CN111256807B - A small-size interference-type high-frequency fiber optic hydrophone based on a folded air cavity - Google Patents

Abstract

Translated fromChinese

本发明涉及光纤传感领域，具体涉及一种基于折叠空气腔的小尺寸干涉型高频光纤水听器，包括4个可嵌套安装的薄壁空心圆筒：带第一光纤缠绕区与第一支撑结构的第一薄壁空心圆筒，带第二光纤缠绕区与第二支撑结构的第二薄壁空心圆筒，带第三光纤缠绕区与第三支撑结构的第三薄壁空心圆筒，带第四光纤缠绕区与第四支撑结构的第四薄壁空心圆筒，以及光纤干涉仪；本发明具有以下有益效果：首先在不减小光纤缠绕面积，降低光纤干涉仪两臂长度的前提下，极大减小了光纤水听器横向尺寸，可提高光纤水听器高频应用性能；其次，通过多层嵌套、折叠式空气腔的结构设计，实现了更小的半径和横向尺寸，可提高机械结构谐振频率，进而优化水听器频率响应特性。

The invention relates to the field of optical fiber sensing, in particular to a small-size interference type high-frequency optical fiber hydrophone based on a folded air cavity, comprising four thin-walled hollow cylinders that can be nested and installed: A first thin-walled hollow cylinder with a support structure, a second thin-walled hollow cylinder with a second fiber winding area and a second support structure, and a third thin-walled hollow circle with a third fiber winding area and a third support structure cylinder, a fourth thin-walled hollow cylinder with a fourth optical fiber winding area and a fourth supporting structure, and an optical fiber interferometer; the present invention has the following beneficial effects: first, the length of the two arms of the optical fiber interferometer is reduced without reducing the optical fiber winding area On the premise, the lateral size of the fiber optic hydrophone is greatly reduced, which can improve the high-frequency application performance of the fiber optic hydrophone; The lateral dimension can increase the resonant frequency of the mechanical structure, thereby optimizing the frequency response characteristics of the hydrophone.

Description

Translated fromChinese

一种基于折叠空气腔的小尺寸干涉型高频光纤水听器A small-size interference-type high-frequency fiber optic hydrophone based on a folded air cavity

技术领域technical field

本发明涉及光纤传感领域，具体涉及一种基于折叠空气腔的小尺寸干涉型高频光纤水听器，特别适用于高频水声信号探测应用。The invention relates to the field of optical fiber sensing, in particular to a small-size interference type high-frequency optical fiber hydrophone based on a folded air cavity, which is particularly suitable for high-frequency underwater acoustic signal detection applications.

背景技术Background technique

光纤水听器是基于光纤传感与光电子技术的一种新型水听器，具有灵敏度高、频带响应宽、抗电磁干扰、耐恶劣环境、结构轻巧、易于遥测和大规模成阵等特点，主要用于海洋声学环境中的声传播、噪声、混响、海底声学特性、目标声学特性等的探测，在海洋资源勘探、海底地质勘查、海底观测网、海洋国土安全等领域具有广泛应用前景。Optical fiber hydrophone is a new type of hydrophone based on optical fiber sensing and optoelectronic technology. It is used for the detection of sound propagation, noise, reverberation, seabed acoustic characteristics, target acoustic characteristics, etc. in the marine acoustic environment.

目前，光纤水听器的技术方案主要包括光纤光栅型、光纤激光型以及双臂干涉型三种，其中双臂干涉型光纤水听器方案最为成熟，应用也最为广泛。其基本原理为：高稳定性窄线宽激光器发出的激光经3dB耦合器一分为二，分别进入光纤干涉仪的两臂；光纤干涉仪两臂缠绕在增敏结构或材料上，外界声压信号引起增敏结构或材料发生形变，引起光纤干涉仪两臂长度发生相对变化，进而导致两臂间传输的激光光束产生随相对长度变化的相位差；干涉仪输出光强随两臂间相对相位变化而变化，通过对光纤干涉仪干涉光强的精确探测，可解算出外界声压信号。At present, the technical solutions of fiber optic hydrophone mainly include fiber grating type, fiber laser type and double-arm interference type. Among them, the double-arm interference type fiber optic hydrophone solution is the most mature and widely used. The basic principle is: the laser light emitted by the high-stability narrow linewidth laser is divided into two parts by the 3dB coupler and enters the two arms of the fiber interferometer respectively; the two arms of the fiber interferometer are wound on the sensitizing structure or material, and the external sound pressure The signal causes the deformation of the sensitizing structure or material, which causes the relative length of the two arms of the fiber interferometer to change, which in turn causes the laser beam transmitted between the two arms to produce a phase difference that varies with the relative length; the output light intensity of the interferometer varies with the relative phase between the two arms. Through the accurate detection of the interference light intensity of the fiber optic interferometer, the external sound pressure signal can be calculated.

近年来，人们发明了多种结构来提高干涉型光纤水听器的性能以及不同应用背景下的适装性。文献报道中典型结果包括：Wen等人(High-sensitivity fiber-opticultrasound sensors for medical imaging applications[J]，Ultra-sonic Imaging，1998，20(2)：103-112)较早采用光纤缠绕于聚乙烯圆柱的方式提高水听器灵敏度，实现水中相移灵敏度45mrad/kPa，响应带宽达4MHz；Gallego等人(High-sensitivity ultrasoundinterferometric single-mode polymer optical fiber sensors for biomedicalapplications[J]，Optics Letters，2009，34(12)：1807–1809)基于单模聚合物光纤实现马-曾干涉型光纤传感，得益于聚合物光纤相比传统熔融石英光纤更低的杨氏模量，光纤在水中与声场耦合更好，实现相移灵敏度1.31mrad/kPa，响应带宽高达5MHz。国防科技大学张学亮等人(Sensing system with Michelson-type fiber optical interferometerbased on single FBG reflector[J].Chinese Optics Letters，2011，9(11)：110601)采用光纤布拉格光栅(fiber Bragg grating,FBG)作为迈克尔逊干涉仪的反射器件，测得频率响应范围100Hz～2kHz内波动低于0.3dB。科研人员从增敏结构设计、材料优选、核心器件改进等多个方面进行了较为系统的研究，将光纤水听器的性能指标大幅提高，最大程度释放了干涉型光纤水听器的应用潜能。在提高光纤水听器不同应用背景下的适装性方面，科研工程人员提出了多种不同设计。中国实用新型专利“干涉型光纤水听器”(CN 2729667Y)、中国实用新型专利“一种推挽式光纤水听器”(CN 202041279U)、中国发明专利申请“一种含空气腔的芯轴型光纤水听器”(申请号201711370586.0，公开日2018-06-01)、中国发明专利申请“一种深海用光纤水听器”(申请号201711447729.3，公开日2018-04-13)、中国发明专利申请“一种光纤水听器探头封装结构及封装方法”(申请号201811104270.1，公开日2019-01-11)从光纤水听器探头的传感结构优化及封装方式选择上提出了很好的思路。In recent years, various structures have been invented to improve the performance of interferometric fiber optic hydrophones and their suitability in different application contexts. Typical results reported in the literature include: Wen et al. (High-sensitivity fiber-opticultrasound sensors for medical imaging applications [J], Ultra-sonic Imaging, 1998, 20(2): 103-112) earlier used optical fibers wound on polyethylene The cylindrical method improves the sensitivity of the hydrophone, achieving a phase shift sensitivity of 45mrad/kPa in water and a response bandwidth of 4MHz; Gallego et al. (High-sensitivity ultrasoundinterferometric single-mode polymer optical fiber sensors for biomedical applications[J], Optics Letters, 2009, 34 (12): 1807–1809) Based on single-mode polymer fiber to realize Ma-Zeng interferometric fiber sensing, thanks to the lower Young's modulus of polymer fiber than traditional fused silica fiber, the fiber is coupled with the acoustic field in water Better yet, achieve a phase shift sensitivity of 1.31mrad/kPa and a response bandwidth of up to 5MHz. Zhang Xueliang from National University of Defense Technology (Sensing system with Michelson-type fiber optical interferometer based on single FBG reflector [J]. Chinese Optics Letters, 2011, 9(11): 110601) used fiber Bragg grating (FBG) as the The reflective device of the Sonder interferometer measures less than 0.3dB within the frequency response range of 100Hz to 2kHz. Researchers have carried out systematic research on the design of sensitization structure, material selection, and improvement of core devices, greatly improving the performance indicators of fiber optic hydrophones, and releasing the application potential of interferometric fiber optic hydrophones to the greatest extent. In terms of improving the suitability of fiber optic hydrophones under different application backgrounds, scientific research engineers have proposed a variety of different designs. Chinese utility model patent "Interference Fiber Optic Hydrophone" (CN 2729667Y), Chinese Utility Model Patent "A Push-Pull Fiber Optic Hydrophone" (CN 202041279U), Chinese Invention Patent Application "A Mandrel Containing an Air Cavity" Type Fiber Optic Hydrophone" (Application No. 201711370586.0, published on 2018-06-01), Chinese Invention Patent Application "An Optical Fiber Hydrophone for Deep Sea" (Application No. 201711447729.3, published on 2018-04-13), Chinese Invention The patent application "An Optical Fiber Hydrophone Probe Packaging Structure and Packaging Method" (Application No. 201811104270.1, published on 2019-01-11) proposes a good solution from the optimization of the sensing structure and the selection of the packaging method of the optical fiber hydrophone probe. ideas.

遗憾的是，现有干涉型光纤水听器技术在面临高频水声信号探测应用时仍存在一些共性问题。首先，为保证灵敏度达到要求，需提高干涉仪两臂长度，进而导致光纤缠绕区宽度增加，水听器探头横向尺寸过大，不适合高频探测应用。以水声通信信号探测为例，一般要求水听器响应频率至少达到30kHz，海水中典型波速为1500m/s，因此声波波长约为5cm。为避免光纤水听器探头声压响应产生方向性，一般要求光纤水听器探头尺寸远小于声波波长，即探头尺寸需远小于5cm。现有技术为提高光纤水听器探测灵敏度，需将长达数十米的光纤干涉仪两臂分别缠绕在圆柱型增敏结构上，受缠绕层数限制，缠绕区横向尺寸普遍达到10cm甚至更高。其次，为保证灵敏度达到实用要求，作为增敏结构的空气腔常需设计为细长型以增大光纤缠绕区面积，整个结构谐振频率较低，导致水听器探头高频性能不佳，不利于光纤水听器响应频段的扩展。Unfortunately, the existing interferometric fiber optic hydrophone technology still has some common problems when facing the application of high-frequency underwater acoustic signal detection. First, in order to ensure that the sensitivity meets the requirements, the length of the two arms of the interferometer needs to be increased, which in turn leads to an increase in the width of the optical fiber winding area, and the lateral size of the hydrophone probe is too large, which is not suitable for high-frequency detection applications. Taking the detection of underwater acoustic communication signals as an example, the response frequency of the hydrophone is generally required to be at least 30 kHz, and the typical wave speed in seawater is 1500 m/s, so the wavelength of the sound wave is about 5 cm. In order to avoid the directivity of the sound pressure response of the fiber optic hydrophone probe, the size of the fiber optic hydrophone probe is generally required to be much smaller than the wavelength of the sound wave, that is, the size of the probe needs to be much smaller than 5cm. In order to improve the detection sensitivity of the fiber optic hydrophone in the prior art, it is necessary to wrap the two arms of the fiber optic interferometer with a length of several tens of meters on the cylindrical sensitizing structure. high. Secondly, in order to ensure that the sensitivity meets the practical requirements, the air cavity as a sensitization structure often needs to be designed to be slender to increase the area of the fiber winding area. The resonant frequency of the entire structure is low, resulting in poor high-frequency performance of the hydrophone probe. Conducive to the expansion of the response frequency band of the fiber optic hydrophone.

因此，如何在不降低探测灵敏度的前提下减小干涉型光纤水听器尺寸，改善其高频响应特性，同时使其兼容现有工艺方案与工作模式是目前亟需解决的技术问题。Therefore, how to reduce the size of the interferometric fiber optic hydrophone without reducing the detection sensitivity, improve its high-frequency response characteristics, and make it compatible with the existing process schemes and working modes is a technical problem that needs to be solved urgently.

发明内容SUMMARY OF THE INVENTION

本发明的目的在于解决现有技术的不足而提出一种基于折叠空气腔的小尺寸干涉型高频光纤水听器，旨在实现结构紧凑、性能优越、移植性良好的高频光纤水听器，特别适用于高频水声信号探测应用。The purpose of the present invention is to solve the deficiencies of the prior art and propose a small-size interference type high-frequency optical fiber hydrophone based on a folded air cavity, aiming to realize a high-frequency optical fiber hydrophone with compact structure, superior performance and good portability , especially suitable for high-frequency underwater acoustic signal detection applications.

本发明的目的通过以下技术方案实现：The object of the present invention is achieved through the following technical solutions:

一种基于折叠空气腔的干涉型高频光纤水听器，包括4个可嵌套安装的薄壁空心圆筒：带第一光纤缠绕区101与第一支撑结构102的第一薄壁空心圆筒1，带第二光纤缠绕区201与第二支撑结构202的第二薄壁空心圆筒2，带第三光纤缠绕区301与第三支撑结构302的第三薄壁空心圆筒3，带第四光纤缠绕区401与第四支撑结构402的第四薄壁空心圆筒4，以及光纤干涉仪5；An interferometric high-frequency fiber optic hydrophone based on a folded air cavity, comprising four thin-walled hollow cylinders that can be nested and installed: a first thin-walled hollow circle with a firstfiber winding area 101 and afirst support structure 102 Cylinder 1, second thin-walledhollow cylinder 2 with secondfiber winding area 201 andsecond support structure 202, third thin-walledhollow cylinder 3 with thirdfiber winding area 301 andthird support structure 302, with the fourth opticalfiber winding area 401 and the fourth thin-walledhollow cylinder 4 of the fourth supportingstructure 402, and theoptical fiber interferometer 5;

所述第一支撑结构102的外径与所述第二薄壁空心圆筒2内径相同，当所述第一薄壁空心圆筒1嵌套进所述第二薄壁空心圆筒2后，在第一薄壁空心圆筒光纤缠绕区101处会形成第一个密封的空气腔；The outer diameter of thefirst support structure 102 is the same as the inner diameter of the second thin-walledhollow cylinder 2. When the first thin-walled hollow cylinder 1 is nested into the second thin-walledhollow cylinder 2, A first sealed air cavity will be formed at the first thin-walled hollow cylindrical opticalfiber winding area 101;

所述第二支撑结构202的外径与所述第三薄壁空心圆筒3内径相同，所述第二支撑结构202上沿圆筒轴向开有凹槽，使得液体可通过凹槽自由流过，当所述第二薄壁空心圆筒2嵌套进所述第三薄壁空心圆筒3后，在第二光纤缠绕区201处形成一个液体可自由流通的液体腔，使得缠绕在第二光纤缠绕区201与第一光纤缠绕区101的光纤干涉仪两臂形成推挽结构，对相同的声压产生相反的形变，以提高探测灵敏度；The outer diameter of thesecond support structure 202 is the same as the inner diameter of the third thin-walledhollow cylinder 3, and thesecond support structure 202 is provided with grooves along the axis of the cylinder, so that the liquid can flow freely through the grooves However, when the second thin-walledhollow cylinder 2 is nested into the third thin-walledhollow cylinder 3, a liquid cavity is formed at the second opticalfiber winding area 201 where the liquid can circulate freely, so that the winding is wound on the first optical fiber. The two opticalfiber winding areas 201 and the two arms of the optical fiber interferometer in the first opticalfiber winding area 101 form a push-pull structure, which produces opposite deformations for the same sound pressure, so as to improve the detection sensitivity;

所述第三支撑结构302的外径与所述第四薄壁空心圆筒4内径相同，当所述第三薄壁空心圆筒3嵌套进所述第四薄壁空心圆筒4后，在第三薄壁空心圆筒光纤缠绕区301处形成第二个密封的空气腔；The outer diameter of thethird support structure 302 is the same as the inner diameter of the fourth thin-walledhollow cylinder 4. When the third thin-walledhollow cylinder 3 is nested into the fourth thin-walledhollow cylinder 4, A second sealed air cavity is formed at the third thin-walled hollow cylindrical opticalfiber winding area 301;

所述光纤干涉仪5包括光入射端口501、光出射端口502、3dB耦合器503、第一光纤干涉臂504、第二光纤干涉臂505、第一法拉第旋镜506、第二法拉第旋镜507，激光从光纤干涉仪5的光入射端口501入射，经过3dB耦合器503后分为两束激光，分别进入第一光纤干涉臂504和第二光纤干涉臂505，所述第一光纤干涉臂504和第二光纤干涉臂505按照如下所述光纤缠绕方案缠绕在第一薄壁空心圆筒1、第二薄壁空心圆筒2、第三薄壁空心圆筒3、第四薄壁空心圆筒4的光纤缠绕区上以提高传感灵敏度，第一光纤干涉臂504和第二光纤干涉臂505的尾端分别连接第一法拉第旋镜506和第二法拉第旋镜507，以保证两个光纤干涉臂中的光信号反射回原光路，反射回的光信号分别经过第一光纤干涉臂504和第二光纤干涉臂505后再次进入3dB耦合器503，从与3dB耦合器503相连的光出射端口502出射，通过监测出射光强信号，可测算2个光纤干涉臂传感到的外界声压信号；Theoptical fiber interferometer 5 includes alight entrance port 501, alight exit port 502, a3dB coupler 503, a firstfiber interference arm 504, a secondfiber interference arm 505, a first Faradayrotation mirror 506, and a second Faradayrotation mirror 507. The laser is incident from thelight incident port 501 of thefiber interferometer 5, and is divided into two laser beams after passing through the3dB coupler 503, and enters the firstfiber interference arm 504 and the secondfiber interference arm 505 respectively. The firstfiber interference arm 504 and The second opticalfiber interference arm 505 is wound on the first thin-walled hollow cylinder 1 , the second thin-walledhollow cylinder 2 , the third thin-walledhollow cylinder 3 , and the fourth thin-walledhollow cylinder 4 according to the optical fiber winding scheme as described below. In order to improve the sensing sensitivity in the optical fiber winding area, the tail ends of the first opticalfiber interference arm 504 and the second opticalfiber interference arm 505 are respectively connected to the first Faradayrotation mirror 506 and the second Faradayrotation mirror 507 to ensure that the two optical fiber interference arms The optical signal in the optical fiber is reflected back to the original optical path, and the reflected optical signal passes through the first opticalfiber interference arm 504 and the second opticalfiber interference arm 505 and then enters the3dB coupler 503 again, and exits from theoptical output port 502 connected to the3dB coupler 503 , by monitoring the outgoing light intensity signal, the external sound pressure signal sensed by the two optical fiber interference arms can be measured;

所述第一薄壁空心圆筒1、第三薄壁空心圆筒3以及第四薄壁空心圆筒4均在同一端(例如右端)的支撑结构上刻有左右螺旋槽，使得光纤可缠绕进或缠绕出光纤缠绕区；The first thin-walled hollow cylinder 1, the third thin-walledhollow cylinder 3 and the fourth thin-walledhollow cylinder 4 are all engraved with left and right helical grooves on the support structure at the same end (for example, the right end), so that the optical fiber can be wound into or out of the fiber winding area;

所述光纤缠绕方案为：第一光纤干涉臂504从第一法拉第旋镜506一端开始，沿第一薄壁空心圆筒支撑结构102刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第一光纤缠绕区101，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第一光纤缠绕区101，沿第三薄壁空心圆筒支撑结构302刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第三光纤缠绕区301，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第三光纤缠绕区301后与3dB耦合器503连接；The optical fiber winding scheme is as follows: the first opticalfiber interference arm 504 starts from one end of the first Faradaymirror 506, and along the first thin-walled hollowcylindrical support structure 102 is engraved with a left helical groove (or a right helical groove) at one end of the left and right helical grooves. Winding into the first opticalfiber winding area 101, evenly and closely arranged and wound, after reaching the designed number of layers, the first opticalfiber winding area 101 is wound along the right helical groove (or left helical groove) from the same end, and is supported along the third thin-walled hollow cylinder. Thestructure 302 is engraved with a left helical groove (or a right helical groove) at one end of the left and right helical grooves and is wound into the third opticalfiber winding area 301, and is evenly and tightly wound. After winding out the thirdfiber winding area 301, it is connected with the3dB coupler 503;

第二光纤干涉臂505从第二法拉第旋镜507一端开始，沿第二薄壁空心圆筒支撑结构202刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第二光纤缠绕区201，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第二光纤缠绕区201，沿第四薄壁空心圆筒支撑结构402刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第四光纤缠绕区401，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第四光纤缠绕区401后与3dB耦合器503连接；The second opticalfiber interference arm 505 starts from one end of the second Faradayrotator 507 and is wound into the second optical fiber winding area along the second thin-walled hollowcylindrical support structure 202 with a left helical groove (or a right helical groove) engraved at one end of the left and right helical grooves. 201, evenly and closely arranged and wound, after reaching the designed number of layers, the second opticalfiber winding area 201 is wound along the right helical groove (or left helical groove) from the same end, and the left and right helical grooves are engraved along the fourth thin-walled hollowcylindrical support structure 402 The left helical groove (or right helical groove) at one end is wound into the fourth opticalfiber winding area 401, and the winding is evenly and closely arranged. After reaching the designed number of layers, the fourth optical fiber winding area is wound along the right helical groove (or left helical groove) from the same end. After 401, connect with3dB coupler 503;

所述第一薄壁空心圆筒1、第二薄壁空心圆筒2、第三薄壁空心圆筒3以及第四薄壁空心圆筒4在完成光纤干涉仪5两光纤干涉臂光纤的缠绕后，按照半径大小依次嵌套在一起，所述光纤干涉仪5第一光纤干涉臂504传感部分的光纤被缠绕在密封空气腔内部，所述光纤干涉仪第二光纤干涉臂505传感部分的光纤被缠绕在液体可自由流通的液体腔内，组成完整的光纤水听器；The first thin-walled hollow cylinder 1, the second thin-walledhollow cylinder 2, the third thin-walledhollow cylinder 3 and the fourth thin-walledhollow cylinder 4 are completing the winding of the two optical fibers of theoptical fiber interferometer 5. Then, nested together according to the size of the radius, the optical fiber of the sensing part of the first opticalfiber interference arm 504 of theoptical fiber interferometer 5 is wound inside the sealed air cavity, and the sensing part of the second opticalfiber interference arm 505 of theoptical fiber interferometer 5 The optical fiber is wound in a liquid cavity where the liquid can flow freely to form a complete optical fiber hydrophone;

优选的，所述光纤干涉臂缠绕的设计层数为4，如果需提高传感灵敏度，可进一步增加设计层数；Preferably, the design number of layers for winding the optical fiber interference arm is 4. If the sensing sensitivity needs to be improved, the design number of layers can be further increased;

优选的，所述可嵌套的薄壁空心圆筒数量不少于4个，当需要进一步提高水听器灵敏度时，可增加嵌套的薄壁空心圆筒数量。Preferably, the number of thin-walled hollow cylinders that can be nested is not less than 4. When the sensitivity of the hydrophone needs to be further improved, the number of nested thin-walled hollow cylinders can be increased.

优选的，所述第二薄壁空心圆筒结构202上沿圆筒轴向开凹槽的个数为6个。Preferably, the number of grooves on the second thin-walled hollowcylindrical structure 202 along the cylindrical axis is six.

本发明提供的一种干涉型高频光纤水听器，与现有技术相比，具有以下有益技术效果：首先，通过将传统水听器探头中细长型的空气腔创新性设计为折叠式多层空气腔结构，在不减小光纤缠绕面积，降低光纤干涉仪两臂长度的前提下，极大减小了光纤水听器横向尺寸，可提高水听器高频应用性能；其次，通过多层嵌套、折叠式空气腔的结构设计，实现了更小的半径和横向尺寸，可提高机械结构谐振频率，进而优化水听器频率响应特性；最后，结构紧凑、设计灵活、可移植性好，可兼容现有工艺方案和工作模式，方便移植到各类应用中。Compared with the prior art, the interference type high-frequency optical fiber hydrophone provided by the present invention has the following beneficial technical effects: firstly, by innovatively designing the slender air cavity in the traditional hydrophone probe into a foldable type The multi-layer air cavity structure greatly reduces the lateral size of the fiber optic hydrophone without reducing the fiber winding area and the length of the two arms of the fiber optic interferometer, which can improve the high-frequency application performance of the hydrophone; The structure design of multi-layer nested and folded air cavity achieves a smaller radius and lateral size, which can increase the resonance frequency of the mechanical structure, thereby optimizing the frequency response characteristics of the hydrophone; finally, the structure is compact, flexible in design, and portable. Yes, it is compatible with existing process schemes and working modes, and it is easy to transplant into various applications.

附图说明Description of drawings

利用附图对本发明作进一步说明，但附图中的实施例不构成对本发明的任何限制，对于本领域的普通技术人员，在不付出创造性劳动的前提下，还可以根据以下附图获得其它的附图。在附图中：The present invention will be further described by using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, under the premise of no creative work, other Attached. In the attached image:

图1是本发明所述一种干涉型高频光纤水听器的装配结构示意图；Fig. 1 is the assembly structure schematic diagram of a kind of interference type high frequency optical fiber hydrophone according to the present invention;

图2是本发明所述一种干涉型高频光纤水听器装配完成后的结构示意图；2 is a schematic structural diagram of an interference type high-frequency optical fiber hydrophone according to the present invention after assembly;

图3是本发明所述第一薄壁空心圆筒1三维结构示意图；3 is a schematic diagram of the three-dimensional structure of the first thin-walled hollow cylinder 1 according to the present invention;

图4是本发明所述第一薄壁空心圆筒1缠绕完光纤后的三维结构示意图；4 is a schematic diagram of the three-dimensional structure of the first thin-walled hollow cylinder 1 according to the present invention after the optical fiber is wound;

图5是本发明所述第二薄壁空心圆筒2三维结构示意图；5 is a schematic diagram of the three-dimensional structure of the second thin-walledhollow cylinder 2 according to the present invention;

图6是本发明所述第二薄壁空心圆筒2缠绕完光纤后的三维结构示意图；Fig. 6 is the three-dimensional structure schematic diagram of the second thin-walledhollow cylinder 2 of the present invention after winding the optical fiber;

图7是本发明所述第三薄壁空心圆筒3三维结构示意图；7 is a schematic diagram of the three-dimensional structure of the third thin-walledhollow cylinder 3 according to the present invention;

图8是本发明所述第三薄壁空心圆筒3缠绕完光纤后的三维结构示意图；8 is a three-dimensional schematic diagram of the third thin-walledhollow cylinder 3 of the present invention after the optical fiber is wound;

图9是本发明所述第四薄壁空心圆筒4三维结构示意图；9 is a schematic diagram of the three-dimensional structure of the fourth thin-walledhollow cylinder 4 according to the present invention;

图10是本发明所述第四薄壁空心圆筒4缠绕完光纤后的三维结构示意图；10 is a schematic diagram of the three-dimensional structure of the fourth thin-walledhollow cylinder 4 of the present invention after the optical fiber is wound;

图11是本发明所述光纤干涉仪5结构示意图；11 is a schematic structural diagram of theoptical fiber interferometer 5 according to the present invention;

图12是本发明所述一种干涉型高频光纤水听器实例幅频响应图。FIG. 12 is an example amplitude-frequency response diagram of an interferometric high-frequency fiber optic hydrophone according to the present invention.

附图标记说明：Description of reference numbers:

1：第一薄壁圆筒；2：第二薄壁圆筒；3：第三薄壁圆筒；4：第四薄壁圆筒；5：光纤干涉仪；1: The first thin-walled cylinder; 2: The second thin-walled cylinder; 3: The third thin-walled cylinder; 4: The fourth thin-walled cylinder; 5: Optical fiber interferometer;

101：第一光纤缠绕区；102：第一支撑结构1；103：第一左右螺旋槽；201：第二光纤缠绕区；202：第二支撑结构；203：凹槽；301：第三光纤缠绕区；302：第三支撑结构1；303：第三左右螺旋槽；401：第四光纤缠绕区；402：第四支撑结构1；403：第四左右螺旋槽；501：光入射端口；502：光出射端口；503：3dB耦合器；504：第一光纤干涉臂；505：第一光纤干涉臂；506：第一法拉第旋镜；507：第二法拉第旋镜。101: First fiber winding area; 102: First support structure 1; 103: First left and right helical grooves; 201: Second fiber winding area; 202: Second support structure; 203: Groove; 301: Third fiber winding area; 302: third support structure 1; 303: third left and right helical grooves; 401: fourth fiber winding area; 402: fourth support structure 1; 403: fourth left and right helical grooves; 501: light entrance port; 502: 503: 3dB coupler; 504: first optical fiber interference arm; 505: first optical fiber interference arm; 506: first Faraday rotation mirror; 507: second Faraday rotation mirror.

具体实施方式Detailed ways

为了使本领域的技术人员更好地理解本发明的技术方案，下面结合附图和具体实施例对本发明作进一步详细的描述，需要说明的是，在不冲突的情况下，本申请的实施例及实施例中的特征可以相互组合。In order to make those skilled in the art better understand the technical solutions of the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. and features of the embodiments may be combined with each other.

图1是本发明一种干涉型高频光纤水听器一实施例的结构示意图，图2是本发明所述一种干涉型高频光纤水听器装配完成后的结构示意图，图3是本发明所述第一薄壁空心圆筒1三维结构示意图，图4是本发明所述第一薄壁空心圆筒1缠绕完光纤后的三维结构示意图，图5是本发明所述第二薄壁空心圆筒2三维结构示意图，图6是本发明所述第二薄壁空心圆筒2缠绕完光纤后的三维结构示意图，图7是本发明所述第三薄壁空心圆筒3三维结构示意图，图8是本发明所述第三薄壁空心圆筒3缠绕完光纤后的三维结构示意图，图9是本发明所述第四薄壁空心圆筒4三维结构示意图，图10是本发明所述第四薄壁空心圆筒4缠绕完光纤后的三维结构示意图，图11是本发明所述光纤干涉仪5结构示意图。1 is a schematic structural diagram of an embodiment of an interference type high-frequency optical fiber hydrophone according to the present invention, FIG. 2 is a schematic structural diagram of an interference type high-frequency optical fiber hydrophone according to the present invention after assembly, and FIG. 3 is a schematic diagram of the present invention. Schematic diagram of the three-dimensional structure of the first thin-walled hollow cylinder 1 according to the present invention, FIG. 4 is a schematic diagram of the three-dimensional structure of the first thin-walled hollow cylinder 1 according to the present invention after winding the optical fiber, and FIG. 5 is the second thin-walled hollow cylinder 1 of the present invention. A schematic diagram of the three-dimensional structure of thehollow cylinder 2, FIG. 6 is a schematic diagram of the three-dimensional structure of the second thin-walledhollow cylinder 2 according to the present invention after the optical fiber is wound, and FIG. 7 is a schematic diagram of the three-dimensional structure of the third thin-walledhollow cylinder 3 of the present invention. , FIG. 8 is a three-dimensional structural schematic diagram of the third thin-walledhollow cylinder 3 of the present invention after winding the optical fiber, FIG. 9 is a three-dimensional structural schematic diagram of the fourth thin-walledhollow cylinder 4 of the present invention, and FIG. 10 is a schematic diagram of the three-dimensional structure of the present invention. Fig. 11 is a schematic structural diagram of theoptical fiber interferometer 5 according to the present invention.

本发明所述一种基于折叠空气腔的干涉型高频光纤水听器，包括4个可嵌套安装的薄壁空心圆筒：带第一光纤缠绕区101与第一支撑结构102的第一薄壁空心圆筒1，带第二光纤缠绕区201与第二支撑结构202的第二薄壁空心圆筒2，带第三光纤缠绕区301与第三支撑结构302的第三薄壁空心圆筒3，以及带第四光纤缠绕区401与第四支撑结构402的第四薄壁空心圆筒4，以及光纤干涉仪5；The interference type high-frequency fiber optic hydrophone based on a folded air cavity according to the present invention includes four thin-walled hollow cylinders that can be nested and installed: a firstfiber winding area 101 and afirst support structure 102. Thin-walled hollow cylinder 1, second thin-walledhollow cylinder 2 with second opticalfiber winding area 201 andsecond support structure 202, third thin-walled hollow circle with third opticalfiber winding area 301 andthird support structure 302Cylinder 3, and a fourth thin-walledhollow cylinder 4 with a fourth opticalfiber winding area 401 and a fourth supportingstructure 402, and anoptical fiber interferometer 5;

所述第一支撑结构102的外径与所述第二薄壁空心圆筒2内径相同，当所述第一薄壁空心圆筒1嵌套进所述第二薄壁空心圆筒2后，在第一薄壁空心圆筒光纤缠绕区101处会形成第一个密封的空气腔；The outer diameter of thefirst support structure 102 is the same as the inner diameter of the second thin-walledhollow cylinder 2. When the first thin-walled hollow cylinder 1 is nested into the second thin-walledhollow cylinder 2, A first sealed air cavity will be formed at the first thin-walled hollow cylindrical opticalfiber winding area 101;

所述第二支撑结构202的外径与所述第三薄壁空心圆筒3内径相同，所述第二支撑结构202上沿圆筒轴向开有6个凹槽202，使得液体可通过凹槽自由流过，当所述第二薄壁空心圆筒2嵌套进所述第三薄壁空心圆筒3后，在第二光纤缠绕区201处形成一个液体可自由流通的液体腔，使得缠绕在第二光纤缠绕区201与第一光纤缠绕区101的光纤干涉仪两臂形成推挽结构，对相同的声压产生相反的形变，以提高探测灵敏度；The outer diameter of thesecond support structure 202 is the same as the inner diameter of the third thin-walledhollow cylinder 3, and sixgrooves 202 are formed on thesecond support structure 202 along the cylinder axis, so that the liquid can pass through the grooves. The groove flows freely, and when the second thin-walledhollow cylinder 2 is nested into the third thin-walledhollow cylinder 3, a liquid cavity in which the liquid can freely circulate is formed at the second opticalfiber winding area 201, so that The two arms of the optical fiber interferometer wound in the second opticalfiber winding area 201 and the first opticalfiber winding area 101 form a push-pull structure, which produces opposite deformations for the same sound pressure, so as to improve the detection sensitivity;

所述第三支撑结构302的外径与所述第四薄壁空心圆筒4内径相同，当所述第三薄壁空心圆筒3嵌套进所述第四薄壁空心圆筒4后，在第三薄壁空心圆筒光纤缠绕区301处形成第二个密封的空气腔；The outer diameter of thethird support structure 302 is the same as the inner diameter of the fourth thin-walledhollow cylinder 4. When the third thin-walledhollow cylinder 3 is nested into the fourth thin-walledhollow cylinder 4, A second sealed air cavity is formed at the third thin-walled hollow cylindrical opticalfiber winding area 301;

所述光纤干涉仪5包括光入射端口501、光出射端口502、3dB耦合器503、第一光纤干涉臂504、第二光纤干涉臂505、第一法拉第旋镜506、第二法拉第旋镜507，激光从光纤干涉仪5的光入射端口501入射，经过3dB耦合器503后分为两束激光，分别进入第一光纤干涉臂504和第二光纤干涉臂505，所述第一光纤干涉臂504和第二光纤干涉臂505按照如下所述光纤缠绕方案缠绕在第一薄壁空心圆筒1、第二薄壁空心圆筒2、第三薄壁空心圆筒3、第四薄壁空心圆筒4的光纤缠绕区上以提高传感灵敏度，第一光纤干涉臂504和第二光纤干涉臂505的尾端分别连接第一法拉第旋镜506和第二法拉第旋镜507，以保证两个光纤干涉臂中的光信号反射回原光路，反射回的光信号分别经过第一光纤干涉臂504和第二光纤干涉臂505后再次进入3dB耦合器503后，从与3dB耦合器503相连的光出射端口502出射，通过监测出射光强信号，可测算2个光纤干涉臂传感到的外界声压信号；Theoptical fiber interferometer 5 includes alight entrance port 501, alight exit port 502, a3dB coupler 503, a firstfiber interference arm 504, a secondfiber interference arm 505, a firstFaraday rotation mirror 506, and a secondFaraday rotation mirror 507. The laser is incident from thelight incident port 501 of thefiber interferometer 5, and is divided into two laser beams after passing through the3dB coupler 503, and enters the firstfiber interference arm 504 and the secondfiber interference arm 505 respectively. The firstfiber interference arm 504 and The second opticalfiber interference arm 505 is wound on the first thin-walled hollow cylinder 1 , the second thin-walledhollow cylinder 2 , the third thin-walledhollow cylinder 3 , and the fourth thin-walledhollow cylinder 4 according to the optical fiber winding scheme as described below. In order to improve the sensing sensitivity in the optical fiber winding area, the tail ends of the first opticalfiber interference arm 504 and the second opticalfiber interference arm 505 are respectively connected to the firstFaraday rotation mirror 506 and the secondFaraday rotation mirror 507 to ensure that the two optical fiber interference arms The optical signal in the optical fiber is reflected back to the original optical path, and the reflected optical signal passes through the first opticalfiber interference arm 504 and the second opticalfiber interference arm 505 and then enters the3dB coupler 503 again. Outgoing, by monitoring the outgoing light intensity signal, the external sound pressure signal sensed by the two optical fiber interference arms can be measured;

所述第一薄壁空心圆筒1、第三薄壁空心圆筒3以及第四薄壁空心圆筒4均在同一端(例如右端)的支撑结构上分别刻有第一左右螺旋槽103、第三左右螺旋槽303和第四左右螺旋槽403，使得光纤可缠绕进或缠绕出光纤缠绕区；The first thin-walled hollow cylinder 1, the third thin-walledhollow cylinder 3 and the fourth thin-walledhollow cylinder 4 are respectively engraved with first left and righthelical grooves 103, The third left and righthelical grooves 303 and the fourth left and righthelical grooves 403 enable the optical fiber to be wound into or out of the optical fiber winding area;

所述光纤缠绕方案为：薄壁空心圆筒第一光纤干涉臂504从第一法拉第旋镜506一端开始，沿第一薄壁空心圆筒支撑结构102刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第一光纤缠绕区101，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第一光纤缠绕区101后，沿第三薄壁空心圆筒支撑结构302刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第三光纤缠绕区301，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第三光纤缠绕区301后与3dB耦合器503连接；The optical fiber winding scheme is as follows: the first opticalfiber interference arm 504 of the thin-walled hollow cylinder starts from one end of thefirst Faraday mirror 506, and along the first thin-walled hollowcylinder support structure 102 is engraved with a left helical groove ( or right helical groove) is wound into the first opticalfiber winding area 101, evenly and closely arranged and wound, and after reaching the designed number of layers, the first opticalfiber winding area 101 is wound along the right helical groove (or left helical groove) from the same end, and then the first opticalfiber winding area 101 is wound along the third The thin-walled hollowcylindrical support structure 302 is engraved with a left helical groove (or a right helical groove) at one end of the left and right helical grooves, and is wound into the third opticalfiber winding area 301, and is evenly and tightly wound. (or left helical groove) is wound out of the thirdfiber winding area 301 and connected to the3dB coupler 503;

薄壁空心圆筒第二光纤干涉臂505从第二法拉第旋镜507一端开始，沿第二薄壁空心圆筒支撑结构202刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第二光纤缠绕区201，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第二光纤缠绕区201后，沿第四薄壁空心圆筒支撑结构402刻有左右螺旋槽一端的左螺旋槽(或右螺旋槽)缠绕进第四光纤缠绕区401，均匀紧密排列缠绕，达到设计层数后从同一端沿右螺旋槽(或左螺旋槽)缠绕出第四光纤缠绕区401后与3dB耦合器503连接；The thin-walled hollow cylinder second opticalfiber interference arm 505 starts from one end of thesecond Faraday mirror 507, and is wound into the left helical groove (or right helical groove) engraved with one end of the left and right helical grooves along the second thin-walled hollowcylinder support structure 202. The second opticalfiber winding area 201 is evenly and closely arranged and wound. After reaching the designed number of layers, the second opticalfiber winding area 201 is wound along the right helical groove (or left helical groove) from the same end, followed by the fourth thin-walled hollow cylindrical support structure. 402 The left helical groove (or right helical groove) engraved at one end of the left and right helical grooves is wound into the fourth opticalfiber winding area 401, and the winding is evenly and closely arranged. After reaching the designed number of layers, the left helical groove (or the right helical groove) is wound from the same end along the right helical groove (or left helical groove). After exiting the fourthfiber winding area 401, it is connected with a3dB coupler 503;

所述第一薄壁空心圆筒1、第二薄壁空心圆筒2、第三薄壁空心圆筒3以及第四薄壁空心圆筒4在完成光纤干涉仪5两光纤干涉臂光纤的缠绕后，按照半径大小依次嵌套在一起，所述光纤干涉仪5第一光纤干涉臂504传感部分的光纤被缠绕在密封空气腔内部，所述光纤干涉仪第二光纤干涉臂505传感部分的光纤被缠绕在液体可自由流通的液体腔内，组成完整的光纤水听器；The first thin-walled hollow cylinder 1, the second thin-walledhollow cylinder 2, the third thin-walledhollow cylinder 3 and the fourth thin-walledhollow cylinder 4 are completing the winding of the two optical fibers of theoptical fiber interferometer 5. Then, nested together according to the size of the radius, the optical fiber of the sensing part of the first opticalfiber interference arm 504 of theoptical fiber interferometer 5 is wound inside the sealed air cavity, and the sensing part of the second opticalfiber interference arm 505 of theoptical fiber interferometer 5 The optical fiber is wound in a liquid cavity where the liquid can flow freely to form a complete optical fiber hydrophone;

图12是本发明所述一种干涉型高频光纤水听器实例幅频响应图。FIG. 12 is an example amplitude-frequency response diagram of an interferometric high-frequency fiber optic hydrophone according to the present invention.

以上所述的具体实施例，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施例而已，并不用于限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. The utility model provides an interference type high frequency optic fibre hydrophone based on folding air chamber which characterized in that: the device comprises 4 thin-wall hollow cylinders which can be embedded and installed: a first thin-walled hollow cylinder (1) with a first fiber winding area (101) and a first support structure (102), a second thin-walled hollow cylinder (2) with a second fiber winding area (201) and a second support structure (202), a third thin-walled hollow cylinder (3) with a third fiber winding area (301) and a third support structure (302), a fourth thin-walled hollow cylinder (4) with a fourth fiber winding area (401) and a fourth support structure (402), and a fiber interferometer (5);

the outer diameter of the first supporting structure (102) is the same as the inner diameter of the second thin-wall hollow cylinder (2), and when the first thin-wall hollow cylinder (1) is nested in the second thin-wall hollow cylinder (2), a first sealed air cavity is formed at the optical fiber winding area (101) of the first thin-wall hollow cylinder;

the outer diameter of the second supporting structure (202) is the same as the inner diameter of the third thin-wall hollow cylinder (3), a groove is formed in the second supporting structure (202) along the axial direction of the cylinder, so that liquid can freely flow through the groove, and after the second thin-wall hollow cylinder (2) is nested in the third thin-wall hollow cylinder (3), a liquid cavity in which liquid can freely flow is formed in the second optical fiber winding area (201), so that two arms of an optical fiber interferometer wound on the second optical fiber winding area (201) and the first optical fiber winding area (101) form a push-pull structure, and opposite deformation is generated on the same sound pressure, so that the detection sensitivity is improved;

the outer diameter of the third supporting structure (302) is the same as the inner diameter of the fourth thin-wall hollow cylinder (4), and when the third thin-wall hollow cylinder (3) is nested in the fourth thin-wall hollow cylinder (4), a second sealed air cavity is formed at the optical fiber winding area (301) of the third thin-wall hollow cylinder;

the optical fiber interferometer (5) comprises a light incidence port (501), a light emergent port (502), a 3dB coupler (503), a first optical fiber interference arm (504), a second optical fiber interference arm (505), a first Faraday rotator mirror (506) and a second Faraday rotator mirror (507), laser is incident from the light incidence port (501) of the optical fiber interferometer (5), is divided into two beams of laser after passing through the 3dB coupler (503), and respectively enters the first optical fiber interference arm (504) and the second optical fiber interference arm (505), the first optical fiber interference arm (504) and the second optical fiber interference arm (505) are wound on optical fiber winding regions of the first thin-wall hollow cylinder (1), the second thin-wall hollow cylinder (2), the third thin-wall hollow cylinder (3) and the fourth thin-wall hollow cylinder (4) according to the optical fiber winding scheme to improve the sensing sensitivity, and tail ends of the first optical fiber interference arm (504) and the second optical fiber interference arm (505) are respectively connected with the first Faraday rotator mirror (506) The second Faraday rotator (507) is used for ensuring that optical signals in the two optical fiber interference arms are reflected back to an original optical path, the reflected optical signals respectively pass through the first optical fiber interference arm (504) and the second optical fiber interference arm (505) and then enter the 3dB coupler (503), the optical signals are emitted from an optical emitting port (502) connected with the 3dB coupler (503), and external sound pressure signals sensed by the 2 optical fiber interference arms can be measured by monitoring emitted light intensity signals;

the first thin-wall hollow cylinder (1), the third thin-wall hollow cylinder (3) and the fourth thin-wall hollow cylinder (4) are all provided with a left spiral groove and a right spiral groove on a supporting structure at the same end, so that optical fibers can be wound into or out of an optical fiber winding area;

the optical fiber winding scheme is as follows: the first optical fiber interference arm (504) winds a left spiral groove, which is engraved with a left spiral groove and a right spiral groove at one end of the left spiral groove and the right spiral groove, into a first optical fiber winding area (101) from one end of a first Faraday rotator (506) along a first thin-wall hollow cylinder supporting structure (102), is uniformly and tightly arranged and wound, winds the first optical fiber winding area (101) from the same end along the right spiral groove after reaching a designed number of layers, winds the left spiral groove, which is engraved with the left spiral groove and the right spiral groove at one end along a third thin-wall hollow cylinder supporting structure (302), winds the left spiral groove and the right spiral groove into a third optical fiber winding area (301), is uniformly and tightly arranged and wound, winds the third optical fiber winding area (301) from the same end along the right spiral groove after reaching the designed number of;

the second optical fiber interference arm (505) winds a left spiral groove, which is engraved with one end of a left spiral groove and a right spiral groove, into the second optical fiber winding area (201) from one end of the second Faraday rotator (507) along the second thin-wall hollow cylinder supporting structure (202), is uniformly and tightly arranged and wound, winds the second optical fiber winding area (201) from the same end along the right spiral groove after reaching the designed number of layers, winds the left spiral groove, which is engraved with one end of the left spiral groove and the right spiral groove along the fourth thin-wall hollow cylinder supporting structure (402), into the fourth optical fiber winding area (401), is uniformly and tightly arranged and wound, winds the fourth optical fiber winding area (401) from the same end along the right spiral groove after reaching the designed number of layers, and is connected with the 3dB coupler (503);

the optical fiber hydrophone comprises a first thin-wall hollow cylinder (1), a second thin-wall hollow cylinder (2), a third thin-wall hollow cylinder (3) and a fourth thin-wall hollow cylinder (4), wherein after the optical fibers of two optical fiber interference arms of an optical fiber interferometer (5) are wound, the optical fibers are sequentially nested together according to the radius, the optical fibers of a sensing part of a first optical fiber interference arm (504) of the optical fiber interferometer (5) are wound inside a sealed air cavity, and the optical fibers of a sensing part of a second optical fiber interference arm (505) of the optical fiber interferometer are wound inside a liquid cavity in which liquid can freely circulate, so that the complete optical fiber hydrophone is formed.

2. A folded air cavity based interferometric high frequency fiber optic hydrophone according to claim 1, wherein: the number of design layers for winding the optical fiber interference arm is 4.

3. A folded air cavity based interferometric high frequency fiber optic hydrophone according to claim 2, wherein: the number of design layers for winding the optical fiber interference arm can be further increased according to the requirement of improving the sensing sensitivity.

4. A folded air cavity based interferometric high frequency fiber optic hydrophone according to claim 1, wherein: the nestable thin-wall hollow cylinders are not less than 4 in number.

5. A folded air cavity based interferometric high frequency fiber optic hydrophone according to claim 1, wherein: the number of the grooves formed in the second thin-wall hollow cylindrical structure (202) along the axial direction of the cylinder is 6.

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