A fiber optic sensor that simultaneously measures sound waves and pressure

Abstract

The invention discloses an optical fiber sensor capable of measuring acoustic wave and pressure simultaneously, comprising a monochromatic light source, an optical fiber coupler, a first single-mode optical fiber, a long-period optical fiber grating, an acoustic transduction film, a second single-mode optical fiber, a polarization maintaining optical fiber, a third single-mode optical fiber, a polarization controller, a fourth single-mode optical fiber, and a photoelectric detector. The polarization maintaining optical fiber is connected between a third port and a fourth port of the optical fiber coupler to form a closed-loop Sagnac interferometer. The long-period optical fiber grating is embedded into the interferometer by means of fusion welding and is fixed to the acoustic transduction film. The acoustic transduction film converts external acoustic wave into dynamic curvature modulation of the grating so as to change the light intensity at the loss peak. Lateral pressure acting on the polarization maintaining optical fiber leads to comb interference spectrum drift, and the monochromatic light source converts the spectrum drift into output light intensity change. The direct-current component of an intensity signal output by the device contains static lateral pressure information, and the alternating-current component contains acoustic wave information, so that the acoustic wave and pressure can be measured simultaneously.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to an acoustic wave-pressure dual-parameter optical fiber sensor based on an optical fiber Sagnac interferometer. Background technique [0002] In recent years, due to the continuous occurrence of natural disasters and safety accidents such as tsunamis, earthquakes, and mine disasters, acoustic wave sensing and pressure sensing have attracted more and more attention. Compared with traditional electrical or mechanical sensors, acoustic wave sensors and pressure sensors based on optical fiber technology have the advantages of small size, light weight, anti-electromagnetic interference, corrosion resistance, and easy networking and reuse. Accurate measurement of acoustic and pressure signals has important applications in many engineering applications, such as structural health monitoring, earthquake disaster early warning, pipeline leakage monitoring, etc. Si...

AI Technical Summary

Problems solved by technology

Because this method uses spectral demodulation, it is suitable for the simultaneous measurement of two static parameters, and it is difficult to apply to dynamic signals such as sound waves and vibrations.

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