An optical fiber sensing system according to this disclosure includes: a first optical fiber network (10A) configured to detect first sensing information about a monitoring target; a second optical fiber network (10B) configured to detect second sensing information about the monitoring target; a first reception unit (21A) configured to receive a first light signal from the first optical fiber network (10A); a second reception unit (21B) configured to receive a second light signal from the second optical fiber network (10B); and an identification unit (22) configured to identify the monitoring target, based on the first sensing information included in the first light signal, and the second sensing information included in the second light signal.

To apply an optical amplification repeater device to optical fiber sensing to lengthen a sensing range, as well as to enable compatibility with an optical communication system a cable system that uses a cable for optical fiber communication and optical fiber sensing of an environment surrounding the cable, wherein: the optical fiber communication is bidirectional communication using optical fiber pairs which are pairs of the optical fiber; in an optical fiber, a first wavelength band and a second wavelength band are different from each other; an optical amplification unit included in the optical amplification repeater device includes a first amplifier and a second amplifier that amplify rays of light in mutually opposing directions; and each of the communication optical signal, the probe light, and the backscattering light is amplified by at least either the first amplifier or the second amplifier.

According to the present example embodiment, the optical fiber sensing system is an optical fiber sensing system being acquired by adding a function of optical fiber sensing to a cable of an optical communication cable system. The optical communication cable system includes the cable including an optical fiber core wire that propagates an optical signal for communication, and a plurality of devices. A function of the optical fiber sensing is a function of, by an interrogator, sending probe light to an optical fiber core wire, detecting backscattered light of the probe light, and performing sensing on environmental information around the cable. The device includes an optical wiring line through which sensing light passes without passing through an optical amplifier.

A method of detecting removal of a maintenance hatch includes transmitting an optical pulse along an optical fiber, wherein a first portion of the optical fiber is proximate to the maintenance hatch. The method further includes detecting backscatter light from the optical fiber using a sensor. The method further includes determining information related to the first portion of the optical fiber based on a comparison of the detected backscatter light and a trained model. The method further includes identifying whether the maintenance hatch has been removed based on the determined information.

A testing procedure including a data collection procedure and a contrastive learning-based approach, for establishing a profile for utility poles surveyed in an embedding space. Unique properties of utility poles are preserved in a low-dimensional feature vector. Similarities between pairs of samples collected at the same or different poles is reflected by the Euclidean distance between the pole embeddings. During data collection—variabilities of excitation signals are manually introduced, e.g. impact strength, impact locations, impact time ambiguity, data collecting location ambiguity on a DFOS/DAS optical sensor fiber/cable. Data so collected provides a learned model learned complete information about a utility pole and is more robust with respect to uncontrollable factors during operation. A model training procedure that effectively extracts a utility pole intrinsic properties (e.g., structure integrity, dimensions, structure variety) and remote extrinsic influence (e.g., excitation strength, weather conditions, road traffic), without knowing the ground truth of these factors. The only identifying label required is an ID of any tested poles, which is readily available. The model is trained adaptively—end-to-end—is advantageously easy-to-implement on modern deep learning frameworks such as PyTorch.

An optical sensing system for detecting fiber events along an optical cable under test (CUT) having forward and feedback fibers and multiple pairs of optical couplers interconnected along the forward and feedback fibers in a ladder topology. An optical transmitter generates an optical probing signal for a forward fiber, wherein the couplers along the forward fiber provide tapped portions of the probing signal to the couplers along a feedback fiber to form a combined optical feedback signal in the feedback fiber. A reference coupler is connected between the transmitter and the forward fiber to tap an optical reference signal from the probing signal, and a feedback coupler is connected to combine the reference signal and the feedback signal. An optical receiver receives and processes the combined reference and feedback signals from the feedback coupler to detect fiber events along the CUT.

A method for measuring a response from an optical fiber providing distributed back reflections using a system comprising an optical source comprising a laser, an optical receiver and a processing unit is disclosed. The method comprises establishing initial parameters of a distributed back-reflection processing. The method also comprises generating an interrogation signal and an optical local oscillator using the optical source, the interrogation signal being represented by an interrogation phasor and the optical local oscillator being represented by a local oscillator phasor; transmitting the interrogation signal into the optical fiber; and mixing the optical local oscillator with reflected light from the optical fiber and detecting a mixing product with the optical receiver to achieve a receiver output signal. The method further comprises performing a measurement that characterizes the interrogation phasor; updating the parameters of the distributed back-reflection processing based on the measurement result such that an effect of fluctuations in the interrogation phasor on the measured response from the fiber is reduced; and applying distributed back-reflection processing to the receiver output signal. Finally, the method comprises extracting the response from the optical fiber from the distributed back-reflection processing output. A system for measuring a response from an optical fiber providing distributed back reflections is also disclosed.

This application described methods and apparatus for distributed fibre optic sensing. A sensing apparatus has a modulator which modulates radiation from an optical source to interrogate a sensing optical fibre with a first interrogation pulse at a first frequency (F1) and a second interrogation pulse at a second, different, frequency (F2), both different in frequency from a local oscillator (LO). A mixer mixes backscatter from the sensing optical fibre with the local oscillator and supplies the mixed signal to a detector that provides a corresponding digital signal. A processor processes the digital signal (DX, DY) in a first and second processing channels to demodulate respective first and second phase signals based on the respective frequency difference between the first and second frequency and the local oscillator and determines a temporal difference between the first and second phase signals.

An optical time-domain reflectometer (OTDR), where a laser emitting apparatus of the OTDR outputs a first optical signal in a first time period. A signal modulation apparatus of the OTDR generates a pulse signal based on the first optical signal, and outputs the pulse signal to an optical fiber in a second time period, where the first time period includes the second time period. A receiver of the OTDR receives a scattered signal from the optical fiber, where a frequency of the scattered signal is the same as a frequency of the first optical signal. Then, the laser emitting apparatus outputs a second optical signal in a third time period, where a frequency of the second optical signal is different from the frequency of the first optical signal. The second optical signal is used as a local oscillator signal to implement coherent detection in the receiver.

Distributed fiber optic sensing (DFOS) and artificial intelligence (AI) systems and methods for performing utility pole hazardous event localization that advantageously identify a utility pole that has undergone a hazardous event such as being struck by an automobile or other detectable impact. Systems and methods according to aspects of the present disclosure employ machine learning methodologies to uniquely identify an affected utility pole from a plurality of poles. Our systems and methods collect data using DFOS techniques in telecommunication fiber optic cable and use an AI engine to analyze the data collected for the event identification. The AI engine recognizes different vibration patterns when an event happens and advantageously localizes the event to a specific pole and location on the pole with high accuracy. The AI engine enables analyses of events in real-time with greater than 90% accuracy.