cards with a programming device to allow assembly-line style programming of the cards.

Abstract: Raman amplifier systems and methods with an integrated Optical Time Domain Reflectometer (OTDR) for integrated testing functionality include an amplifier system, an OTDR and telemetry subsystem, and a method of operation. The OTDR and telemetry subsystem is configured to operate in an OTDR mode when coupled to a line in port and to operate in a telemetry mode when coupled to a line out port. The OTDR and telemetry subsystem enables on-demand fiber testing while also operating as a telemetry channel that is both a redundant optical service channel (OSC) and provides a mechanism to monitor Raman gain over time. The OTDR and telemetry subsystem minimizes cost and space by sharing major optical and electrical components between the integrated OTDR and other functions on the Raman amplifier.

Abstract: An apparatus and method for fault indication and localization in a Passive Optical Network (PON) comprising a multistage power splitter (100, 200, 300) with at least one 1:N splitter (120, 221, 222, 321, 322) followed by N items of 2:M splitters (131, 132, 231-233, 331-336), wherein N and M are integers greater than 1. The apparatus also comprises an Optical Time Domain Reflectometry (OTDR) device (110, 210, 310) capable of inserting an OTDR signal into the power splitter (100, 200, 300), and adapted to insert the OTDR signal between the first stage of the at least one 1:N splitter (120, 221, 222, 321, 322) and the second N items of 2:M splitters (131, 132, 231-233, 331-336).

Abstract: An optical transceiver has a communications mode and an optical time domain reflectometer (OTDR) mode. The transceiver comprises a transmitter channel and a receiver channel operable, in the communications mode, to respectively transmit and receive communications signals through respective external optical fibers. The transceiver also comprises a guide arrangement for guiding, in the OTDR mode, a reflected OTDR signal along a path from the transmitter channel into the receiver channel. A method of obtaining test data for an optical fiber in an optical data communications subsystem is also disclosed.

Abstract: A fiber network events measurement apparatus has a laser module alternately generating a pulse signal detecting beam and an FMCW detecting beam. The beams are sent to the fiber network route through a directional coupler. A photo detector receives feedback energy of the beams transmitting in the fiber network route and converts the feedback energy into electronic signals. A mixer uses a frequency difference calculation to obtain a comparison result according to an original and a reflected FMCW signal. The electronic signal is converted into a digital signal by an A/D converter. A signal control unit then obtains a compound trace result including information of characteristic trace and event positions. The compound trace result shows a fiber characteristic trace and event position trace for measuring the fiber network routes.

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 and method for monitoring an optical line is provided. The optical line monitoring apparatus may include a comparison unit to extract first identification information about an optical network terminal (ONT) from reflected data that is reflected and received from the optical line, and to compare the extracted first identification information to predetermined second identification information about the ONT, and a processor to analyze a state of the optical line using the reflected data when the first identification information is identical to the second identification information.

Abstract: An optical network (1) comprising an optical network element (10) comprising a first optical transmitter (14), a first controller (16), a first optical receiver and a second optical receiver and a second optical network element (12). There is provided a transmission path (30) between said first optical network element and said second optical network element. Said first optical transmitter is arranged to generate and transmit a first optical signal. Said first controller is arranged to control said first optical transmitter to generate and transmit said first optical signal at a wavelength selected from a predetermined plurality of wavelengths. Said first optical receiver is arranged to detect a backscatter portion of said first optical signal returned to said first optical network element along said transmission path by distributing scattering.

Abstract: Methods and devices provide for storing historical data that includes interference values mapped to at least one of bend radii values, lifetime values, or failure rate values of optical fibers; transmitting an optical signal, via a test system, toward the optical fiber under test; setting a polarization state of the optical signal before the optical signal propagates through the optical fiber under test; setting a polarization state of a reflected optical signal that has propagated through the optical fiber under test in a manner that causes a minimum interference or a maximum interference; measuring instances of power of the reflected optical signal; and outputting a result that includes at least one of a bend radius value, a lifetime value, or a failure rate that applies to the optical fiber under test based on the measured instances of power and the historical data.

Abstract: A manner of providing for testing of access fibers in a PON (passive optical network) using OTDR (optical time-domain reflectometry). According to the invention, a PON includes an optical splitter module having one or more optical couplers that combines downstream light from 1×N optical splitter directing the output of an OLT (optical line terminal) and a cyclic AWG (arrayed waveguide grating) for transmission toward one or more ONUs (optical network units). The splitter module is preferably formed on a single semiconductor chip, such as a PIC (photonic integrated circuit) chip and may reside in an outside plant of the PON.

Abstract: An optical transceiver having an integrated optical time domain reflectometer monitoring unit and methods for using the same are disclosed. The disclosure relates to an optical transceiver comprising an optical device comprising a wavelength division multiplexing system (WDM), a data signal driver, a data signal limiting amplifier, and an optical time domain reflectometer (OTDR) data processing module. Furthermore, the optical transceiver is particularly advantageous in an optical line terminal (OLT) and/or a passive optical network (PON). The integrated OTDR data processing module can protect the optical transceiver, ensure successful monitoring data, simplify network wiring and decrease system and network costs by decreasing the number of OTDR modules and WDM units.

Abstract: A system for supervision of a passive optical network includes an OTDR device, generating N+1 OTDR signals of wavelengths ?U-?N, and transmitting the signals towards ONUs. The system includes a splitter having N output branches. An input of the splitter is connected to the output of the OTDR device and the output branches of the splitter are indirectly connected to the ONUs. The splitter splits the OTDR signals and forwards them towards the ONUs. The system includes a wavelength isolator having inputs connected to the splitter output branches. The wavelength isolator isolates, on individual inputs, one predetermined wavelength of the received OTDR signals per individual input, where two inputs of the wavelength isolator do not isolate the same wavelength, and forwards, from each of the inputs of the wavelength isolator, the OTDR signals to associated outputs towards the ONUs connected to the wavelength isolator by individual fibre links.

Abstract: A method for detecting branch fibers is provided, which includes: sending test signals to a plurality of branch fibers, where the test signals are added at ports of the optical splitting module with identification information for identifying branch fibers connected to the ports and receiving a reflection signal added with the identification information of a detected branch fiber, identifying the detected branch fiber corresponding to the reflection signal through detecting the identification information added to the reflection information, and obtaining channel characteristics of the detected branch fiber according to the reflection signal. Further, a system and an apparatus for detecting branch fibers are 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: In a first aspect, the method and apparatus of the present disclosure can be used to periodically and/or intermittently place one or more ONUs attached to a PON in a power savings mode so that an OTDR test can be performed. While in the power savings mode, the ONUs temporarily suspend their transmitter function and power down their upstream lasers. In a second aspect, the method and apparatus of the present disclosure can be used to coordinate the performance of OTDR during one or more periodic or intermittent discovery slots used to detect and register ONUs recently connected to the PON. Because new ONUs are infrequently connected to the PON and ONUs already registered are not permitted to transmit during the discovery windows, OTDR can be performed during these windows without impacting, to a great degree, the normal operation of the PON.

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: A distributed optical fiber sound wave detection device is provided with an optical pulse emission unit that causes an optical pulse to be incident into the optical fiber, and a Rayleigh scattered light reception unit that receives Rayleigh scattered light produced inside the optical fiber. The optical pulse emission unit outputs the optical pulse that is modulated using a code sequence which has a predetermined length and by which the optical pulse is divided into a plurality of cells. The Rayleigh scattered light reception unit includes a phase variation derivation unit that performs demodulation corresponding to the modulation in the optical pulse emission unit on the Rayleigh scattered light and determines a phase variation thereof from the demodulated Rayleigh scattered light, and a sound wave detection unit that determines a sound wave that has struck the optical fiber from the phase variation determined by the phase variation derivation unit.

Abstract: The present invention relates to the field of communication transmission, and in particular, to a method for generating a probe pulse and a coherent optical time domain reflectometer. The coherent optical time domain reflectometer includes: a control unit, configured to generate a first pulse signal and a second pulse signal which have a same period T, where the second pulse signal lags behind the first pulse signal, and T satisfies T?t+2L/C; a driving unit, configured to generate a frequency change driving signal according to the first pulse signal; a continuous light laser device, configured to generate, as driven by the frequency change driving signal, continuous light having a changing frequency and an unchanging frequency spectrum width; and a probe pulse generating unit, configured to modulate the continuous light according to the second pulse signal to generate a probe pulse.

Abstract: A Wavelength Adaptation Module and a method therein for adapting an Optical Time Domain Reflectometry, OTDR, signal for supervision of Optical Network Terminals, ONTs, in a Passive Optical Network, PON, are provided. The wavelength of the OTDR signal is adapted to have a selected wavelength to enable a splitter in a remote node to forward the OTDR signal to a dedicated group of ONTs in the PON, thereby supervising the fibre links between the remote node and the dedicated group of ONTs. Likewise, a remote node and a method therein for receiving an OTDR signal having a pre-selected wavelength from the Wavelength Adaptation Module and for outputting the OTDR signal to a dedicated group of ONTs with regards to the pre-selected wavelength of the received OTDR signal are provided.

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: A method for allocating faults in a passive optical network (PON) by placing a number of passive unique optical correlators in a number of respective diagnostic points of the PON, each of the passive unique optical correlators being responsive to an optical diagnostic signal by returning a predetermined unique matching signal; by further transmitting the diagnostic optical signal in the PON towards the diagnostic points to receive upstream response signals from the correlators. Upon detecting presence or absence, in the received response signals, of a predetermined unique matching signal expected from a specific optical correlator, judging about a fault in proximity of the respective specific diagnostic point.

Abstract: There are provided a device for monitoring an optical link fault and a method thereof. According to an embodiment of the invention, the device for monitoring an optical link fault and the method thereof apply an optical link fault monitoring signal to an optical link and precisely identify a type of the fault using waveforms of a reflected signal returned from the optical link or a wavelength dependence of reflected signal intensity.

Abstract: A method includes applying pulsed light to a first end of an optical fiber from an optical fault locator during a first distance test. The method includes determining an estimated distance to a fault based on the pulsed light. The method includes sending information indicative of the estimated distance to a remote device. The method also includes applying first visible light from the optical fault locator to the first end of the optical fiber to facilitate identification of the fault at a first site that is remote from the first end of the optical fiber.

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.

Abstract: Problems of excessive fading in systems for monitoring single-mode optical fiber for physical disturbances are addressed by launching into the fiber polarized light having at least two different predetermined launch states of polarization whose respective Stokes vectors are linearly-independent of each other; downstream from the first location, receiving the light from the fiber; analyzing the received light using polarization state analyzer means having at least two different analyzer states of polarization that are characterized by respective Stokes vectors that are linearly-independent of each other and detecting the analyzed light to provide corresponding detection signals; deriving from the detection signals measures of changes in polarization transformation properties of the fiber between different times that are substantially independent of said launch states and said detection states; and, on the basis of predefined acceptable physical disturbance criteria determining whether or not the measures are i

Abstract: A multi-function optical tool may be used for example for built-in fault detection and transceiver source characterization in local optical communication networks. A single device provides swept-heterodyne optical spectrum analysis (SHOSA) and optical frequency-domain reflectometry (OFDR) in an efficient, low-cost package by utilizing a common interrogation laser source, common optical components, and common, low-bandwidth acquisition hardware. The technology provides significant cost, space, and labor savings for network maintainers and technicians.

Abstract: A wavelength shifter module and a method therein for tuning an OTDR signal to at least one pre-selected wavelength in a passive optical network (PON). The wavelength of the OTDR signal is shifted to a pre-selected wavelength to enable a remote node in the optical distribution network ODN of the PON to forward the OTDR signal to a specific drop section in the ODN. The invention also includes a remote node and a method in a remote node for receiving a wavelength shifted OTDR signal having a preselected wavelength and outputting the wavelength shifted OTDR signal to a specific drop section. Furthermore, the invention involves a method for determining the location of a fault section in a drop section.

Abstract: A client unit and a method are provided performing fault analysis in a Passive Optical Network, PON, by using Optical Time Domain Reflectometry, OTDR. The method comprises triggering a new OTDR measurement, wherein a previous reference measurement has been made indicating an original state of the PON. The method further comprises inserting an OTDR measurement signal into a multistage splitter before a last splitter stage of the multistage splitter, and wherein the last splitter stage is of ratio 2:N; and obtaining at least one new event location based on the OTDR measurement signal. Further, the method comprises calculating a fault magnitude at a given location by subtracting an event magnitude obtained from the new OTDR measurement from the reference OTDR measurement and taking into account the number of drop links connected to the last splitter stage in the reference measurement and the new measurement. Thereby, determination of position and severity of the fault locations is enabled.

Abstract: The present invention discloses a Wavelength Division Multiplexing Filter which can satisfy coexistence requirements of different PON systems and an optical line detecting system.

Abstract: An active network monitoring system for detecting an abnormality at a position between a communication office and a client includes a first monitoring module disposed on the communication office, a second monitoring module disposed on the client and an optical splitter. The first monitoring module has a first processor and a first laser diode. The second monitoring module has a second processor and a second laser diode. The first processor sends a digital signal to the first laser diode. The first laser diode modulates the digital signal into an optical signal and sends the optical signal to the second monitoring module via the optical splitter. The second laser diode converts the optical signal back to the digital signal, and sends the digital signal to the second processor to generate an identification signal of the client. The identification signal is transmitted to the communication office via the second laser diode.

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 technique for detecting a fiber fault in a WDM optical access network includes launching a test signal into a fiber trunk line linking a central office (“CO”) to a remote node (“RN”) of the WDM optical access network. The test signal is generated by an optical time domain reflectometry unit to simultaneously fault test fiber access lines linking the RN to customer premises. The test signal is separated from downstream WDM signals at the RN. The test signal is power split at the RN into a plurality of access line test signals. The access line test signals are each recombined with a corresponding one of the downstream WDM signals onto a corresponding one of the fiber access lines. Test signal reflections are received at the CO from the fiber access lines as a reflection signature and analyzed to identify a location of the fiber fault.

Abstract: A data processing device is connectable to a communication network and operable to receive data associated with an attenuation characteristic of a transmission line of a cable in a cable communication subsystem, the subsystem comprising a transmitter and/or receiver coupled to the cable. The data processing device is responsive to the received data to initiate a security procedure.

Abstract: A particular method includes applying light pulses to an optical fiber and receiving backscattered light at a phase-sensitive optical time domain reflectometry (OTDR) device. The backscattered light includes portions of the applied light pulses that are backscattered by the optical fiber. The method also includes determining a difference between the backscattered light and a backscatter pattern associated with the optical fiber. The method also includes determining a communication signal encoded in the backscattered light based on the difference, where the communication signal is encoded in the backscattered light responsive to mechanical waves applied to the optical fiber at a location remote from the phase-sensitive OTDR device.

Abstract: A detecting method, an apparatus, and a system in an Optical Distribution Network (ODN) are provided. The method includes: an Optical Line Termination (OLT) reserves a test window, and an Optical Network Unit (ONU) stops sending an uplink signal in the test window, the OLT emits a downlink test signal having a wavelength the same as that of the uplink signal in the test window, the OLT receives backward signals of the downlink test signal, in which the backward signals include a backward scattered signal and a backward reflected signal, processes the backward signals, and obtains state information of the ODN according to the backward signals. The method does not need to add other hardware, and the downlink signal is sent normally in the downlink. The implementation is low in the cost and easy in the technology.

Abstract: A reconfigurable polarity detachable connector assembly includes a housing defining two accommodation channels and providing a springy protruding member at a top side, two mating simplex connectors respectively detachably mounted in the accommodation channels of the housing, a fiber optic cable fastened to the housing with two optical fiber cores thereof respectively inserted into respective calibration support rods of the mating simplex connectors, and a sliding cap slidably coupled to the housing. The sliding cap is unlocked and can be moved backwardly relative to the housing to expose the optical fiber cores of the fiber optic cable to the outside of the housing for allowing position exchange between the two mating simplex connectors after the user presses the springy protruding member.

Abstract: The present invention is related to a front-end circuit for an optical communication system including a laser module arranged for transmitting bursts of data signals over an optical network and a driving circuit for providing the bursts of data signals to the laser module. The front-end circuit further includes receiver means in connection with said laser module and arranged for receiving from the optical network optical echo signals. The laser module includes a laser diode arranged for transmitting the bursts of data signals. The driving circuit is arranged for setting a disabling signal for stopping the laser diode from transmitting bursts of the data signals. Fiber-related information can be extracted from the echo signals, such as distance-resolved optical fiber reflections and fiber attenuation.

Abstract: Implementations of techniques and systems are disclosed for detecting a fiber fault in a point-to-point optical access network based on optical time domain reflectometry (“OTDR”) measurements. The techniques include identifying loss of service between a central office (“CO”) and a given optical network unit (“ONU”) of a plurality of ONUs. In response to the identifying the loss of service, configuring a test signal distribution unit to optically couple an OTDR unit to a selected subset of the point-to-point fiber links which includes the given ONU. An optical test signal is launched from the OTDR unit into the selected subset of the point-to-point fiber links via the test signal distribution unit. Test signal reflections are received from each of the point-to-point fiber links within the selected subset as a reflection signature, which is analyzed to identify a location of the fiber fault.

Abstract: An OTDR device and method for characterizing one or more events in an optical fiber link are provided. A plurality of light acquisitions is performed. For each light acquisition, test light pulses are propagated in the optical fiber link and the corresponding return light signals from the optical fiber link are detected. The light acquisitions are performed under different acquisition conditions, for example using different pulsewidths or wavelengths. Parameters characterizing the event are derived using the detected return signal from at least two of the plurality of light acquisitions.

Abstract: A method of monitoring (200) an optical fiber comprises modulating (210) an optical signal with a traffic signal; modulating (220) the optical signal with an incoherent optical frequency domain reflectometry, IOFDR, test signal; transmitting (230) the doubly modulated optical signal onto an optical fiber at a first end of the fiber; detecting (240) scattered radiation output from the first end of the fiber; and analyzing (250) the detected scattered radiation using incoherent optical frequency domain reflectometry to determine a distance to a break in the optical fiber. Apparatus suitable for carrying out the method is also described, as well as an optical communications network employing the method.