An optical fiber sensing range limiting device comprises: a blocking unit that, on the basis of a control signal and for a prescribed period, causes probe light that has been sent to an optical fiber used in optical fiber sensing and has returned from the optical fiber to be blocked from being transmitted to a light detection unit, or causes a detection signal that is detected with respect to the return light to be blocked from being transmitted to a downstream processing unit; and a control unit that outputs the control signal to the blocking unit. The prescribed period includes a period corresponding to the positional range for which acquisition of information from the detection signal is prohibited or for which it is undesirable to acquire the information.

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.

A computer-readable, non-transitory medium storing a program that causes a computer to execute a process is provided. The process includes acquiring a backward Rayleigh scattered light from an optical fiber composite overhead ground wire provided along an electrical power transmission line, determining each of spectral densities of each of frequencies of vibration of the optical fiber composite overhead ground wire, on a basis of the backward Rayleigh scattered light, estimating a wind speed of a wind hitting the electrical power transmission line, on a basis of a first spectral density of a first frequency band including a natural frequency of the optical fiber composite overhead ground wire, and estimating a wind direction of the wind, on a basis of a second spectral density of a second frequency band which does not include the natural frequency of the optical fiber composite overhead ground wire.

A semi-translucent photovoltaic device is described having a translucent substrate with a photovoltaic stack interrupted in spatially distributed openings filled with a translucent polymer. Also disclosed is a method of manufacturing the device. The method comprises providing the substrate at a first side with the photovoltaic stack; removing material from the stack in spatially distributed regions, therewith forming openings within these regions; blanket-wise depositing a protective layer over the substrate with the photovoltaic stack; blanket-wise depositing a layer of a radiation-curable precursor for the translucent polymer over the protective layer; irradiating the substrate from a second side opposite its first side to therewith selectively cure the radiation-curable precursor within and in front of the spatially distributed openings, the radiation-curable precursor being converted therewith into said translucent polymer; removing an uncured remainder of the layer of the radiation-curable precursor.

A well system includes a fiber-optic cable that can be positioned downhole along a wellbore. The well system further includes a plurality of opto-electrical interfaces to communicatively couple to the fiber-optic cable to monitor temperature and strain along the fiber-optic cable. Additionally, the well system includes a processing device and a memory device that includes instructions executable by the processing device to cause the processing device to perform operations. The operations include receiving data representing frequency or phase shift measurements from the opto-electrical interfaces using at least two frequency or phase shift measurement techniques. Further, the operations include generating a temperature shift output and a strain change output using an inversion comprising sensitivity ratios and the data representing the frequency or phase shift measurements from the plurality of opto-electrical interfaces.

An optical system performs a method for measuring an acoustic signal in a wellbore. The optical system includes a light source, an optical fiber and a detector. The light source generates a light pulse. The optical fiber has a first end for receiving the light pulse from the light source and a plurality of enhancement scatterers spaced along a length of the optical fiber for reflecting the light pulse. A longitudinal density of the enhancement scatterers increases with a distance from the first end to increase a signal enhancement generated by the enhancement scatterers distal from the first end. The detector is at the first end of the optical fiber and measures a reflection of the light pulse at the enhancement scatterers to determine the acoustic signal.

The present invention is to provide a backscattered light amplification device, an optical pulse test apparatus, a backscattered light amplification method, and an optical pulse test method for amplifying a desired propagation mode of Rayleigh backscattered light with a desired gain by stimulated Raman scattering in a fiber under test having the plurality of propagation modes. The backscattered light amplification device according to the present invention is configured to control individually power, incident timing, and pulse width of a pump pulse for each propagation mode when the pump pulse is incident in a plurality of propagation modes after the probe pulse is input to the fiber under test in any propagation mode.

Distributed fiber optic sensing (DFOS) systems and methods that automatically detect vibration signal patterns from waterfall data recorded by DFOS system operations in real- time and associate the detected vibration signal patterns to GPS location coordinates without human intervention or interpretation. When embodied as a computer vision-based operation according to aspects of the present disclosure, our inventive systems and method provide accurate, cost-efficient, and objective determination without relying on humans and their resulting bias' and inconsistencies.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS) systems, methods, and structures that advantageously sense/monitor outdoor facilities and structures including outdoor cabinets containing fiber optic facilities in which the cabinet/fiber optic cable contained therein are configured to provide superior acoustic sensing. Further outdoor facilities and structures that are monitored include manhole structures. Superior DFOS/DAS monitoring results are obtained by employing a machine learning-based analysis method that employs a temporal relation network (TRN).

This application describes a fibre optic cable structure which is advantageous for distributed fibre optic sensing, for example distributed acoustic sensing (DAS). The fibre optic cable structure includes an optical fibre for distributed fibre optic sensing and is configured to comprise at least one longitudinal section of a first type, which exhibits a change in effective optical path length of the optical fibre of one polarity in response to a given applied force, and which is adjacent to at least one longitudinal section of a second type, which exhibits a change in effective optical path length of the optical fibre of the opposite polarity in response to an equivalent applied force. When used for DAS, the response of a sensing portion that includes sections of both the first and second types, will include or exclude certain wavenumber by summation, which provides a directional sensitivity to incident waves.