Dual wavelength regression analysis-based optical fiber vibration sensor phase demodulation device and method

Abstract

The invention relates to a dual wavelength regression analysis-based optical fiber vibration sensor phase demodulation device, which is characterized by comprising a first narrowband laser, a second narrowband laser, a taper wavelength division multiplexer, a coupler, a digitally-controlled dimming delay line, an annular piezoelectric ceramic tube, a three-third coupler, a first taper wavelength division demultiplexer, a second taper wavelength division demultiplexer, a third taper wavelength division demultiplexer and a multi-channel data acquisition card, wherein the outer circle of the annular piezoelectric ceramic tube is uniformly wound with the vibration sensing optical fiber; and the annular piezoelectric ceramic tube can be telescopic periodically under driving of control signals.A dual-wavelength Mach-Zehnder interferometer and a three-third coupler digital phase demodulation technique are used, a dual wavelength regression analysis phase unwrapping principle is adopted, thepi phase limitation principle in the traditional phase unwrapping can be overcome in principle, instantaneous large-scale phase changes caused by actual strong vibration signals are tracked precisely,and a good and single-wavelength interferometry-consistent signal-to-noise ratio level is achieved.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a phase demodulation device and method for an optical fiber vibration sensor based on dual-wavelength regression analysis. Background technique [0002] Optical fiber has outstanding advantages such as small size, light weight, intrinsic passive safety, etc., and many sensors such as fiber optic accelerometers, fiber optic hydrophones, and fiber optic gyroscopes using this as a medium have developed rapidly. Among them, fiber optic vibration sensors are being studied in depth as an important part of the new generation of vibration sensing systems, and are expected to play an irreplaceable role in geological disaster early warning, hydroacoustic sonar monitoring and other fields. Among various optical fiber vibration sensing forms including intensity, frequency, wavelength, polarization state modulation, etc., the phase modulation type has the highest sensitivity, an...

AI Technical Summary

Problems solved by technology

At present, most interferometric fiber optic vibration sensors still use single-wavelength interferometric phase demodulation technology. The limitation of this technology is that the optical path difference between two adjacent points cannot change more than half of the wavelength value, so a high sampling rate is required. This has high requirements on the data acquisition system, especially in the long-distance distributed optical fiber vibration sensing system with thousands of fiber grating sensors in series, which greatly increases the load on the phase demodulation system

Subsequently, J.Gass et al. proposed a synthetic wavelength phase demodulation technique (Gass J, Dakoff A, KimM K.Phase imaging without 2πambiguity by multiwavelength digital holography[J]. Optics Letters,2003,28(13):1141-3 .), that is, two sets of interference signals are obtained by using two different wavelength lasers, and the phase information of the synthesized wavelength is obtained. Since the noise is proportional to the wavelength, the phase noise obtained from the synthesized wavelength is relatively large

Therefore, Zhang Bing et al. improved on this basis (Zhang Bing, Wang Kuiru, Yan Pingping, et al. Interferometric phase unwrapping method based on dual wavelength and 3×3 coupler[J]. Acta Optics Sinica, 2018 ,38(4):224-231.), so that the signal-to-noise ratio level reaches the level of a single wavelength, but the measurement of the synthesized wavelength is still limited by the traditional π phase principle, and it is also not suitable for such things as railroad tracks, perimeter security, Applications such as optical fiber hydrophones that require the measurement of ultra-large amplitude vibration signals

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