Abstract: The present disclosure discloses a manufacturing method of an optical fiber chemical ratiometric sensor measurement system for measuring underwater dissolved oxygen concentration. The manufacturing method includes the steps of firstly, preparing a carrier substrate to obtain a solution A; then, preparing an oxygen sensitive dye to obtain a solution B; preparing a reference dye to obtain a solution C; mixing the solution A, the solution B and the solution C according to a ratio of 2:1:1 to obtain a composite sensitive dye; depositing the composite sensitive dye on one end face of a sensing optical fiber to prepare a fiber optic probe; establishing the optical fiber chemical ratiometric sensor measurement system, receiving the optical signal by a spectrometer as a fluorescence spectrum, and finally saving and processing fluorescence spectral data by computer software.

Abstract: The present invention discloses a residual pressure measurement system for a MEMS pressure sensor with an F-P cavity and method thereof, the measurement system includes a low-coherence light source, a 3 dB coupler, a MEMS pressure sensor, an air pressure chamber, a thermostat, a pressure control system, a cavity length demodulator, an acquisition card and a computer. The measurement method comprises: performing cavity length measurement by using the reflecting light by the pressure control system at two temperatures, respectively, so as to calibrate the MEMS pressure sensor and establish a relationship between the absolute phase of a monochromatic frequency and the external pressure; performing linear fitting to the two measurement data to obtain all the external pressure when the cavity length of two measurement data are equal to each other, and substituting the theoretical equation for calculation to obtain the residual pressure under the flat condition of the diaphragm.

Abstract: The present invention discloses a differential COTDR distributed acoustic sensing device based on heterogeneous double-sideband chirped-pulses of the invention, comprising a light source (1), a 1×2 polarization-maintaining optical-fiber coupler (2), a dual Mach-Zehnder electro-optical modulator (3), an arbitrary waveform generator (4), a first low noise microwave amplifier (5), a second low noise microwave amplifier (6), an electro-optical modulator bias control panel (7), a 1×2 optical-fiber coupler (8), an erbium-doped optical-fiber amplifier (9), an optical-fiber filter (10), an optical-fiber circulator (11), a sensing optical fiber (12), a tricyclic polarization controller (13), a 2×2 optical-fiber coupler (14), a balanced photoelectric detector (15), a data acquisition card (16) and a processing unit (17).

Abstract: The present invention discloses a Fiber Bragg Grating demodulation device with a suppressed fluctuation at a variable ambient temperature and a demodulation method. The device comprises a broadband light source (1), an optical attenuator (2), a tunable F-P filter (3), a first optical fiber isolator (41), an erbium-doped optical fiber amplifier (5), an optical fiber first-stage beam splitter (6), a first optical fiber second-stage beam splitter (71), optical fiber circulators (8), FBG sensor arrays (9), a first photoelectric detector array (161), an optical fiber gas cell (10), a second optical fiber second-stage beam splitter (72), an optical fiber F-P etalon (11), a notch filter (12), an optical fiber assisted interferometer (13), a data acquisition card (17) and a processor (18).

Abstract: The present invention discloses a residual pressure measurement system for a MEMS pressure sensor with an F-P cavity and method thereof, the measurement system includes a low-coherence light source, a 3 dB coupler, a MEMS pressure sensor, an air pressure chamber, a thermostat, a pressure control system, a cavity length demodulator, an acquisition card and a computer. The measurement method comprises: performing cavity length measurement by using the reflecting light by the pressure control system at two temperatures, respectively, so as to calibrate the MEMS pressure sensor and establish a relationship between the absolute phase of a monochromatic frequency and the external pressure; performing linear fitting to the two measurement data to obtain all the external pressure when the cavity length of two measurement data are equal to each other, and substituting the theoretical equation for calculation to obtain the residual pressure under the flat condition of the diaphragm.

Abstract: Fiber optical Fabry-Perot flow test device with local bending diversion structure, having an inlet flange, a test tube and an outlet flange, with both a fiber optical Fabry-Perot pressure sensor at high-pressure-side and a fiber optical Fabry-Perot pressure sensor at low-pressure-side, which are fixedly connected to the test tube through an auxiliary connecting device.

Abstract: The present invention discloses a distributed device for simultaneously measuring strain and temperature based on optical frequency domain reflection, comprising a tunable laser, a 1:99 beam splitter, a main interferometer system, a light source phase monitoring system based on an auxiliary interferometer, an acquisition device and a computer processing unit, wherein the main interferometer system comprises two Mach-Zehnder interferometers, and two optical fibers having different cladding diameters are arranged in parallel as sensing fibers. Due to the difference in temperature and strain coefficients of optical fibers of the same diameter, the temperature and strain values during changing the temperature and strain simultaneously can be obtained by matrix operation, thereby achieving an effect of eliminating cross sensitivity of temperature and strain sensing in optical frequency domain reflection.

Abstract: A distributed optical fiber disturbance positioning system based on the asymmetric dual Mach-Zehnder interference, unlike traditional dual Mach-Zehnder distributed optical fiber disturbance sensing system, the present invention adopts two narrow-bandwidth optical sources (1a, 1b) and adopts corresponding DWDM (3a, 3b) before the detector (4a, 4b) to filter the backscatter noise of the optical fiber, and can solve the problems of having too low SNR due to backscatter influence when the sensing distance is long. The present invention also provides a positioning method for applying the system, which obtains the TFD of the disturbance frame signals by using the time-frequency analysis method based on the short-term average frequency, and takes the points near the point of maximum frequency as the effective signal segment for performing cross-correlation time delay estimation, thus obtaining the delay, and the disturbance position.

Abstract: The present invention discloses a Fiber Bragg Grating demodulation device with a suppressed fluctuation at a variable ambient temperature and a demodulation method. The device comprises a broadband light source (1), an optical attenuator (2), a tunable F-P filter (3), a first optical fiber isolator (41), an erbium-doped optical fiber amplifier (5), an optical fiber first-stage beam splitter (6), a first optical fiber second-stage beam splitter (71), optical fiber circulators (8), FBG sensor arrays (9), a first photoelectric detector array (161), an optical fiber gas cell (10), a second optical fiber second-stage beam splitter (72), an optical fiber F-P etalon (11), a notch filter (12), an optical fiber assisted interferometer (13), a data acquisition card (17) and a processor (18).

Abstract: The present invention discloses an optical fiber laying method by using Archimedes spiral in optical frequency domain reflection, wherein the optical fiber laying method comprises the following steps: performing two measurements continuously via a two-dimensional strain sensing device, and performing cross-correlation operation on the two one-dimensional information of the local distance domain, and obtaining the strain variation of the one-dimensional information corresponding to the two measurements from the obtained cross-correlation information; deriving the two-dimensional angle information and curvature radius information of the plane to be measured corresponding to one-dimensional information in the local distance domain based on Archimedes spiral formula; deriving the position coordinates corresponding to the two-dimensional plane based on the curvature radius information and two-dimensional angle information; corresponding the strain variation of the one-dimensional information to the position coordi

Abstract: The present invention discloses a fiber optical Fabry-Perot flow test device with local bending diversion structure, comprising an inlet flange, a test tube and an outlet flange, wherein a fiber optical Fabry-Perot pressure sensor at high-pressure-side is connected to a first circulator which is connected to a first light source and a first optical signal demodulation system, and the first optical signal demodulation system being connected to a first linear array CCD camera; and, a fiber optical Fabry-Perot pressure sensor at low-pressure-side is connected to a second circulator which is connected to a second light source and a second optical signal demodulation system, the second optical signal demodulation system being connected to a second linear array CCD camera, both the first linear array CCD camera and the second linear array CCD camera being connected to a signal conditioning and acquisition circuit which is connected to a data processing unit.

Abstract: The present invention discloses a distributed device for simultaneously measuring strain and temperature based on optical frequency domain reflection, comprising a tunable laser, a 1:99 beam splitter, a main interferometer system, a light source phase monitoring system based on an auxiliary interferometer, an acquisition device and a computer processing unit, wherein the main interferometer system comprises two Mach-Zehnder interferometers, and two optical fibers having different cladding diameters are arranged in parallel as sensing fibers. Due to the difference in temperature and strain coefficients of optical fibers of the same diameter, the temperature and strain values during changing the temperature and strain simultaneously can be obtained by matrix operation, thereby achieving an effect of eliminating cross sensitivity of temperature and strain sensing in optical frequency domain reflection.

Abstract: A distributed optical fiber disturbance positioning system based on the asymmetric dual Mach-Zehnder interference, unlike traditional dual Mach-Zehnder distributed optical fiber disturbance sensing system, the present invention adopts two narrow-bandwidth optical sources (1a, 1b) and adopts corresponding DWDM (3a, 3b) before the detector (4a, 4b) to filter the backscatter noise of the optical fiber, and can solve the problems of having too low SNR due to backscatter influence when the sensing distance is long. The present invention also provides a positioning method for applying the system, which obtains the TFD of the disturbance frame signals by using the time-frequency analysis method based on the short-term average frequency, and takes the points near the point of maximum frequency as the effective signal segment for performing cross-correlation time delay estimation, thus obtaining the delay, and the disturbance position.

Abstract: The present invention discloses a high-resolution polarized low-coherence interference pressure measurement device and method, which comprise a broadband light source (1), an optical fiber coupler (2), an optical fiber Fabry-Perot sensor (3), a collimating lens (4), a polarizer (5), a birefringence wedge (6) having a spatial dip angle, an analyzer (7), a matrix camera (8), and a signal processing unit (9), which are successively provided from an input end to an output end; wherein light emitted from the broadband light source (1) passes through the optical fiber coupler (2) and arrives at the optical fiber Fabry-Perot sensor (3), and returned light emitted from the optical fiber Fabry-Perot sensor (3) is led into a demodulation interferometer; a change in pressure is transformed into a change in length of a Fabry-Perot cavity by the optical fiber Fabry-Perot sensor (3), and different pressures correspond to different lengths of the Fabry-Perot cavity; the collimating lens (4), the polarizer (5), the birefring

Abstract: This invention relates to a distributed disturbance sensing device based on polarization sensitive optical frequency domain reflectometry (OFDR) and the related demodulation thereof. The device, adopting OFDR, polarization controlling and analysis techniques, consists of a ultra-narrow linewidth tunable laser source module, polarization generating and polarization splitting balanced detecting module, laser source optical frequency and phase monitoring module, high-speed optical switch and so on to establish a large-scale and long-distance optical sensing network. The demodulation method consists of analysis the polarization information from sensing optical fiber, the method of suppressing and compensating of the non-linear optical frequency and the laser phase noise, super-resolution analyzing, advanced denoising method and the polarization information analysis method based on Jones and Mueller's matrices using distributed wave plate model of optical fiber.

Abstract: The present invention relates to a high stable fiber fabry-perot pressure sensor with glue-free packing and its fabrication method. The sensor includes a sensor head, a sensor body with a through-hole in the axial direction and a optical fiber. The sensor head is a 4-layer structure, which includes the first silicon wafer, the first Pyrex glass wafer, the second silicon wafer and the second Pyrex glass wafer. The rear surface of the first silicon wafer forms the first reflecting surface of the fabry-perot (F-P) cavity, and the second silicon wafer provides the second reflecting surface for the F-P cavity. The second Pyrex glass wafer is welded together with the sensor body. The optical fiber is fixed in the sensor body by a CO2 laser welding to achieve the glue-free packing. When the external pressure is applied to deform the first layer silicon wafer, the F-P cavity length will change.

Abstract: Swing-style demodulation device for measuring displacement information, including (1) a broadband light source, (2) an optical circulator, (3) GRIN lens, (4) a fixed mirror on an object under test, (5) a collimating device, (6) a rotating mirror, (7) f-? lens, (8) a polarizer, (9) a narrow strip shaped birefringent wedge, (10) a polarization analyzer, and (11) a signal acquisition system.

Abstract: Disclosed is a multi-band multiplexing intra-cavity gas sensing system and method. The system consists of a laser resonant cavity subsystem, a gas sensing subsystem and a detection-demodulation subsystem. The laser resonant cavity subsystem consists of the first beam splitter, two ways of gain paths composed of a pump light source, a wavelength division multiplexer, a rare earth doped fiber, an optical isolator and a tunable optical attenuator, a beam combiner and an F-P tunable optical filter. The gas sensing subsystem consists of a gas cell and an optical reflective mirror. The detection-demodulation subsystem consists of an optical coupler, the second beam splitter, two optical detectors, a data acquisition module and a computer. In this invention, different rare-earth doped fibers are multiplexing into one system, in order to cover more maser bands of different rare earth, which greatly expands the scanning range of wavelength, and is capable of detecting various gases simultaneously.

Abstract: The present invention relates to a high stable fiber fabry-perot pressure sensor with glue-free packing and its fabrication method. The sensor includes a sensor head, a sensor body with a through-hole in the axial direction and a optical fiber. The sensor head is a 4-layer structure, which includes the first silicon wafer, the first Pyrex glass wafer, the second silicon wafer and the second Pyrex glass wafer. The rear surface of the first silicon wafer forms the first reflecting surface of the fabry-perot (F-P) cavity, and the second silicon wafer provides the second reflecting surface for the F-P cavity. The second Pyrex glass wafer is welded together with the sensor body. The optical fiber is fixed in the sensor body by a CO2 laser welding to achieve the glue-free packing When the external pressure is applied to deform the first layer silicon wafer, the F-P cavity length will change.

Abstract: This invention relates to a distributed disturbance sensing device based on polarization sensitive optical frequency domain reflectometry (OFDR) and the related demodulation thereof. The device, adopting OFDR, polarization controlling and analysis techniques, consists of a ultra-narrow linewidth tunable laser source module, polarization generating and polarization splitting balanced detecting module, laser source optical frequency and phase monitoring module, high-speed optical switch and so on to establish a large-scale and long-distance optical sensing network. The demodulation method consists of analysis the polarization information from sensing optical fiber, the method of suppressing and compensating of the non-linear optical frequency and the laser phase noise, super-resolution analyzing, advanced denoising method and the polarization information analysis method based on Jones and Mueller's matrices using distributed wave plate model of optical fiber.