Abstract: A distributed acoustic sensing (DAS) system based on random fiber lasing amplification (RFLA) and a Rayleigh scattering enhanced fiber (RSEF), and relates to the field of distributed optical fiber sensing. The system comprises a DAS demodulation unit, a high-order RFLA unit and a RSEF. The present disclosure adopt the high-order RFLA technology to replace the traditional high-order distributed Raman amplification technology, and it does not need to use a plurality of pumps with different wavelength, and only needs a high-order random fiber laser pump and a broadband reflector to provide feedback for cascaded random fiber lasings to perform distributed amplification on signal light. By using high-order RFLA combined with the RSEF, high-efficiency and low-threshold RFLA can be achieved, and the signal-to-noise ratio and performances of a DAS system can be further improved, which enables realization of long-distance and high-performance distributed acoustic sensing.

Abstract: The present invention relates to an intelligent fiber optical distributed acoustic sensing (FODAS) system and method based on an artificial intelligence (AI) chip, belonging to the field of distributed optical fiber sensing technologies. The system comprises a light source, a modulator, an optical amplifier, a sensing part, a data processor, a photoelectric detector, and an alarm unit, where the data processor is specifically an AI chip; the light source, the modulator, the optical amplifier and port a of a circulator are connected in sequence, port b of the circulator is connected to an optical fiber, port c of the circulator is connected to the photoelectric detector, an output end of a detector is connected to the data processor, an output end of the data processor is connected to the alarm unit; and the data processor receives external acoustic signals and extracts amplitude and frequency features of the external acoustic signals to identify the type.

Abstract: The present invention provides an intelligent geophysical data acquisition system and acquisition method for shale oil and gas optical fiber. A pipe string is arranged in a metal casing, and an external armored optical cable is fixed outside the metal casing; an, internal armored optical cable is fixed outside the pipe string; the external armored optical cable comprises a downhole acoustic sensing optical cable, two multi-mode optical fibers, a strain optical cable and a pressure sensor array, and further comprises horizontal ground acoustic sensing optical cables arranged in the shallow part of the ground according to an orthogonal grid, and artificial seismic source excitation points arranged on the ground according to the orthogonal grid.

Abstract: A 1D-CNN-based ((one-dimensional convolutional neural network)-based) distributed optical fiber sensing signal feature learning and classification method is provided, which solves a problem that an existing distributed optical fiber sensing system has poor adaptive ability to a complex and changing environment and consumes time and effort due to adoption of manually extracted distinguishable event features.

Abstract: The present invention discloses a narrow-band, low-noise Raman fiber laser with a random fiber laser pump, pertaining to the technical field of fiber lasers and comprising an ytterbium-doped random fiber laser for producing ytterbium-doped random fiber lasing as the pump of a cascaded Raman random laser; the ytterbium-doped random fiber laser consists of a pump light source, a pump combiner, an ytterbium-doped fiber and a single-mode fiber connected in sequence, as well as a first narrow-band reflector connected to the signal end of the pump combiner. Ytterbium-doped random fiber lasing as the pump of the pump light source disclosed in the present invention is produced by an ytterbium-doped random fiber laser consisting of a narrow-band point reflector, an ytterbium-doped fiber, and a single-mode fiber and further serves as the pump of a Raman light source to achieve random laser output.

Abstract: A fully distributed magnetic adsorption multi-parameter sensing cable, which is configured to be installed on the wall of a metal pipeline, includes an outer sheath, a sensing component arranged in the outer sheath, and a fully distributed magnetic adsorption reinforcement (FDMAR) arranged in the outer sheath and on a peripheral side of the sensing component. The outer sheath is attached to the wall of the metal pipeline by the FDMAR. A magnetic adsorption force between the FDMAR and the wall of the metal pipeline is able to be adjusted by changing the size of the FDMAR and the distance between the FDMAR reinforcement and the wall of the metal pipeline. The fully distributed magnetic adsorption multi-parameter sensing cable has the advantages of good adsorption effect and high sensitivity.

Abstract: A distributed acoustic sensing (DAS) system based on space-division multiplexing with multi-core fiber (MCF) is proposed. It relates to a technical field of distributed optical fiber sensing. The present invention maintains the advantage of single-ended measurement in the standard DAS system, and realizes the intensity accumulation of the Rayleigh backscattering light within each core of the MCF, which can greatly improve the strain resolution of DAS systems. Moreover, the introduction of optical switch can make different code sequences transmit in the different core of the MCF simultaneously, which can make the single-pulse response with coding gain demodulated without sacrificing the frequency responding bandwidth. Furthermore, the utilization of space-division multiplexing can make multiple pulses with precious time delay transmit in the MCF simultaneously, which can greatly improve the frequency responding bandwidth of DAS system.

Abstract: A long-distance FODAS amplification system includes a distributed amplification unit, which includes a LEAF, a pump, and a WDM; wherein the pump light passes through the WDM into the LEAF, so as to realize distributed amplification. A long-distance FODAS amplification method includes steps of: 1) modulating and amplifying a light source to obtain the probe pulse light; 2) guiding the pump light and the probe pulse light into LEAF; 3) combining the probe pulse light with the pump light to perform distributed amplification, so as to generate power-raised Rayleigh backscattered light; and 4) converting and demodulating the Rayleigh backscattered light after being output through the circulator, so as to complete distributed sensing.

Abstract: The present invention relates to an intelligent fiber optical distributed acoustic sensing (FODAS) system and method based on an artificial intelligence (AI) chip, belonging to the field of distributed optical fiber sensing technologies. The system comprises a light source, a modulator, an optical amplifier, a sensing part, a data processor, a photoelectric detector, and an alarm unit, where the data processor is specifically an AI chip; the light source, the modulator, the optical amplifier and port a of a circulator are connected in sequence, port b of the circulator is connected to an optical fiber, port c of the circulator is connected to the photoelectric detector, an output end of a detector is connected to the data processor, an output end of the data processor is connected to the alarm unit; and the data processor receives external acoustic signals and extracts amplitude and frequency features of the external acoustic signals to identify the type.

Abstract: A fully distributed magnetic adsorption multi-parameter sensing cable, which is configured to be installed on the wall of a metal pipeline, includes an outer sheath, a sensing component arranged in the outer sheath, and a fully distributed magnetic adsorption reinforcement (FDMAR) arranged in the outer sheath and on a peripheral side of the sensing component. The outer sheath is attached to the wall of the metal pipeline by the FDMAR. A magnetic adsorption force between the FDMAR and the wall of the metal pipeline is able to be adjusted by changing the size of the FDMAR and the distance between the FDMAR reinforcement and the wall of the metal pipeline. The fully distributed magnetic adsorption multi-parameter sensing cable has the advantages of good adsorption effect and high sensitivity.

Abstract: A random distributed Rayleigh feedback fiber laser based on a double-cladding weakly ytterbium-doped fiber includes: a pump laser source, a pump combiner, a cladding power stripper, and a double-cladding weakly ytterbium-doped fiber for simultaneously achieving distributed active gain and random distributed Rayleigh feedback. An output end of the pump combiner is connected with one end of the double-cladding weakly ytterbium-doped fiber, the other end of the double-cladding weakly ytterbium-doped fiber is connected with an input end of the cladding power stripper, and a concentration of ytterbium ions in the double-cladding weakly ytterbium-doped fiber is in a range of 0.5×1023 to 1×1025/m3. The laser provided by the present invention solves the problem that the existing random fiber lasers cannot simultaneously utilize distributed active gain and random distributed Rayleigh feedback with a single type of fiber.

Abstract: A distributed optical fiber sensing signal processing method for safety monitoring of underground pipe network, which belongs to infrastructure safety monitoring field, which is aimed to improve the intelligent ability of detection and identification of the existing distributed optical fiber sound/vibration sensing system under complex application conditions. The present invention utilizes the distributed optical fiber sound/vibration sensing system to pick up the sound or vibration signal of the whole line along the detection cable; and the customized short time feature and long time feature are respectively extracted from the relative quantity of the sound or the vibration signal at each spatial point in the whole monitoring range. The Bayesian identification and classification network at each spatial point is constructed and trained based on the prior knowledge of the collected signal features and their different background noises.

Abstract: A speckle-free imaging light source based on a random fiber laser (RFL) using a strong-coupling multi-core optical fiber, relating to a field of optical fiber laser illumination light source, is provided, mainly including a pumping source and an optical fiber loop mirror, and further including the strong-coupling multi-core optical fiber with/without a single-mode optical fiber. Through directly adopting the strong-coupling multi-core optical fiber or combining the single-mode optical fiber with the strong-coupling multi-core optical fiber to serve as a main device in the RFL-based illumination light source, the generated RFL has multiple transvers modes and low spatial coherence which prevent speckle formation during illumination, which provides an ideal illumination light source for high-speed full-field speckle-free imaging technology.

Abstract: A method of improving measurement speed of distributed optical fiber sensors by adopting orthogonal signals and the system thereof is disclosed, which is related to the optical fiber sensor field and solves the problems that conventional technology will increasing the bandwidth of the received signal, reducing the signal-to-noise ratio of the received signal or distortion the spatial resolution of the system. The method comprises steps of generating N periodic orthogonal optical pulse sequence; injecting the N periodic orthogonal optical pulse sequence into the optical fiber under test(5); collecting the scattered light signal; demodulating the scattered light signal with the local oscillating light and then converting into digital signals; extracting the scatter information of the orthogonal optical pulses from the collected digital signals; and arranging the scattered information in order of precedence of the infusion. The measurement speed of the distributed optical fiber sensors is improved by N?1 times.

Abstract: A hybrid distributed amplification method based on a random fiber laser generated within erbium fiber with low doping concentration, i.e. weak erbium-doped fiber (WEDF), which includes: Step 1. constructing a fiber link via WEDF; Step 2. generating the random fiber laser based on the fiber link, the pump source, the wavelength division multiplexer and the strong feedback module; Step 3. constructing the spatial equalized gain based on hybrid gain of the erbium fiber and random fiber laser; Step 4. the signal is amplified by the hybrid spatial equalized gain. The present invention solves the typical problem of high laser threshold and low pump conversion efficiency when conventional fiber is used to generate random fiber laser for distributed amplification.

Abstract: A long-distance FODAS amplification system includes a distributed amplification unit, which includes a LEAF, a pump, and a WDM; wherein the pump light passes through the WDM into the LEAF, so as to realize distributed amplification. A long-distance FODAS amplification method includes steps of: 1) modulating and amplifying a light source to obtain the probe pulse light; 2) guiding the pump light and the probe pulse light into LEAF; 3) combining the probe pulse light with the pump light to perform distributed amplification, so as to generate power-raised Rayleigh backscattered light; and 4) converting and demodulating the Rayleigh backscattered light after being output through the circulator, so as to complete distributed sensing.

Abstract: A distributed acoustic sensing (DAS) system based on space-division multiplexing with multi-core fiber (MCF) is proposed. It relates to a technical field of distributed optical fiber sensing. The present invention maintains the advantage of single-ended measurement in the standard DAS system, and realizes the intensity accumulation of the Rayleigh backscattering light within each core of the MCF, which can greatly improve the strain resolution of DAS systems. Moreover, the introduction of optical switch can make different code sequences transmit in the different core of the MCF simultaneously, which can make the single-pulse response with coding gain demodulated without sacrificing the frequency responding bandwidth. Furthermore, the utilization of space-division multiplexing can make multiple pulses with precious time delay transmit in the MCF simultaneously, which can greatly improve the frequency responding bandwidth of DAS system.

Abstract: A hybrid distributed amplification method based on a random fiber laser generated within erbium fiber with low doping concentration, i.e. weak erbium-doped fiber (WEDF), which includes: Step 1. constructing a fiber link via WEDF; Step 2. generating the random fiber laser based on the fiber link, the pump source, the wavelength division multiplexer and the strong feedback module; Step 3. constructing the spatial equalized gain based on hybrid gain of the erbium fiber and random fiber laser; Step 4. the signal is amplified by the hybrid spatial equalized gain. The present invention solves the typical problem of high laser threshold and low pump conversion efficiency when conventional fiber is used to generate random fiber laser for distributed amplification.

Abstract: A random distributed Rayleigh feedback fiber laser based on a double-cladding weakly ytterbium-doped fiber includes: a pump laser source, a pump combiner, a cladding power stripper, and a double-cladding weakly ytterbium-doped fiber for simultaneously achieving distributed active gain and random distributed Rayleigh feedback. An output end of the pump combiner is connected with one end of the double-cladding weakly ytterbium-doped fiber, the other end of the double-cladding weakly ytterbium-doped fiber is connected with an input end of the cladding power stripper, and a concentration of ytterbium ions in the double-cladding weakly ytterbium-doped fiber is in a range of 0.5×1023 to 1×1027/m3. The laser provided by the present invention solves the problem that the existing random fiber lasers cannot simultaneously utilize distributed active gain and random distributed Rayleigh feedback with a single type of fiber.

Abstract: A 1D-CNN-based ((one-dimensional convolutional neural network)-based) distributed optical fiber sensing signal feature learning and classification method is provided, which solves a problem that an existing distributed optical fiber sensing system has poor adaptive ability to a complex and changing environment and consumes time and effort due to adoption of manually extracted distinguishable event features, The method includes steps of: segmenting time sequences of distributed optical fiber sensing acoustic and vibration signals acquired at all spatial points, and building a typical event signal dataset; constructing a 1D-CNN model, conducting iterative update training of the network through typical event signals in a training dataset to obtain optimal network parameters, and learning and extracting 1D-CNN distinguishable features of different types of events through an optimal network to obtain typical event signal feature sets; and after training different types of classifiers through the typical event sign