Abstract: An interferometric demodulation system for a large capacity fiber grating sensing network is provided by the present disclosure, comprising: a continuous light output end of the nanoscale wide-spectrum light source is connected to an input end of the pulse optical modulator, an output end of the reference grating is connected to an input end of the grating array sensing network, and a third communication end of the optical circulator is connected to an input end of the optical amplifier, an output end of the optical amplifier is connected to an input end of the Mach-Zehnder interferometer, three-channel signal output ends of the Mach-Zehnder interferometer are respectively connected to signal input ends corresponding to the embedded signal processor through the photoelectric converter, and the embedded signal processor controls the heating device to control a temperature of an any one of interference arms of the Mach-Zehnder interferometer.

Abstract: An interferometric demodulation system for a large capacity fiber grating sensing network is provided by the present disclosure, comprising: a continuous light output end of the nanoscale wide-spectrum light source is connected to an input end of the pulse optical modulator, an output end of the reference grating is connected to an input end of the grating array sensing network, and a third communication end of the optical circulator is connected to an input end of the optical amplifier, an output end of the optical amplifier is connected to an input end of the Mach-Zehnder interferometer, three-channel signal output ends of the Mach-Zehnder interferometer are respectively connected to signal input ends corresponding to the embedded signal processor through the photoelectric converter, and the embedded signal processor controls the heating device to control a temperature of an any one of interference arms of the Mach-Zehnder interferometer.

Abstract: The present invention discloses a grating enhanced distributed vibration demodulation system based on three-pulse shearing interference, comprising: a laser device, a pulse optical modulator, a three-pulse generation polarization-maintaining structure, a first erbium-doped fiber amplifier, a first optical circulator, a fiber grating array, a second erbium-doped fiber amplifier, a second optical circulator, a three-in-three optical coupler, a first Faraday rotator mirror, a second Faraday rotator mirror, and a four-channel data acquisition card, On the basis of a distributed fiber grating vibration sensing system, three-pulse dislocation interference and three-in-three optical coupler digital phase demodulation technologies are adopted, XX and XY pulses are utilized to complement interference visibility, and demodulation is performed by selecting a better path, so that polarization fading resistance and interference signal high visibility in the distributed fiber grating vibration sensing system are realized.

Abstract: The present invention discloses a distributed pulsed light amplifier based on optical fiber parametric amplification, comprising a pump pulsed light source, a sensing pulsed light source, a synchronization device, a two-in-one optical coupler, an optical circulator, a parametric amplification optical fiber, a first optical filter, a photoelectric detector and a signal acquisition device. According to the distributed pulsed light amplifier, high-power pulsed light is used as pump light to generate an optical fiber parametric amplification effect near a zero-dispersion wavelength of an optical fiber, thereby amplifying a power of another sensing pulsed light. Meanwhile, due to the fact that effective optical fiber parametric amplification cannot be achieved through low-power light leakage outside a duration interval of the pump pulsed light, leaked light from the sensing pulsed light cannot be amplified, and the effect of amplifying a pulse extinction ratio can be achieved at the same time.

Abstract: The present invention discloses a distributed pulsed light amplifier based on optical fiber parameter amplification, comprising a pump pulsed light source, a sensing pulsed light source, a synchronization device, a two-in-one optical coupler, an optical circulator, a parameter amplification optical fiber, a first optical filter, a photoelectric detector and a signal acquisition device. According to the distributed pulsed light amplifier, high-power pulsed light is used as pump light to generate an optical fiber parameter amplification effect near a zero-dispersion wavelength of an optical fiber, thereby amplifying a power of another sensing pulsed light. Meanwhile, due to the fact that effective optical fiber parameter amplification cannot be achieved through low-power light leakage outside a duration interval of the pump pulsed light, leaked light from the sensing pulsed light cannot be amplified, and the effect of amplifying a pulse extinction ratio can be achieved at the same time.

Abstract: An optical fiber grating sensing method applied to small-scale fire source monitoring are provided, distinguishing two concepts of a spatial resolution and a perception resolution, under the premise of ensuring the spatial resolution of a traditional fiber Bragg grating sensing system, only increase the number of fiber Bragg gratings covered by a single pulsed optical signal without changing a pulse width of a pulsed optical signal, so as to improve the perception resolution of the system without increasing the requirements for a hardware circuit, and truly shorten an interval between adjacent fiber Bragg gratings. Improving the perception resolution of the system, which not only ensures the spatial resolution of the system, but also realizes the monitoring of small-scale fire sources; by adopting a simple feature extraction algorithm to obtain fire temperature information in different areas, the temperature detection speed of the system is fast.

Abstract: An optical fiber grating sensing method applied to small-scale fire source monitoring are provided, distinguishing two concepts of a spatial resolution and a perception resolution, under the premise of ensuring the spatial resolution of a traditional fiber Bragg grating sensing system, only increase the number of fiber Bragg gratings covered by a single pulsed optical signal without changing a pulse width of a pulsed optical signal, so as to improve the perception resolution of the system without increasing the requirements for a hardware circuit, and truly shorten an interval between adjacent fiber Bragg gratings. Improving the perception resolution of the system, which not only ensures the spatial resolution of the system, but also realizes the monitoring of small-scale fire sources; by adopting a simple feature extraction algorithm to obtain fire temperature information in different areas, the temperature detection speed of the system is fast.

Abstract: A method for correcting a phase jump caused by polarization-induced fading in optical fiber phase demodulation, including the steps of: 1, selecting a demodulated phase in the case of non-depolarization as historical sample data; 2, determining an autoregressive coefficient and a moving average coefficient of the autoregressive moving average model for the demodulated phase; 3, establishing a Kalman prediction model for the demodulated phase, and deriving recursive equations of the Kalman prediction model for the demodulated phase; and 4, judging whether a jump point exists in the actual demodulated phase, determining polarization states of lights if the jump point exists, and correcting the jump point when the polarization states of the lights are in polarization orthogonality by replacing the actual demodulated phase with a predicted phase value. The disclosure ensures the correctness of subsequent vibration-based signal processing.

Abstract: A method for correcting a phase jump caused by polarization-induced fading in optical fiber phase demodulation, including the steps of: 1, selecting a demodulated phase in the case of non-depolarization as historical sample data; 2, determining an autoregressive coefficient and a moving average coefficient of the autoregressive moving average model for the demodulated phase; 3, establishing a Kalman prediction model for the demodulated phase, and deriving recursive equations of the Kalman prediction model for the demodulated phase; and 4, judging whether a jump point exists in the actual demodulated phase, determining polarization states of lights if the jump point exists, and correcting the jump point when the polarization states of the lights are in polarization orthogonality by replacing the actual demodulated phase with a predicted phase value. The disclosure ensures the correctness of subsequent vibration-based signal processing.