Double-interferometer push-pull and common-mode noise differential suppression optical fiber hydrophone

Abstract

The utility model is suitable for the technical field of optical fiber sensing, and relates to a double-interferometer push-pull and common-mode noise differential suppression optical fiber hydrophone, which comprises a first thin-wall cylinder, a second thin-wall cylinder, a first optical fiber interferometer and a second optical fiber interferometer, the first thin-wall cylinder is embedded in the second thin-wall cylinder, a first optical fiber winding area and a second optical fiber winding area are arranged on the first thin-wall cylinder, and a third optical fiber winding area and a fourth optical fiber winding area are arranged on the second thin-wall cylinder; the first optical fiber interferometer comprises a first short-arm sensing optical fiber, a first long-arm sensing optical fiber, a first Faraday rotating mirror and a second Faraday rotating mirror, and the second optical fiber interferometer comprises a second short-arm sensing optical fiber, a second long-arm sensing optical fiber, a third Faraday rotating mirror and a fourth Faraday rotating mirror. According to the utility model, the dual-push-pull structure is formed by the dual-fiber interferometer, so that temperature drift noise and optical scattering noise caused by the ultra-long sensing fiber are reduced, and common-mode noise formed by light source vibration, transmission optical cable jitter and the like is suppressed.

Description

Technical Field

[0001] This utility model belongs to the field of fiber optic sensing technology, and in particular relates to a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression. Background Technology

[0002] Fiber optic hydrophones are underwater acoustic sensors based on fiber optic and optoelectronic technologies. They have the characteristics of being resistant to electromagnetic interference, having low signal crosstalk, and being easy to deploy in large-scale arrays. They have attracted widespread attention both at home and abroad and have become an important new technological approach for underwater target detection and underwater acoustic survey equipment.

[0003] Based on their detection principles, fiber optic hydrophones can be categorized into wavelength-type, intensity-type, and interferometric types. Among these, interferometric fiber optic hydrophones, with their high sensitivity, ease of arraying, and user-friendly manufacturing processes, have become the mainstream technology in the industry. Traditional interferometric fiber optic hydrophones are all based on a single-fiber interferometer structure. Given a fixed hydrophone skeleton material and structural parameters to ensure hydrostatic pressure resistance, the acoustic pressure phase shift sensitivity is generally improved by extending the length of the sensing fiber in the interferometer. However, as the sensing fiber length increases, the increase in fiber length leads to increased temperature drift noise and optical scattering noise, raising the system's background phase noise and resulting in a higher equivalent noise pressure. Furthermore, transmission cable jitter and low-frequency noise from the light source are difficult to eliminate in fiber optic hydrophones with a single-fiber interferometer structure. Although existing technologies propose using acoustic pressure-insensitive fiber optic hydrophones with the same parameters for adaptive elimination of transmission cable jitter and low-frequency noise, their suppression capability is limited because they cannot achieve absolute point-to-point detection with the sensing hydrophone. Patent CN202020809189.X discloses an interferometric fiber optic vector hydrophone with a reference interferometer, comprising a mass block, an elastic cylinder, a fiber optic interferometer, and a housing for placing the mass block, elastic cylinder, and fiber optic interferometer. The fiber optic hydrophone in this patent also employs a single-fiber interferometer structure, resulting in poor suppression performance and exhibiting the same drawbacks as existing technologies.

[0004] Therefore, it is imperative to address the challenges of suppressing jitter in ultra-long sensing optical fibers and transmission cables, as well as low-frequency noise from light sources, in the sensitization design of traditional fiber optic hydrophones. Utility Model Content

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression, in order to solve the problems of using ultra-long sensing fibers and the difficulty in suppressing jitter of transmission cables and low-frequency noise from light sources in the sensitivity enhancement design of traditional fiber optic hydrophones.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This invention provides a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression, comprising:

[0008] The system comprises a first thin-walled cylinder, a second thin-walled cylinder, a first fiber optic interferometer, and a second fiber optic interferometer. The first thin-walled cylinder is embedded within the second thin-walled cylinder, forming an air cavity. The first thin-walled cylinder has a first fiber optic winding area and a second fiber optic winding area, while the second thin-walled cylinder has a third fiber optic winding area and a fourth fiber optic winding area. The first fiber optic interferometer includes a first short-arm sensing fiber, a first long-arm sensing fiber, a first Faraday rotator, and a second Faraday rotator. The second fiber optic interferometer includes a second short-arm sensing fiber, a second long-arm sensing fiber, a third Faraday rotator, and a fourth Faraday rotator. The first short-arm sensing fiber is connected to the first Faraday rotator. The first long-arm sensing fiber is connected to the second Faraday rotator, the second short-arm sensing fiber is connected to the third Faraday rotator, and the second long-arm sensing fiber is connected to the fourth Faraday rotator. The first short-arm sensing fiber and the second long-arm sensing fiber are wound side-by-side on the first fiber winding area and the second fiber winding area. The first Faraday rotator and the fourth Faraday rotator are fixedly connected to the inner wall of the first thin-walled cylinder. The first long-arm sensing fiber and the second short-arm sensing fiber are wound side-by-side on the third fiber winding area and the fourth fiber winding area. The second Faraday rotator and the third Faraday rotator are fixedly connected to the inner wall of the first thin-walled cylinder.

[0009] Furthermore, the first thin-walled cylinder is also provided with a first supporting rib, a second supporting rib and a third supporting rib. The first supporting rib and the third supporting rib are respectively located at both ends of the first thin-walled cylinder, and the second supporting rib is located at the middle position of the first thin-walled cylinder.

[0010] Furthermore, the second thin-walled cylinder is also provided with a fourth support rib, a fifth support rib and a sixth support rib. The fourth support rib and the sixth support rib are respectively located at both ends of the second thin-walled cylinder, and the fifth support rib is located at the middle position of the second thin-walled cylinder.

[0011] Furthermore, the outer diameters of the first, second, and third supporting ribs are the same, and they are also the same as the inner diameter of the second thin-walled cylinder.

[0012] Furthermore, the second, third, fifth, and sixth support ribs are each provided with left and right spiral grooves of the same pitch and depth, which are used to cross the support ribs and enter the adjacent optical fiber winding area during optical fiber winding.

[0013] Furthermore, the first fiber interferometer also includes a first fiber coupler, with the first short-arm sensing fiber and the first long-arm sensing fiber respectively connected to the first fiber coupler.

[0014] Furthermore, the first fiber optic interferometer also includes a first optical input pigtail and a first optical output pigtail, which are respectively connected to the first fiber optic coupler.

[0015] Furthermore, the second fiber interferometer also includes a second fiber coupler, with the second short-arm sensing fiber and the second long-arm sensing fiber respectively connected to the second fiber coupler.

[0016] Furthermore, the second fiber interferometer also includes a second optical input pigtail and a second optical output pigtail, which are respectively connected to the second fiber coupler.

[0017] Furthermore, the optical fiber is wound in two layers.

[0018] Compared with the prior art, the fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided by this utility model has at least the following advantages:

[0019] Traditional fiber optic hydrophone sensitivity enhancement designs often use ultra-long sensing fibers, and it is difficult to suppress transmission cable jitter and low-frequency noise from the light source. This invention features a simple structure and convenient operation. It employs a dual-fiber interferometer as the optical sensing element, forming a dual push-pull and differential detection structure. Under the influence of an acoustic signal, one of the sensing fibers in a single fiber interferometer extends while the other shortens, forming a single push-pull structure. The difference between the two fibers is twice the deformation of the single-arm sensing fiber, thereby increasing the relative deformation between the two sensing arms and enhancing the sensitivity of the fiber optic hydrophone. In contrast, the two fiber interferometers in this invention have opposite fiber deformation directions and equal magnitudes, forming a dual push-pull structure. After differential calculation, the signal amplitude becomes twice that of a single fiber interferometer. Compared to traditional high-sensitivity single-fiber interferometer hydrophones using ultra-long sensing fibers, the length of each fiber interferometer sensing fiber is reduced to half that of a traditional single-fiber interferometer hydrophone, while maintaining the same sound pressure sensitivity. This reduces the temperature drift and optical scattering noise caused by ultra-long sensing fibers in a single fiber interferometer hydrophone. Furthermore, the push-pull differential detection method of the dual interferometer structure suppresses transmission cable jitter and low-frequency noise from the light source, thus reducing the background phase noise. Attached Figure Description

[0020] To more clearly illustrate the solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 A schematic diagram of an assembly of a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0022] Figure 2 A schematic diagram of the first thin-walled cylindrical structure of a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0023] Figure 3 A schematic diagram of the second thin-walled cylindrical structure of a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0024] Figure 4 A schematic diagram of the completed assembly of a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression, provided for an embodiment of this utility model;

[0025] Figure 5 A schematic diagram of the first fiber optic interferometer structure for a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0026] Figure 6 A schematic diagram of the second fiber optic interferometer structure for a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0027] Figure 7 A common-mode noise differential suppression effect diagram of a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0028] Figure 8 A signal differential output diagram of a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression provided for an embodiment of this utility model;

[0029] Reference numerals: 10-First thin-walled cylinder; 101-First fiber winding area; 102-Second fiber winding area; 103-First supporting rib; 104-Second supporting rib; 105-Third supporting rib; 20-Second thin-walled cylinder; 201-Third fiber winding area; 202-Fourth fiber winding area; 203-Fourth supporting rib; 204-Fifth supporting rib; 205-Sixth supporting rib; 30-First fiber interferometer; 301-First fiber input pigtail; 302- 303 - First fiber optic output pigtail; 304 - First short-arm sensing fiber; 305 - First long-arm sensing fiber; 306 - First Faraday rotator; 307 - Second Faraday rotator; 40 - Second fiber optic interferometer; 401 - Second optical input pigtail; 402 - Second optical output pigtail; 403 - Second fiber optic coupler; 404 - Second short-arm sensing fiber; 405 - Second long-arm sensing fiber; 406 - Third Faraday rotator; 407 - Fourth Faraday rotator. Detailed Implementation

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as “length,” “width,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” indicate orientations or positions based on the orientations or positions shown in the accompanying drawings and are merely for ease of description and should not be construed as limiting the invention.

[0031] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this utility model are intended to cover non-exclusive inclusion; the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish different objects, not to describe a particular order. In the specification, claims, and accompanying drawings of this utility model, when an element is referred to as "fixed to," "mounted to," "set on," or "connected to" another element, it can be directly or indirectly located on that other element. For example, when an element is referred to as "connected to" another element, it can be directly or indirectly connected to that other element.

[0032] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] This invention provides a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression, applied in the detection of underwater sound pressure signals. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression includes:

[0034] The system comprises a first thin-walled cylinder, a second thin-walled cylinder, a first fiber optic interferometer, and a second fiber optic interferometer. The first thin-walled cylinder is embedded within the second thin-walled cylinder, forming an air cavity. The first thin-walled cylinder has a first fiber optic winding area and a second fiber optic winding area, while the second thin-walled cylinder has a third fiber optic winding area and a fourth fiber optic winding area. The first fiber optic interferometer includes a first short-arm sensing fiber, a first long-arm sensing fiber, a first Faraday rotator, and a second Faraday rotator. The second fiber optic interferometer includes a second short-arm sensing fiber, a second long-arm sensing fiber, a third Faraday rotator, and a fourth Faraday rotator. The first short-arm sensing fiber is connected to the first... The Faraday rotator is connected to the first long-arm sensing fiber, which is connected to the second Faraday rotator. The second short-arm sensing fiber is connected to the third Faraday rotator. The second long-arm sensing fiber is connected to the fourth Faraday rotator. The first short-arm sensing fiber and the second long-arm sensing fiber are wound side by side on the first fiber winding area and the second fiber winding area. The first Faraday rotator and the fourth Faraday rotator are fixedly connected to the inner wall of the first thin-walled cylinder. The first long-arm sensing fiber and the second short-arm sensing fiber are wound side by side on the third fiber winding area and the fourth fiber winding area. The second Faraday rotator and the third Faraday rotator are fixedly connected to the inner wall of the first thin-walled cylinder.

[0035] This invention employs a dual-fiber interferometer to form a dual push-pull structure, which effectively reduces temperature drift noise and optical scattering noise caused by ultra-long sensing fibers, and effectively suppresses common-mode noise caused by light source vibration and transmission cable jitter.

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0037] This invention provides a fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression, applied in the detection of underwater sound pressure signals, combined with... Figures 1 to 8 In this embodiment, the fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression includes:

[0038] A first thin-walled cylinder 10, a second thin-walled cylinder 20, a first fiber optic interferometer 30, and a second fiber optic interferometer 40 are provided. The first and second thin-walled cylinders 10 and 20 can be made of metal or organic polymer. The first thin-walled cylinder 10 includes a first fiber optic winding area 101, a second fiber optic winding area 102, a first supporting rib 103, a second supporting rib 104, and a third supporting rib 105. The second thin-walled cylinder 20 also includes the first fiber optic winding area 201, the second fiber optic winding area 202, the first supporting rib 203, the second supporting rib 204, and the third supporting rib 205. The outer diameters of the first supporting rib 103, the second supporting rib 104, and the third supporting rib 105 of the first thin-walled cylinder 10 are equal to and the same as the inner diameter of the second thin-walled cylinder 20. The first thin-walled cylinder 10 can be nested into the second thin-walled cylinder 20. The first support rib 103, the second support rib 104, and the third support rib 105 of a thin-walled cylinder 10 are bonded and fixed to the inner wall of the second thin-walled cylinder 20 by structural adhesive. An air cavity is formed between the first optical fiber winding area 101 of the first thin-walled cylinder 10 and the first optical fiber winding area 201 of the second thin-walled cylinder 20, and between the second optical fiber winding area 102 of the first thin-walled cylinder 10 and the second optical fiber winding area 201 of the second thin-walled cylinder 20. The second support ribs 104 and 105 of the first thin-walled cylinder 10 and the second support ribs 204 and 205 of the second thin-walled cylinder 20 are all engraved with left and right spiral grooves with the same pitch and depth. During optical fiber winding, the left and right spiral grooves can cross the support ribs to enter the adjacent optical fiber winding area. The bottom of the left and right spiral grooves should be flush with the corresponding optical fiber winding area.

[0039] Furthermore, in this embodiment, the first fiber optic interferometer 30 includes a first optical input pigtail 301, a first optical output pigtail 302, a first fiber optic coupler 303, a first short-arm sensing fiber 304, a first long-arm sensing fiber 305, a first Faraday rotator mirror 306, and a second Faraday rotator mirror 307. The first optical input pigtail 301 and the first optical output pigtail 302 are respectively connected to one end of the first fiber optic coupler 303. The first short-arm sensing fiber 304 and the first long-arm sensing fiber 305 are respectively connected to the other end of the first fiber optic coupler 303. The first short-arm sensing fiber 304 is connected to the first Faraday rotator mirror 306, and the first long-arm sensing fiber 305 is connected to the second Faraday rotator mirror 307. The second fiber optic interferometer 40... It includes a second optical input pigtail 401, a second optical output pigtail 402, a second fiber coupler 403, a second short-arm sensing fiber 404, a second long-arm sensing fiber 405, a third Faraday rotator 406, and a fourth Faraday rotator 407. The second optical input pigtail 401 and the second optical output pigtail 402 are respectively connected to one end of the second fiber coupler 403. The second short-arm sensing fiber 404 and the second long-arm sensing fiber 405 are respectively connected to the other end of the second fiber coupler 403. The second short-arm sensing fiber 404 is connected to the third Faraday rotator 406, and the second long-arm sensing fiber 405 is connected to the fourth Faraday rotator 407. The specifications of the first fiber interferometer 30 and the second fiber interferometer 40 are completely identical.

[0040] Specifically, in this embodiment, the optical fiber winding method on the first thin-walled cylinder 10 is as follows: the first short-arm sensing fiber 304 of the first optical fiber interferometer 30 and the second long-arm sensing fiber 405 of the second optical fiber interferometer 40 are wound in parallel and synchronously and tightly onto the first optical fiber winding area 101 and the second optical fiber winding area 102 of the first thin-walled cylinder 10. During winding, the winding starts from one end of the first optical fiber coupler 303 and the second optical fiber coupler 403, respectively, and enters from the left thread groove (or right thread groove) of the third support rib 105. The winding of the designed number of turns on the second optical fiber winding area 102 is completed evenly and densely, and the winding begins from the left thread groove (or right thread groove) of the second support rib 104. The fiber enters the first fiber winding area 101 through the groove and is wound closely until the designed number of turns is completed. Then, starting from the current position, the next layer is wound in the reverse direction on the first fiber winding area 101. During the winding process, the fiber enters the second fiber winding area 102 through the right thread groove (or left thread groove) of the second support rib 104. After completing the specified number of turns, the fiber exits the second fiber winding area 102 through the right thread groove (or left thread groove) of the third support rib 105. The first Faraday rotator 306 at the end of the first short-arm sensing fiber 304 and the fourth Faraday rotator 407 at the end of the second long-arm sensing fiber 405 are glued to the inner wall of the first thin-walled cylinder 10.

[0041] Specifically, in this embodiment, the optical fiber winding method on the second thin-walled cylinder 20 is as follows: the first long-arm sensing optical fiber 305 of the first optical fiber interferometer 30 and the second short-arm sensing optical fiber 404 of the second optical fiber interferometer 40 are wound in parallel and synchronously and tightly onto the first optical fiber winding area 201 and the second optical fiber winding area 202 of the second thin-walled cylinder 20. During winding, the winding starts from one end of the first optical fiber coupler 303 and the second optical fiber coupler 403, respectively. The optical fiber enters from the left threaded groove (or right threaded groove) of the sixth support rib 205, and the winding of the designed number of turns on the second optical fiber winding area 202 is completed in a uniform and dense manner. The optical fiber enters from the left threaded groove (or right threaded groove) of the fifth support rib 204. The groove (or right-hand threaded groove) enters the first optical fiber winding area 201, and is wound closely until the designed number of turns is completed. Then, starting from the current position, the next layer is wound in the reverse direction on the first optical fiber winding area 201. During the winding process, it enters the second optical fiber winding area 202 through the right-hand threaded groove (or left-hand threaded groove) of the fifth support rib 204. After completing the specified number of turns, it winds out of the second optical fiber winding area 202 through the right-hand threaded groove (or left-hand threaded groove) of the sixth support rib 205. The second Faraday rotator 307 at the end of the first long-arm sensing optical fiber 305 and the third Faraday rotator 406 at the end of the second short-arm sensing optical fiber 404 are glued to the inner wall of the first thin-walled cylinder 10.

[0042] In this embodiment, there are two optical fiber winding areas on the first thin-walled cylinder 10 and the second thin-walled cylinder 20; in some other embodiments, if it is necessary to increase sensitivity, the number of winding areas can be appropriately increased according to the actual situation.

[0043] In this embodiment, the optical fiber is wound with two layers; in other embodiments, if increased sensitivity is required, the number of winding layers can be appropriately increased according to the actual situation.

[0044] Furthermore, in this embodiment, the first optical input pigtail 301 of the first fiber interferometer 30 and the second optical input pigtail 401 of the second fiber interferometer 40 receive laser input, which is split into two beams by their respective fiber couplers. These beams then enter the short-arm sensing fiber and the long-arm sensing fiber of the two fiber interferometers, respectively. After being reflected by the Faraday rotator at the end of the sensing fiber, they return and converge at the fiber coupler to form interference light output. Under the action of the sound pressure signal, the first thin-walled cylinder 10 and the second thin-walled cylinder 20 simultaneously produce opposite radial deformations. Due to the adoption of the double push-pull structure, under the action of the thin-walled cylinder deformation... The first short-arm sensing fiber 304 of the first fiber interferometer 30 is lengthened (or shortened), and the first long-arm sensing fiber 305 is shortened (or lengthened) simultaneously. The second short-arm sensing fiber 404 of the second fiber interferometer 40 is shortened (or lengthened) simultaneously, and the second long-arm sensing fiber 405 is lengthened (or shortened) simultaneously. The output interference light of the first fiber interferometer 30 and the second fiber interferometer 40 respectively produces optical phase difference changes with equal amplitude and opposite phase. By performing differential calculation on the optical phase difference signals of the first fiber interferometer 30 and the second fiber interferometer 40, the sound pressure signal can be obtained.

[0045] Compared with the prior art, the fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression described in the above embodiments is superior because traditional fiber optic hydrophone sensitivity enhancement designs use ultra-long sensing fibers and the jitter of transmission optical cables and low-frequency noise from the light source are difficult to suppress. This invention features a simple structure and convenient operation. It employs a dual-fiber interferometer as the optical sensing element, forming a dual push-pull and differential detection structure. Under the influence of an acoustic signal, one arm of the sensing fiber of a single fiber interferometer extends while the other shortens, forming a single push-pull structure. The difference between these two arms is twice the deformation of the single-arm sensing fiber, thus increasing the relative deformation between the two sensing arms and enhancing the sensitivity of the fiber optic hydrophone. In this invention, the dual-fiber interferometer generates fiber deformations of equal magnitude but opposite directions, forming a dual push-pull structure. After differential calculation, the signal amplitude becomes twice that of a single fiber interferometer. Compared to traditional high-sensitivity single-fiber interferometer hydrophones using ultra-long sensing fibers, the length of each fiber interferometer sensing fiber is reduced to half that of a traditional single-fiber interferometer hydrophone, while maintaining the same sound pressure sensitivity. This reduces temperature drift and optical scattering noise caused by ultra-long sensing fibers in single-fiber interferometer hydrophones. Furthermore, the push-pull differential detection method of the dual-interferometer structure suppresses transmission cable jitter and low-frequency noise from the light source, achieving a reduction in background phase noise.

[0046] Obviously, the embodiments described above are merely preferred embodiments of this utility model, and not all embodiments. The accompanying drawings show preferred embodiments of this utility model, but do not limit the patent scope of this utility model. This utility model can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this utility model specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this utility model.

Claims

1. A fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression, characterized in that, include: A first thin-walled cylinder, a second thin-walled cylinder, a first fiber optic interferometer, and a second fiber optic interferometer; The first thin-walled cylinder is embedded in the second thin-walled cylinder, and the two form an air cavity. The first thin-walled cylinder is provided with a first optical fiber winding area and a second optical fiber winding area, and the second thin-walled cylinder is provided with a third optical fiber winding area and a fourth optical fiber winding area. The first fiber optic interferometer includes a first short-arm sensing fiber, a first long-arm sensing fiber, a first Faraday rotator, and a second Faraday rotator. The second fiber optic interferometer includes a second short-arm sensing fiber, a second long-arm sensing fiber, a third Faraday rotator, and a fourth Faraday rotator. The first short-arm sensing fiber is connected to the first Faraday rotator, the first long-arm sensing fiber is connected to the second Faraday rotator, the second short-arm sensing fiber is connected to the third Faraday rotator, and the second long-arm sensing fiber is connected to the fourth Faraday rotator. The first short-arm sensing fiber and the second long-arm sensing fiber are wound side-by-side on the first and second fiber winding areas. The first and fourth Faraday rotators are fixedly connected to the inner wall of the first thin-walled cylinder. The first long-arm sensing fiber and the second short-arm sensing fiber are wound side-by-side on the third and fourth fiber winding areas. The second and third Faraday rotators are fixedly connected to the inner wall of the first thin-walled cylinder.

2. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 1, characterized in that, The first thin-walled cylinder is also provided with a first supporting rib, a second supporting rib and a third supporting rib. The first supporting rib and the third supporting rib are respectively located at both ends of the first thin-walled cylinder, and the second supporting rib is located at the middle position of the first thin-walled cylinder.

3. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 2, characterized in that, The second thin-walled cylinder is also provided with a fourth support rib, a fifth support rib and a sixth support rib. The fourth support rib and the sixth support rib are respectively located at both ends of the second thin-walled cylinder, and the fifth support rib is located in the middle of the second thin-walled cylinder.

4. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 3, characterized in that, The outer diameters of the first, second, and third supporting ribs are the same, and they are also the same as the inner diameter of the second thin-walled cylinder.

5. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 4, characterized in that, The second, third, fifth, and sixth support ribs are each provided with left and right spiral grooves of the same pitch and depth, which are used to cross the support ribs and enter the adjacent optical fiber winding area during optical fiber winding.

6. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 1, characterized in that, The first fiber interferometer further includes a first fiber coupler, and the first short-arm sensing fiber and the first long-arm sensing fiber are respectively connected to the first fiber coupler.

7. A fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 6, characterized in that, The first fiber optic interferometer further includes a first optical input pigtail and a first optical output pigtail, which are respectively connected to the first fiber optic coupler.

8. The fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 1, characterized in that, The second fiber interferometer also includes a second fiber coupler, with the second short-arm sensing fiber and the second long-arm sensing fiber respectively connected to the second fiber coupler.

9. A fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 8, characterized in that, The second fiber interferometer also includes a second optical input pigtail and a second optical output pigtail, which are respectively connected to the second fiber coupler.

10. A fiber optic hydrophone with dual interferometer push-pull and common-mode noise differential suppression according to claim 1, characterized in that, The optical fiber is wound in two layers.

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