Tianjin University

Sprint Communications Comapny L.p.

Junfeng Jiang

Kun Liu

Tiegen Liu

Shuang Wang

Zhenyang Ding

Xuezhi Zhang

Jinde Yin

Rongqing Hui

Douglas Lew Richards

Stephen Arthur Oliva

Yu Liu

Shaohua Wang

Qiliang Chu

Guanhua Liang

Chang He

Miao Tian

Huijia Yang

Zhichen Li

Jinling Yan

Weihang Zhang

Dingjie Li

Di Yang

Xiao Liang

Xue Wang

Chuanjun Zang

Yang Du

Mengnan Xiao

Wenjie Chen

Tianjiao Chai

Zhexi Xu

Dongdong Ju

Renwei Xie

Chunyu Ma

Zhe Ma

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 (), a 1×2 polarization-maintaining optical-fiber coupler (), a dual Mach-Zehnder electro-optical modulator (), an arbitrary waveform generator (), a first low noise microwave amplifier (), a second low noise microwave amplifier (), an electro-optical modulator bias control panel (), a 1×2 optical-fiber coupler (), an erbium-doped optical-fiber amplifier (), an optical-fiber filter (), an optical-fiber circulator (), a sensing optical fiber (), a tricyclic polarization controller (), a 2×2 optical-fiber coupler (), a balanced photoelectric detector (), a data acquisition card () and a processing unit (). The present invention combines heterogeneous double-sideband chirped-pulse modulation and coherent light time-domain reflection technology, so as to double the sensitivity of the to-be-measured acoustic wave signal and to suppress common-mode noise, and further improves SNR.

Differential COTDR distributed acoustic sensing device and method based on heterogeneous double-sideband chirped-pulses

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.

Residual pressure measurement system for Fabry-Perot cavity of optical MEMS pressure sensor and method thereof

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 (), an optical attenuator (), a tunable F-P filter (), a first optical fiber isolator (), an erbium-doped optical fiber amplifier (), an optical fiber first-stage beam splitter (), a first optical fiber second-stage beam splitter (), optical fiber circulators (), FBG sensor arrays (), a first photoelectric detector array (), an optical fiber gas cell (), a second optical fiber second-stage beam splitter (), an optical fiber F-P etalon (), a notch filter (), an optical fiber assisted interferometer (), a data acquisition card () and a processor ().

Fiber Bragg Grating demodulation device capable of supressing fluctuations at variable ambient temperature and demodulation method thereof

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.

Fiber optical fabry-perot flow test device and test method with local bending diversion structure

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.

Distributed measuring device and method for simultaneously measuring strain and temperature based on optical frequency domain reflection

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 () and adopts corresponding DWDM () before the detector () 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. The method of the invention positions the asymmetric disturbance frame signals in the systems, thus having a high positioning accuracy and reliability.

Distributed optical fiber disturbance positioning system based on the asymmetric dual Mach-Zehnder interference, and positioning method thereof

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.

Distributed disturbance sensing device and the related demodulation method based on polarization sensitive optical frequency domain reflectometry

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 COlaser 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. When a broad band source is used, the variation of the cavity length can be obtained by collecting the reflection spectrum or low-coherence interference fringe of the sensor, thus the pressure information can be obtained. The structure of the invention can effectively eliminate the affect of environmental factors, such as temperature and humidity, and greatly promoting the measuring accuracy.

High stable fiber fabry-perot pressure sensor with glue-free packing and its fabrication method

Swing-style demodulation device for measuring displacement information, including () a broadband light source, () an optical circulator, () GRIN lens, () a fixed mirror on an object under test, () a collimating device, () a rotating mirror, () f-&#x3b8; lens, () a polarizer, () a narrow strip shaped birefringent wedge, () a polarization analyzer, and () a signal acquisition system.

Swing-style and high signal-to-noise ratio demodulation devices and corresponding demodulation method for the measurement of low coherence interference displacement

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. New gain paths can be added to the system, to further expand the scanning range of wavelength. Hence, the present invention has strong expandability.

Multi-band multiplexing intra-cavity gas sensing system and method

A method is provided for measuring polarization dependent loss in an optical transmission system. In the method, a first optical signal is generated, and a polarization of the first optical signal is altered over time. The first optical signal is combined with a second optical signal from the optical transmission system to yield a combined optical signal, which is coherently detected to yield a radio frequency signal. A power of the radio frequency signal is measured. The measured power of the radio frequency signal is processed to generate an indication of the polarization dependent loss of the optical transmission system.

Measurement of polarization dependent loss in an optical transmission system

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Tianjin, China

Junfeng Jiang