There is described a sensor apparatus. It comprises an interrogator comprising a light source emitting pulses having a wavelength about an average wavelength; and a fiber Bragg grating (FBG) arrangement. The arrangement comprises a FBG sensor array comprising a plurality of FBG sensors on an optical fiber and being for reflecting the pulses, thereby producing reflected pulses at each one of the FBG sensors. FBG sensors of a given FBG sensor array have a spatial separation therebetween which is sufficient to allow, at a receiver, a temporal discrimination between the reflected pulses produced by each one of the FBG sensors. The FBG sensor array has a spectral reflection window which comprises the average wavelength.

A slight movement of the ground is detected. A cable, which includes an optical fiber, is provided to have friction with the ground in such a way that the optical fiber is expanded and contracted in accordance with the movement of the ground. An optical output unit outputs a monitoring light to the optical fiber. A partial reflection unit is provided on a path of the optical fiber in the cable and partially reflects the monitoring light. An optical reception unit receives a reflection light reflected by the partial reflection unit. A calculation unit measures the length of the optical fiber to the partial reflection unit based on a round-trip propagation time of the reflection light that has been received and monitors its changes over time.

Apparatus and associated methods relate to determining the wavelength of a narrow-band light beam. The narrow-band light beam is passed through an optical filter. The optical filter has complementary and monotonically-varying transmission and reflection coefficients within a predetermined band of wavelengths. The predetermined band of wavelengths includes the wavelength of the narrow-band light beam. A first photodetector detects amplitude of a first portion of the narrow-band light beam transmitted by the optical filter. A second photodetector detects amplitude of a second portion of the narrow-band light beam reflected by the optical filter. The wavelength of the narrow-band light beam is determined, based on a ratio of the determined amplitudes of the first and second portions of the narrow-band light beam transmitted and reflected, respectively.

Provided is an optical fiber sensor that is capable of highly accurately detecting an abnormality in a structure from vibration information. This optical fiber sensor includes an optical fiber that is laid in the vicinity of a structure, a light source for introducing pulsed light of a specific period into the optical fiber, and an optical sensor for detecting return light that has been obtained as a result of the introduction of the pulsed light into the optical fiber. The structure is determined to have an abnormality if the spectral centroid of vibration information exceeds a threshold.

Example embodiments include an optical interrogation system with a sensing fiber having a single core, the single core having multiple light propagating modes. Interferometric apparatus probes the single core multimode sensing fiber over a range of predetermined wavelengths and detects measurement interferometric data associated with the multiple light propagating modes of the single core for each predetermined wavelength in the range. Data processing circuitry processes the measurement interferometric data associated with the multiple light propagating modes of the single core to determine one or more shape-sensing parameters of the sensing fiber from which the shape of the fiber in three dimensions can be determined.

Methods and apparatuses to obtain increased performance and differentiation for an inductive position sensor through improvements to the sense element and target design are disclosed. In a particular embodiment, a sense element includes a transmit coil, a first receive coil that includes a first plurality of arrayed loops, wherein two or more of the first plurality of arrayed loops are at least one of phase blended and amplitude arrayed, and a second receive coil that includes a second plurality of arrayed loops, wherein two or more of the second plurality of arrayed loops are at least one of phase blended and amplitude arrayed, and wherein the first receive coil and the second receive coil are phase shifted. The sense element coils are arrayed in several geometries and layouts, and the coil and target geometry are manipulated to compensate for inherent errors in the fundamental design of an inductive position sensor.

A multilinear domain-specific domain generalization (MDSDG) approach that utilizes information stored in multilinear indices of data domains to improve machine learning. In particular—based on limited sample size(s) in observed scenarios—an array of models is jointly trained, which advantageously are generalized to a new, unseen scenario, where only domain descriptions in the form of multilinear indices are available.

A reflection mode sensor system may include an optical fiber core and an optical fiber cladding. A first long period grating (LPG) may be positioned along the optical fiber core having a first grating period, a second LPG may be positioned along the optical fiber core having a second grating period, and a third LPG may be positioned along the optical fiber core having a third grating period. The grating periods may enable sensing of multiple parameters simultaneously. A metal coating may be applied to an end facet of the combined optical fiber core and optical fiber cladding. The metal coating may also cover a side surface of the optical fiber cladding along a length from the end facet. The metal coating may include a paste applied to the optical fiber core and the optical fiber cladding, where the paste has been cured, and includes a metal.

In some examples, a microstructured fiber comprises a cladding material surrounding at least one core material, wherein the at least one core material comprises an array of discrete devices contacted in parallel. A method of producing a microstructured fiber may include 3D-printing a fiber preform, thermally drawing the fiber preform into a fiber that preserves the cross-sectional geometry of the fiber preform, and axially patterning the fiber into a microstructured fiber comprising an array of discrete devices contacted in parallel. In some embodiments, microstructured fibers may be integrated into a sensory textile that includes at least one of an electrooptic portion, a sonar portion, a magnetic gradiometer portion, and a piezogenerating portion. In some embodiments, microstructured fibers may be formed into an in-fiber integrated quantum device circuit or an in-fiber ion trap.

An advance in the art is made according to aspects of the present disclosure directed to distributed fiber optic sensing systems (DFOS), methods, and structures that advantageously provide the continuous monitoring of aerial cables using distributed acoustic sensing (DAS) and operational modal analysis (OMA).