The invention relates to a device and a method performed by the device of monitoring an optical fibre link. The method provided for monitoring an optical fibre link comprises generating a monitoring signal used for monitoring the optical fibre link, combining the generated monitoring signal with a data signal to be transmitted over the optical fibre link, detecting backscattering of the monitoring signal from the optical fibre link, comparing the detected backscattered monitoring signal with an estimated monitoring signal backscattered along the optical fibre link, and determining, based on the comparison, at least one location along the optical fibre link where the monitoring signal is backscattered, and signal loss caused by the backscattering.

A data communication network includes a network node and a processor. The network node includes an optical link and a reflectometry analyzer to provide a plurality of reflectometry results, each reflectometry result providing a characterization of physical and operational properties of the optical link at the time of the reflectometry result. The processor receives a first set of the reflectometry results, and calculates a federated fingerprint of the physical and operational properties of the optical link based on the plurality of fingerprints in first set of the reflectometry results. The federated fingerprint is a combination of fingerprints from every section of the optical link. The processor receives a second set of the reflectometry results, and compares each of a plurality of fingerprints in the second set of reflectometry results with a respective corresponding fingerprint in the federated fingerprint. The processor determines whether a physical tampering of the optical link has occurred based upon the comparison.

Systems, methods, and non-transitory computer readable media are configured to determine an optical length of an event in a cable. A physical length of the event in the cable can be determined based on a correlation between optical lengths and physical lengths in the cable. A geographic location of the event can be provided based on the physical length of the event.

One embodiment described herein provides a system for distributed fiber sensing. The system can include a plurality of network elements (NEs) in an optical transport network (OTN) and a control-and-management module coupled to the NEs. A respective network element (NE) can include a first wavelength coupler configured to separate an optical supervisory channel (OSC) signal from a data-carrying signal received from a fiber span, a polarization-measurement unit configured to perform a polarization measurement on the OSC signal, and a transmitter configured to transmit an outcome of the polarization measurement to the control-and-management module, thereby facilitating distributed fiber sensing based on the outcome of the polarization measurement.

This application discloses a submarine cable fault determining method and apparatus for realizing detecting whether a fault occurs to a submarine cable, without depending on TTE. The submarine cable fault determining method includes: receiving, by a network management system, first detection information from a first device during a first preset time, and receiving second detection information from a second device during a second preset time, where the second detection information is used to indicate whether the second device receives a first heartbeat signal from the first device through a submarine cable, and the first detection information is used to indicate whether the first device receives a second heartbeat signal from the second device through the submarine cable; and determining, by the network management system based on the first detection information and the second detection information, whether a fault occurs to the submarine cable between the first device and the second device.

Using pump-probe measurements on multi-span optical links may result in the determination of one or more of the following: 1) wavelength-dependent power profile and gain evolution along the optical link; 2) wavelength-dependent dispersion map; and 3) location of regions of high polarization-dependent loss (PDL) and polarization-mode dispersion (PMD). Such measurements may be a useful diagnostic for maintenance and upgrade activities on deployed cables as well as for commissioning new cables.

In one embodiment, a system for analyzing optical networks includes a network analyzer optically coupled to a fiber optic network. The network analyzer may transmit a test signal to the fiber optic network, receive a reflected signal in response to transmitting the test signal, wherein the reflected signal is generated in response to the test signal interacting with a defect of the fiber optic network. The analyzer may then analyze a power of the reflected signal, wherein the power of the reflected signal corresponds to the defect in the fiber optic network, calculate a transmit time of the reflected signal, wherein the transmit time corresponds a location of the defect in the fiber optic network, identify a component of the fiber optic network corresponding to the defect and the location of the defect in the fiber optic network, and generate a maintenance report based on the analyzed reflected signal.

An optical network system includes: a plurality of optical transmission devices, each includes a transmitting unit configured to superimpose, on a main signal to be transmitted, a monitoring signal of a different wavelength from wavelengths of other optical transmission devices, the wavelength differing from wavelengths for other optical transmission devices in the optical network system, and an extraction unit configured to extract monitoring signals from main signals received from the other optical transmission devices, wherein a failure occurrence section where a communication failure occurs is determined, based on the monitoring signals extracted by the extraction unit, among transmission sections between the respective optical transmission devices.

A device may receive health information associated with a network circuit included in an optical network. The device may determine, based on the health information and network circuit information associated with the network circuit, that the network circuit is experiencing a health issue. The device may identify a diagnostic technique to be applied to the network circuit based on determining that the network circuit is experiencing the health issue. The device may automatically and iteratively apply the identified diagnostic technique to the network circuit in order to identify a fault location. The device may determine a corrective action, associated with the network circuit, based on the fault location and the health issue. The device may provide information associated with the corrective action to cause the corrective action to be taken.

A line monitoring system may include a laser source to launch a probe signal over a first bandwidth, a polarization maintaining tap to receive and split the probe signal, into a first portion and a second portion, a polarization rotator to receive the first portion and send the first portion to a transmission system, a return tap to receive the second portion and to receive a return signal from the transmission system, wherein the return signal being derived from the first portion, a photodetector coupled to receive an interference signal from the return tap, wherein the interference signal is generated by a mixing the return signal and the second portion, where the photodetector is arranged to output a power signal based upon the interference signal, and a power measurement system to measure the power signal at a given measurement frequency over a second bandwidth, comparable to the first bandwidth.