In the field of measuring physical parameters with a multimode optical fiber, a system for measuring P physical parameters at one or more measurement points has one or more multimode optical fibers. The system includes: a light source generating a source optical signal, a multimode measurement optical fiber transporting optical signals in at least M distinct second predetermined propagation modes, M being an integer greater than or equal to P, the measurement optical fiber including a measurement section reflecting the optical signals with a wavelength variable according to physical parameters to be measured, a detection device measuring wavelengths of the optical signals reflected by the measurement section, and an optical module generating M signals from the source optical signal, the M signals each being injected into the measurement optical fiber to propagate in one of the modes, the optical module also transferring the optical signals reflected toward the detection device.

The invention relates to a device and method for detecting an acoustic wave propagating toward a membrane, the membrane carrying a waveguide comprising an optical cavity defining a resonant frequency. Under the effect of a vibration of the membrane, the resonance frequency of the optical cavity varies. The device includes a light source for directing a light wave into the optical cavity, and a servo circuit for servo-controlling the wavelength of the light wave to the resonant wavelength of the optical cavity. Monitoring the variation in the wavelength of the light wave allows an amplitude of the acoustic wave to be estimated.

An energetic material device is disclosed. The energetic material device can include a casing. The energetic material device can also include an energetic material in a solid state within the casing. In addition, the energetic material device can include an optical sensor encased within the energetic material to sense a condition of the energetic material. An energetic material monitoring system is also disclosed. The energetic material monitoring system can include an energetic material device. The energetic material device can include a casing. The energetic material device can also include an energetic material in a solid state within the casing. In addition, the energetic material device can include an optical sensor encased within the energetic material. The energetic material monitoring system can also include an interrogator in communication with the optical sensor via an optical fiber.

A sensor system includes a sensor network comprising at least one optical fiber having one or more optical sensors. At least one of the optical sensors is arranged to sense vibration of an electrical device and to produce a time variation in light output in response to the vibration. A detector generates an electrical time domain signal in response to the time variation in light output. An analyzer acquires a snapshot frequency component signal which comprises one or more time varying signals of frequency components of the time domain signal over a data acquisition time period. The analyzer detects a condition of the electrical device based on the snapshot frequency component signal.

A load sensing system for sensing a load on a structure can include an optical load sensing element configured to change an optical state based on a force applied thereto, an optical source operatively connected to the optical load sensing element and configured to input an input optical signal to the optical load element, and an optical detector configured to receive a returned optical signal from the optical load sensing element. The optical detector can be configured to detect one or more frequency peaks of the returned optical signal and to use the one or more frequency peaks of the returned optical signal to correlate to a load value of the load and output the load value indicative of the load.

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.

Some embodiments of the disclosure provide a demodulation system for obtaining phase change parameters by a fiber-optic Fabry Perot sensor. In an embodiment, the demodulation system includes a transmitting module, a fiber-optic Fabry Perot sensor, a light splitting module, a filter module, a receiving module, and a processing module. The transmitting module transmits a beam with a predetermined wavelength range. The fiber-optic Fabry Perot sensor receives the beam and forms a reflected light beam. The light splitting module is arranged between the transmitting module and the fiber-optic Fabry Perot sensor. The filter module obtains the first light beam, the second light beam, and the third light beam. The filter module has a broadband filter. The receiving module receives the first light beam, the second light beam, and the third light beam and converts them into the first signal, the second signal, and the third signal.

A system, apparatus, and method for demodulation of a fiber optic sensor is provided. An aspect of the system provides an optical fiber, a laser, a phase modulator configured to be coupled to the optical fiber, and a sensor. The laser emits a laser beam into the optical fiber. The phase modulator receives the laser beam from the laser and directs the laser beam to the sensor. The sensor includes a coiled portion of the optical fiber, uncoiled segments adjacent the coiled portion, and at least two fiber Bragg gratings configured to be coupled to opposite uncoiled segments adjacent the coiled portion of the optical fiber. The sensor system may further include a photodetector configured to receive a reflected portion of the laser beam from the sensor. The reflected portion is divided into at least two paths where at least two sub-outputs are generated for demodulation and sensing.

A miniature, micrometer-accuracy, three-dimensional (3D) position-to-optical displacement sensor that has at least one extrinsic Fabry-Perot interferometer (EFPI) in Z direction and a series of plasmonic metasurface resonators with distinctive wavelength-selective characteristics in X and Y directions. The interferometer comprises at least one single mode optic fiber for light propagation, and a substrate mirror to create a light interference fringe as a function of distance between the mirror and the distal end of the optic fiber. Each plasmonic resonator is capable of modifying the substrate mirror and comprises an array of multiple unit nanostructure unit cells that are arranged in a two-dimensional (2D) square lattice or array in the X-Y plane. The nanostructure unit cells are preferably inscribed in the top layer of a three-layer thin film via the focused ion beam (FIB).

An optical fiber sensor includes optical sensor elements, for instance a plurality of multiplexed Bragg gratings, a broadband optical source, an interferometer with at least one polarization-maintaining fiber section with which a birefringence modulator, a signal generator and a receiver are associated. The optical birefringence in the propagation medium, i.e., in the polarization-maintaining fibre, combined with the birefringence of the birefringence modulator, produce in the interferometer the path difference and thereby the interference fringes which, appropriately processed according to the known technique, allow the measurement to be traced. The use of a birefringence modulator associated with the polarization-maintaining fiber allows a high-speed modulation of the interferometer, thus allowing high sampling rates of the sensor without having variations in responsivity depending on the alignment of the sensors with the interferential fringes of the interferometer.