A Weak Reflection FBG-Fizeau Sensing Device

Abstract

The invention provides a weak reflection-FIZEAU sensing device comprising a sensing end used for reflecting multiple scanning laser with different wavelengths and a demodulating end used for demodulating optical signals reflected by the sensing end to obtain a measurement result, wherein the sensing end comprises an optical circulator and a polarization maintaining optical fiber, weak reflection FBG-FIZEAU optical fiber resonant cavities in the same as the scanning laser wavelengths are arranged in each segment of polarization maintaining optical fiber, and each segment of polarization maintaining optical fiber is correspondingly provided with a serially connected optical circulator; and the demodulating end comprises a multi-wavelength scanning laser, a polarization controller, a linear polarizer, an optical switch, a wavelength division multiplexer, a photoelectric detector and a signal analysis module. Compared with the prior art, high-precision demodulation is realized by measuring the stripe contrast of sensing signals, the requirements on the performance of the wavelength scanning laser are not high, and a reference sensor is omitted, so that the system is simple, and the cost is low.

Description

technical field [0001] The invention relates to an optical fiber sensing device, in particular to a weak anti-FIZEAU sensing device based on fringe contrast demodulation. Background technique [0002] Compared with electrical sensors, optical fiber sensors have the advantages of small size, suitable for harsh environments, high reliability, and easy long-distance communication networking, etc., and have been widely used in large-scale engineering and building structure health monitoring. However, the sensing accuracy of the fiber optic sensor is affected by various demodulation factors such as the jitter of the light source power, the drift of the wavelength, and the drift of the wavelength calibration module. Taking a typical fiber Bragg grating sensor as an example, the linearity of the wavelength scanning filter and the degradation of wavelength repeatability will greatly reduce the detection accuracy of the Bragg wavelength. [0003] The existing solutions to improve th...

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Problems solved by technology

[0004] Among them, the DFB fiber optic sensor will reduce the multiplexing capacity due to the absorption of the active fiber and the loss of the melting point. In addition, the accurate measurement of the wavelength shift of the DFB still depends on a high-precision demodulation system, so the system cost is high.

[0005] The sensor is designed with a special optical fiber structure. Due to the damage of the optical fiber waveguide structure, the loss is large and the consistency is low, so it is difficult to achieve multiplexing.

[0006] The FBG peak-finding algorithm is easily affected by the wavelength power drift of the light source, and has high requirements on the stability of the light source and wavelength scanning module, so the system cost is high

[0007] The demodulation technology based on PDH frequency locking requires a complex error signal calculation module, and the system is relatively complex. In addition, in order to compensate for the instability of the laser, a reference sensor needs to be used for compensation, which is not conducive to the miniaturization and packaging of the sensor.

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