Systems and methods are provided for generating a model for detection of seismic events. In this regard, one or more processors may receive from one or more stations located along an underwater optical route, one or more time series of polarization states of a detected light signal during a time period. The one or more processors may transform the one or more time series of polarization states into one or more spectrums in a frequency domain. Seismic activity data for the time period may be received by the one or more processors, where the seismic activity data include one or more seismic events detected in a region at least partially overlapping the underwater optical route. The one or more processors then generate a model for detecting seismic events based on the one or more spectrums and the seismic activity data.

A distributed optical fiber sensing (DOFS)/distributed acoustic sensing (DAS) method employing polarization diversity combining and spatial diversity combining for a DOFS/DAS system wherein the polarization diversity combining determines a temporal average product for each beating product, determines one having a max average power, rotates that one having max average power for its phase shift to produce a reference, determines a phase difference for each beating product as compared to the reference, compensates any phase difference such that all beating products exhibit a well-aligned phase; and combining the beating products; and wherein the spatial diversity combining uses the combined beating products for each location, determines a temporal average power, determines a location having a greatest average power; and combines the results and provides an indicia of the combined result(s).

Aspects of the present disclosure describe distributed optical fiber sensing systems, methods, and structures that advantageously employ point sensors that send sensory data/information over an attached, distributed optical fiber sensor without using a separate network or communications facility.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS)-distributed acoustic sensing (DAS) based systems, methods, and structures that advantageously enable and/or facilitate the monitoring of civil infrastructures via acoustic wave speed measurements.

Systems, methods, and structures that provide distributed acoustic sensing using chirped optical pulses of selectable duration and bandwidth, at a frame rate limited by a round-trip propagation time of a fiber under test. Instead of processing a transmitted chirped pulse as a single sequence—our systems, methods, and structures employ a parallel fragmented multiband architecture, where each tributary correlates the received signal with a truncated chirped pulse to obtain the Rayleigh impulse response over its frequency band. By reducing the duration of the chirp processed by each tributary, spatial leakage is reduced at all the tributaries, thus even after combining all the interferometric products from all tributaries using a rotated vector sum, the resultant signal is much less impacted by spatial leakage than by using a conventional TGD-OFDR method.

A photovoltaic unit that includes a biological interface for sensing an electrical signal from the biological tissue, the biological interface including a multilayered piezoelectric amplifier including a composite impulse generating layer including a matrix of a piezo polymeric material and dispersed phases including piezo nanocrystals and carbon nanotubes. The photovoltaic unit also includes a transducer structure comprising a fiber substrate having quantum dots present on a receiving end of the fiber. The receiving end of the fiber receiving the electrical signal. The quantum dots converts the electrical signal to a light signal.

Systems and methods are provided for utilizing polarization parameters obtained from an optical network to determine vibrations in optical fibers using coherent optics equipment and machine learning techniques. A method, according to one implementation, includes the step of obtaining a time-series dataset that includes measurements of polarization characteristics of light traversing an optical fiber of an optical network. The method also includes the step of detecting vibration characteristics of the optical fiber based on the time-series dataset. In some implementations, the time-series dataset may be a multi-variate dataset and the polarization characteristics may be related to transients in a State of Polarization (SOP). The SOP, for example, may be represented by an amplitude and a phase of an electric field vector and may be defined as having one of a linear polarization, elliptical polarization, and circular polarization.

A method of detecting sand inflow into a wellbore is disclosed. The method can include obtaining a sample data set, detecting a broadband signal within the sample data set, comparing the broadband signal with a signal reference, determining that the broadband signal meets or exceeds the signal reference, and determining the presence of sand inflow into the wellbore based on determining that the broadband signal meets or exceeds the signal reference. The sample data set can be a sample of an acoustic signal originating within a wellbore including a fluid, and the broadband signal at least includes a portion of the sample data set at frequencies above 0.5 kHz.

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.

Described herein is an optical fibre mounting structure (180) for fibre vibration sensing of a distributed system (100) of spaced apart vibration sources (112-131). Mounting structure (180) includes a base portion (200) having a two dimensional surface area defining a vibration surface (202). A mounting apparatus (236) is adapted to mount the base portion (200) to a support structure (e.g. 104) of the distributed system (100) adjacent one of the vibration sources. A fibre engagement structure (e.g. 210-215) is provided for supportively engaging a length (218) of optical fibre in contact with the vibration surface (202).