Optical fiber vector hydrophone for realizing common-mode noise self-suppression and sensing method of optical fiber vector hydrophone

Abstract

The invention discloses an optical fiber vector hydrophone for realizing common-mode noise self-suppression and a sensing method of the optical fiber vector hydrophone. According to the hydrophone, seven equally-spaced optical gratings are engraved on a polarization-maintaining sensing fiber; the polarization-maintaining sensing fiber is sequentially wound on elastic cylinders from the first elastic cylinder to the sixth elastic cylinder which are arranged on a mass block in a mutually-perpendicular manner, and the optical gratings are located on the mass block; and vibration vector measurement in mutually-perpendicular dimensions is realized on the basis of a double-pulse scheme, and common-mode noises can be eliminated at the absence of an additional reference accelerometer during the measurement process on the basis of the special design of the structure of the hydrophone itself. The optical fiber vector hydrophone of the present invention, not requiring other additional optical passive devices, has the advantage of structural simplicity. By means of a weak reflection fiber Bragg grating-based special push-pull structure of the hydrophone itself, the suppression of the common-mode noises of the sensing system can be realized with no additional reference accelerometers used, and therefore, the cost and size of the sensing system can be reduced. The hydrophone has more obviousadvantages in large-scale quasi-distributed monitoring.

Description

technical field [0001] The invention relates to an optical fiber hydrophone, in particular to an optical fiber vector hydrophone capable of self-suppression of common-mode noise and a sensing method thereof. Background technique [0002] Acoustic waves are a kind of mechanical waves. Compared with electromagnetic waves such as light waves and radio waves, sound waves can achieve long-distance transmission with low attenuation in water, so they are an important medium for humans to obtain effective information on marine stratigraphic structures. As an important acoustic measurement device for collecting and receiving underwater acoustic wave information, hydrophones are widely used in the fields of submarine oil and gas reservoir exploration, submarine microseismic monitoring, and military anti-submarine. Compared with sensing electronic hydrophones, optical fiber hydrophones based on optical fiber sensing technology have the advantages of anti-electromagnetic interference, h...

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Problems solved by technology

[0006] At present, in the optical fiber vector hydrophone, the method of suppressing common-mode noise by introducing an additional reference accelerometer into the sensing system mainly has the following defects: (1) The common-mode noise eliminated by traditional means mainly comes from the front-end system, such as Lasers, acousto-optic modulators, etc., but the noise introduced to the vector hydrophone itself by the external environment cannot be suppressed; (2) the reference accelerometer still has a certain sensitivity to underwater vibration signals under normal circumstances, so the vector hydrophone The method of phase subtraction from the reference accelerometer will filter out some useful underwater vibration signals; (3) The introduction of additional reference accelerometers will increase the cost and volume of the sensing system

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