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.

An excitation light source device includes: an excitation light source to generate the Raman excitation light; a light source controller to control an intensity of the Raman excitation light; an amplified spontaneous emission noise measurer to measure an intensity of amplified spontaneous emission noise caused by the Raman excitation light; and a transmission line abnormality analyzer to detect abnormality in the transmission line on a basis of a control state of the light source controller and a measurement result of the amplified spontaneous emission noise measurer. In a state where the abnormality is not detected, the light source controller controls the intensity of the Raman excitation light to gradually increase to a set value. In a state where the abnormality is detected, the light source controller controls the excitation light source to stop or reduce generation of the Raman excitation light.

A method and an apparatus for predicting a fault of an optical circuit includes determining a classification threshold of an operating parameter based on a classification sample set corresponding to the operating parameter of optical circuit and predicting, based on comparison results between the classification threshold and a plurality of measured values in a sequence, whether a fault occurs in the future on the optical circuit corresponding to the sequence.

A wavelength-tunable optical filter control apparatus in an optical access system that uses wavelength-multiplexed optical signal of a plurality of wavelength channels includes a wavelength-tunable optical filter configured to pass an optical signal of a specific wavelength channel among the plurality of wavelength channels; a light receiving element configured to convert the optical signal that has passed through the wavelength-tunable optical filter into an electrical signal; a signal quality determining unit configured to determine a quality of the electrical signal; and a wavelength-tunable optical filter control unit configured to acquire a light intensity of the electrical signal and control a wavelength of the wavelength-tunable optical filter based on the acquired light intensity and a determination result of the quality of the electrical signal.

A multiplexed sensor system includes a control unit in communication with a plurality of sensors. A plurality of optic fibers defines a communication path between the plurality of sensors and the control unit. A multiplexing portion communicates with a plurality of sensors along a common one of the plurality of optic fibers and a protected channel through which at least a portion of the optic fibers are routed. The protected channel at least partially surrounds the optic fibers and shields the optic fibers from an environment outside the protected channel. A cooling flow is provided through the protective channel for minimizing temperature fluctuations within the protective channel. A method is also disclosed.

An optical transceiver, for receiving an optical signal on which a monitor signal is superimposed, includes: an extractor configured to extract the monitor signal from the optical signal received; and a reception processor configured to reproduce a monitor data from the monitor signal extracted by the extractor.

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.

Systems and methods of estimating a distance to a cause of a micro-reflection in a CATV network.

An optical signal-to-noise ratio (OSNR) measuring device includes a processor, wherein the processor executes a process. The process includes: converting an optical signal to an electrical signal; first acquiring a signal intensity from the electrical signal; second acquiring a noise intensity of a predetermined frequency band from the electrical signal; performing a digital conversion on the noise intensity; and computing an OSNR of the optical signal based on the signal intensity and the converted noise intensity. The predetermined frequency band is a frequency band including a folding noise that occurs when the digital conversion is performed.

A method of localizing a defect location and a method of identifying a cause of a defect in an optical transport network (OTN). The method of localizing a defect location in an OTN includes generating tandem connection monitoring (TCM) coordinates consisting of a TCM level and trail information of an optical data unit (ODU) based on a relationship between an OTN line card (LC) and the ODU in the OTN, localizing the defect location in the OTN by converting the TCM level to a segment on the TCM coordinates, and identifying a root cause using a defect identification algorithm that traces back the cause of the defect in an opposite direction to that in which the defect is propagated based on an OTN layer structure.