Systems and methods for measuring temperature in an environment by creating a first beam having an energy of about 50 mJ/pulse, and a pulse duration of about 100 ps. A second beam is also created, having an energy of about 2.3 mJ/pulse, and a pulse duration of about 58 ps. The first beam and the second beam are directed into a probe region, thereby expressing an optical output. Properties of the optical output are measured at a sampling rate of at least about 100 kHz, and temperature measurements are derived from the measured properties of the optical output. Such systems and methods can be used to measure temperature in environments exhibiting highly turbulent and transient flow dynamics.

An identification system (1) includes a transmitter (131) for transmitting pulsed light via an optical fiber (10); a receiver (132) for receiving backscattering light of the pulsed light from the optical fiber (10); a detector (133) for detecting, from the backscattering light, the condition of environment surrounding the optical fiber (10); and an identifier (320) for identifying sagging of the optical fiber (10) from a detection result by the detector (133).

Disclosed herein is a method for measuring temperature via distributed temperature sensing comprising transmitting light through a fiber optic cable; detecting backscattered light in the fiber optic cable, wherein the backscattered light comprises an anti-Stokes band and a Stokes band; calculating a ratio between an intensity of the anti-Stokes band and an intensity of the Stokes band; and using the calculated ratio to determine a temperature being sensed in the fiber optic cable; wherein the fiber optic cable comprises, from the center to the periphery; a central core having a refractive index that decreases progressively from a center of the central core to an edge of the core, wherein the refractive index follows an alpha profile; wherein a bandwidth-length product of the multimode optical fiber has a value greater than 2000 MHz-km at 1550 nm.

Disclosed herein is a method for measuring temperature via distributed temperature sensing comprising transmitting light through a fiber optic cable; detecting backscattered light in the fiber optic cable, wherein the backscattered light comprises an anti-Stokes band and a Stokes band; calculating a ratio between an intensity of the anti-Stokes band and an intensity of the Stokes band; and using the calculated ratio to determine a temperature being sensed in the fiber optic cable; wherein the fiber optic cable comprises, from the center to the periphery; a central core having a refractive index that decreases progressively from a center of the central core to an edge of the core, wherein the refractive index follows an alpha profile; wherein a bandwidth-length product of the multimode optical fiber has a value greater than 2000 MHz-km at 1550 nm.

A distributed temperature sensor system has a pulsed laser coupled to a circulator, the circulator having a laser input and coupling energy to an optical reference coil in series with a measurement fiber having loops or helical turns, the circulator having a backscatter signal port coupling backscattered reflections from the measurement fiber. The backscatter signal port is coupled to a switch and mux, the switch and mux selecting either an anti-Stokes filter or a Stokes filter, the output of the mux coupled to a photodetector, the photodetector coupled to a histogram processor synchronized to the pulsed laser enable. The histogram processor uses the anti-Stokes and Stokes histogram counts associated with a sensor region to estimate a temperature of that sensor region.

Disclosed are a distributed temperature sensing system using a multicore optical fiber and a method thereof. The distributed temperature sensing system using the multicore optical fiber is configured to use the multicore optical fiber for a typical distributed temperature sensing system (DTSS), analyze a signal by collecting, for all cores, Raman-scattered light that is backscattered by multiple cores, increase the size of the signal by the number of times corresponding to the number of cores, increase a signal-to-noise ratio (SNR) for the same sensing time, and increase a sensing distance.

Disclosed are a distributed temperature sensing system using a multicore optical fiber and a method thereof. The distributed temperature sensing system using the multicore optical fiber is configured to use the multicore optical fiber for a typical distributed temperature sensing system (DTSS), analyze a signal by collecting, for all cores, Raman-scattered light that is backscattered by multiple cores, increase the size of the signal by the number of times corresponding to the number of cores, increase a signal-to-noise ratio (SNR) for the same sensing time, and increase a sensing distance.

A temperature monitoring apparatus configured to monitor a temperature of a portion of a vehicle's electrical energy distribution network is disclosed. The apparatus includes a first optical fibre including one or more temperature sensing sections, each temperature sensing section being for thermal contact with a portion of a vehicle's electrical energy distribution network. Each temperature sensing section is arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section. The apparatus is arranged to determine a temperature of the portion of the vehicle's electrical energy distribution network based on one or more of the output optical signals in use.

According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device, or a radiation level associated with a device environment.

A procedure to solve the DFOS placement problem that uses a genetic algorithm to achieve a global optimization of sensor placement. First, our procedure according to aspects of the present disclosure defines a fitness function that counts the number of DFOS sensors used. Second, the procedure uses a valid DFOS placement assignment to model an individual in the genetic algorithm. Each individual consists of N genes, where N is the number of nodes in the given network infrastructure, e.g., N=|V|. Each gene has two genomes: (1) a list of 0s and/or 1s, in which is represent the network nodes that are equipped with DFOS sensors, and 0s represent the nodes that are not equipped with DFOS sensors; (2) a list of sensing fiber routes. An individual that has smallest number of is in their genes will be considered as the strongest individual. Thirdly, the procedure randomly generates a population of individuals. After a certain number of generations of population, the strongest individual in the last generation will be the global optima for the DFOS placement assignment.