High resolution sensing system measuring beat-length and strain of polarization maintaining optical fiber based on optical frequency domain reflectometer (OFDR) system

A polarization-maintaining optical fiber and sensing system technology, which can be applied in the direction of measurement, measurement device, and optical device by measuring the change of optical properties of materials when they are stressed, and can solve the instability of optical fiber output polarization state changes in time and space. It can avoid the limitation of optical pulse width and data sampling rate, fast signal processing and demodulation, and improve the sensitivity and dynamic range.

Inactive Publication Date: 2013-05-08
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Description
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  • Application Information

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Problems solved by technology

However, ordinary optical fibers used in distributed optical fiber sensors are susceptible to birefringence disturbances caused by external factors such as bending, pressure, torsion, electromagnetic fields, and temperature. Unstable, so it is very difficult to use the polarization state or phase performance in the fiber

Method used

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  • High resolution sensing system measuring beat-length and strain of polarization maintaining optical fiber based on optical frequency domain reflectometer (OFDR) system
  • High resolution sensing system measuring beat-length and strain of polarization maintaining optical fiber based on optical frequency domain reflectometer (OFDR) system
  • High resolution sensing system measuring beat-length and strain of polarization maintaining optical fiber based on optical frequency domain reflectometer (OFDR) system

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Embodiment 1

[0028] Such as figure 1 As shown, it is a schematic diagram of a high-resolution sensing system based on the OFDR system and Michelson interferometric structure to measure the beat length and stress or strain of polarization-maintaining optical fiber. It can be adjusted according to the measurement distance and the spatial resolution. The light generated by the linearly swept narrow-linewidth light source is converted into linearly polarized light by the fiber polarizer and injected into the polarization-maintaining fiber coupler; one output end of the fiber coupler is connected to the polarization-maintaining fiber used for strain testing, and the other end is connected to A section of polarization-maintaining fiber is used as a reference arm, and a mirror is attached to the end of the reference arm.

Embodiment 2

[0030] Such as figure 2 As shown, it is a schematic diagram of a high-resolution sensing system based on the OFDR system and the MZ interferometric structure using single-ended detection to measure the beat length and stress or strain of polarization-maintaining fibers. A section of polarization-maintaining fiber connected to the first polarization-maintaining fiber coupler as a reference arm is connected to the output end of the circulator through a second polarization-maintaining fiber coupler to generate interference, and a detector is used to detect the interference signal.

Embodiment 3

[0032] image 3 Shown is a schematic diagram of the dual-way balanced detection structure. When a point on the test polarization-maintaining fiber is strained, the beat length of this position will change, and the amount of change is proportional to the strain. At the same time, the Rayleigh backscattering signal generated at this position will propagate to the polarization-maintaining fiber coupler to mix and interfere with the optical signal returned by the reference arm, and output a beat frequency signal. The frequency of the beat frequency signal reflects the stress or strain position, and the magnitude of the beat frequency is the magnitude of the optical power at that point. The beat length at this time can be obtained by detecting the cycle of a certain polarization state optical power change, and finally the corresponding stress or strain can be obtained through the mapping model of the beat length and the change signal.

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Abstract

The invention discloses a high resolution sensing system measuring beat-length and strain of a polarization maintaining optical fiber based on an optical frequency domain reflectometer (OFDR) system. The high resolution sensing system measuring the beat-length and the strain of the polarization maintaining optical fiber based on the OFDR system is characterized by comprising a linear frequency sweeping narrow line width light source, a polarizer, an interference system, a photoelectric detector, an optical heterodyne receiver and a signal processing system, wherein light produced by the linear frequency sweeping narrow line width light source is transformed to linearly polarized light through the polarizer and the linearly polarized light is injected to the interference system, the interference system is connected with the optical heterodyne receiver through the photoelectric detector, and the signal processing system is connected with the optical heterodyne receiver. The system is simple in structure, all-fiber-optical and controllable in linear frequency sweeping of a laser. By means of optical frequency domain detection, the problem that spatial resolution in time domain detection is limited by the optical pulse width and the data sampling rate is solved, high spatial resolution is obtained, and sensibility of the system can be improved and the dynamic range of the system can be enlarged through optical heterodyne detection.

Description

technical field [0001] The invention belongs to the technical field of distributed optical fiber sensors, in particular to a sensing system for measuring the beat length and stress or strain of a polarization-maintaining optical fiber by using an OFDR system. Background technique [0002] With the improvement of the transmission rate of the communication system and the development of advanced fiber optic sensor devices such as fiber optic gyroscopes and fiber optic hydrophones, in the interferometric fiber optic sensor based on optical coherent detection, the direction of the polarization state is controlled to remain unchanged, and the coherent signal-to-noise ratio is improved. , to achieve high-precision measurement of physical quantities has become very urgent. The stress measurement of optical fiber usually adopts the quarter-wave plate method, which has been widely used in the stress measurement of ordinary optical glass and crystal. However, ordinary optical fibers u...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/16G01L1/24
Inventor 欧中华陈玉李剑锋岳慧敏刘永代志勇
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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