A sensor. In some embodiments, the sensor includes a first waveguide, a flexible support element, and a second waveguide. A first portion of the first waveguide may be supported by the flexible support element and separated by a first gap from a second portion of the first waveguide. The flexible support element may be capable of bending so as to cause an effective index of refraction of the first waveguide to change. The first waveguide may be coupled to the second waveguide through a second gap, the second gap being at an end of the first waveguide and an end of the second waveguide.

An optical fiber sensing system according to the present disclosure includes an optical fiber (10) that detects vibration, a detection unit (21) that detects occurrence of a predetermined event, based on an optical signal on which vibration detected by the optical fiber (10) is superimposed, an identification unit (22) that identifies an occurrence location of the predetermined event, based on the optical signal, and identifies a movement destination area serving as a moving destination of an unmanned aerial vehicle that monitors an occurrence location of the predetermined event, based on an occurrence location of the predetermined event, and a control unit (23) that controls the unmanned aerial vehicle to move to the movement destination area.

Disclosed are distributed fiber optic sensing arrangements that—in sharp contrast to the prior art—utilize C-OTDR capabilities to detect an optical fiber end point while still maintaining operational DFOS vibration/acoustic signal sensing functions. Advantageously, such operations are performed automatically without requiring a manual confirmation. A change is made in digital signal processing in the C-OTDR operation by bypassing a high-pass-filtering stage when calculating intensity changes such that the DC signal component is preserved and used to differentiate from a “no-fiber” section. It then calculates the no-fiber section's signal level and uses a back-tracking operation to determine the fiber end automatically.

An optical fiber sensor system includes a light source, a modulation unit, an optical coupler, a polarization separator, a first polarization controller optically coupled to the polarization separator, and a first detection unit that includes a first optical detector that receives the first component, converts the first component into a first electrical signal, and detects stress. The first polarization controller controls a polarization state of light input to the polarization separator so that the first electrical signal exhibits a first-order response to the stress.

A distributed fiber optic acoustic detection device employs a novel distributed acoustic detection method using a phase noise cancelling distributed acoustic sensing (PNC-DAS) technique.

A method for determining characteristics of a test cavity, the method includes for each of a plurality of optical frequencies within a bandwidth of a tunable laser, measuring interference signals from the test cavity and a reference cavity having a known characteristic. The method includes determining values for the plurality of optical frequencies from the measured interference signals from the reference cavity and the known characteristic of the reference cavity, and determining the characteristic of the test cavity using the determined values of the plurality of optical frequencies.

The present invention relates to an opto-mechanical transducer comprising an optical fibre exhibiting a polished pointed distal end placed opposite a reflecting surface and a proximal end being linked up to a coupler combining an illumination optical fibre associated with a light source and a measurement optical fibre associated with a photo-detector. The reflecting element exhibits a movable zone with an axial component, the axial distance between the distal end of the optical fibre and said reflecting surface at rest is determined so that the reflected luminous intensity I.sub.0 is equal to P.Math.I.sub.max where I.sub.max denotes the maximum reflected luminous intensity, and P is a parameter lying between 0.25 and 0.75.

A method of distributed acoustic sensing includes providing a fiber optic distributed acoustic sensing system having a cable. A straight optical fiber extends parallel to a longitudinal axis of the cable along the cable length. A helically wrapped optical fiber extends along the cable length. The method includes transmitting optical signals into and receiving backscattered signals out of the optical fibers consisting of a component of said optical signals which component has been backscattered from impurities or inhomogeneities in the optical fibers, observing changes in the backscattered signals caused by axial stretching and compressing of the optical fibers caused by an incident wave, comparing the backscattered signals of the straight optical fiber and the helically wrapped fiber, and determining, based on the comparing of the backscattered signals, a direction of wave propagation of the incident wave with respect to the fiber axis for detecting broadside waves and axial waves distinguishably.

A fiber optic MEMS microphone featuring an electrically deflectable MEMS membrane via a conversion of an optical energy propagating in an optical fiber cable to an electrical energy with a photodiode chip. The fiber optic MEMS microphone includes a MEMS device, the photodiode chip, a voltage, a power adjustable laser beam and a light.

The invention relates to a system and method for detecting vibrations on the periphery of an optical fibre, which is divided into five subsystems that are connected together. First, a light-source subsystem (6) generates light, which is transmitted through an optical fibre subsystem (2). Then, speckle interference patterns generated in the optical fibre are read using a CMOS micro camera subsystem (5). Subsequently, the information is analysed by a processing subsystem (7), producing an alarm signal that is notified to the outside by means of a communications subsystem (1).