Optical fiber hydrophone based on double-cavity Fabry-Perot interferometer and manufacturing method thereof

Abstract

The invention discloses an optical fiber hydrophone based on a double-cavity Fabry-Perot interferometer and a manufacturing method of the optical fiber hydrophone, and belongs to the technical field of sensors, the optical fiber hydrophone comprises a double-hole quartz sleeve, one end of the double-hole quartz sleeve is of an open structure and is hermetically bonded with the edge of a composite diaphragm through uv glue; the other end of the double-hole quartz sleeve is provided with two through holes, and a single-mode optical fiber which is led into the double-hole quartz sleeve and is perpendicular to the composite membrane is inserted into each through hole; the inner side end faces of the two single-mode optical fibers are flush with each other and are bonded to the corresponding through holes through uv glue. According to the optical fiber hydrophone based on the double-cavity Fabry-Perot interferometer and the manufacturing method of the optical fiber hydrophone, the anti-interference performance can be effectively improved, and high-sensitivity detection of an underwater sound field can be highly stably achieved.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer and its fabrication method. Background Technology

[0002] Fiber Fabry-Perot (FP) sensors, based on the principle of multi-beam interference, modulate the optical path difference by varying the cavity length caused by external perturbations, thereby achieving signal detection. They possess the intrinsic characteristics of fiber optic sensors, such as high sensitivity, high resolution, and resistance to electromagnetic interference, and have broad application prospects in fields such as underwater acoustic detection and structural health monitoring. In recent years, researchers have mainly focused on optimizing diaphragm design and innovating demodulation algorithms to address the shortcomings of traditional fiber optic FP sensors in meeting emerging detection demands such as miniaturization, high sensitivity, and structural flexibility. Summary of the Invention

[0003] The purpose of this invention is to provide a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer and its fabrication method, which can effectively improve anti-interference performance and achieve highly sensitive underwater sound field detection with high stability.

[0004] To achieve the above objectives, the present invention provides a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer, comprising a double-hole quartz sleeve, one end of which is an open structure and sealed to the edge of a composite diaphragm with UV adhesive; the other end of the double-hole quartz sleeve has two through holes, each through hole having a single-mode optical fiber inserted into the double-hole quartz sleeve and perpendicular to the composite diaphragm; the inner end faces of the two single-mode optical fibers are flush and bonded to the corresponding through holes with UV adhesive.

[0005] Preferably, the composite film is a Si-Cr-Al composite film.

[0006] Preferably, the composite film has a Si layer thickness of 100 μm, a Cr layer thickness of 30 nm, and an Al layer thickness of 300 nm.

[0007] Preferably, the distance between the two through holes of the double-hole quartz sleeve is 1 mm.

[0008] This invention also provides a method for fabricating a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer, comprising the following steps: S1. A Cr-Al composite metal film is deposited on a silicon wafer substrate to form a composite film, and the protective layer on the surface of the composite film is removed. S2. Prepare two single-mode optical fibers. Cut the end faces of both single-mode optical fibers into flat surfaces using an optical fiber cleaver. Insert each single-mode optical fiber into a double-hole quartz sleeve through a through hole and fix them to the corresponding through holes with UV glue, ensuring that the end faces of the two single-mode optical fibers are in the same plane. S3. Use UV adhesive to bond the double-hole quartz sleeve to the center of the composite membrane, so that the two single-mode optical fibers in the quartz sleeve are perpendicular to the composite membrane. S4. Fix the double-hole quartz sleeve on the displacement platform, connect the two single-mode optical fibers to the fiber optic grating demodulator, move the displacement platform, first observe the spectral changes through the debugging software to ensure that the two spectra are the same, and finally cure with ultraviolet lamp to complete the fabrication of the sensor.

[0009] Preferably, in step S1, a 400μm silicon wafer is used as the substrate, and a Cr-Al based composite metal film is deposited on the silicon wafer using a vacuum magnetron sputtering process, so that the specified thickness of the Cr layer is 30nm and the specified thickness of the Al layer is 300nm; then, after exposure, development, and etching, the silicon wafer is etched to a thickness of 300μm; finally, the silicon wafer is cut into small pieces and immersed in an acetone solution to dissolve the protective layer, thus completing the separation of the composite film and the protective layer of the film.

[0010] Preferably, in S3, a thin layer of UV adhesive is applied to the top of the double-hole quartz sleeve and the composite diaphragm, so that the double-hole quartz sleeve is bonded close to the center of the composite diaphragm, ensuring that the two single-mode optical fibers in the double-hole quartz sleeve are perpendicular to the center of the composite diaphragm, so that the end faces of the two single-mode optical fibers and the two reflective surfaces between the composite diaphragm each form an FP cavity.

[0011] Therefore, the beneficial effects of the fiber optic hydrophone based on the dual-cavity Fabry-Perot interferometer and its fabrication method in this invention are as follows: (1) The fiber optic hydrophone adopts a dual fiber structure, which has higher stability and better anti-interference performance.

[0012] (2) Fiber optic hydrophones can efficiently convert underwater sound field signals into optical field signals, and have the characteristics of high signal-to-noise ratio and high sensitivity.

[0013] (3) Fiber optic hydrophones have better linearity and response amplitude at 100Hz.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the fiber optic hydrophone embodiment based on a dual-cavity Fabry-Perot interferometer of the present invention; Figure 2This is a step diagram illustrating the fabrication method of the fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer according to the present invention.

[0016] Figure Labels 1. Composite diaphragm; 2. Double-hole quartz sleeve; 3. Single-mode optical fiber. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0019] Example 1 like Figure 1 As shown, the present invention provides an optical fiber hydrophone based on a dual-cavity Fabry-Perot interferometer, including a double-hole quartz sleeve 2. One end of the double-hole quartz sleeve 2 is an open structure and is sealed and bonded to the edge of a composite diaphragm 1 with UV adhesive. The other end of the double-hole quartz sleeve 2 has two through holes, and the distance between the two through holes of the double-hole quartz sleeve 2 is 1 mm.

[0020] Each through hole is inserted with a single-mode optical fiber 3 that passes through the inside of the double-hole quartz sleeve 2 and is perpendicular to the composite diaphragm 1. This fiber is used to form an FP cavity with the composite diaphragm 1 to realize the conversion of acoustic signals to optical signals and to transmit optical signals.

[0021] The inner end faces of the two single-mode optical fibers 3 are flush and bonded to the corresponding through holes with UV adhesive, which helps to improve the stability of the sensor and the measurement accuracy.

[0022] Composite film 1 is a Si-Cr-Al composite film with a Si layer thickness of 100μm, a Cr layer thickness of 30nm, and an Al layer thickness of 300nm, balancing sensitivity and stability.

[0023] The above-mentioned method for fabricating a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer, such as... Figure 2 As shown, it includes the following steps: S1. A Cr-Al composite metal film is deposited on a silicon wafer substrate to form a composite film 1, and the protective layer on the surface of the composite film is removed, specifically: Using a 400μm silicon wafer as the substrate, a Cr-Al based composite metal film was deposited on the silicon wafer using vacuum magnetron sputtering, with a specified thickness of 30nm for the Cr layer and 300nm for the Al layer. Then, the silicon wafer was etched to a thickness of 300μm through a series of processes including exposure, development, and etching. Finally, the silicon wafer was cut into small pieces with a diameter of 2.5mm to complete the initial processing. Afterwards, composite film 1 was immersed in an acetone solution to dissolve the protective layer for approximately 12 hours, completing the separation of composite film 1 and the protective layer.

[0024] S2. Prepare two single-mode optical fibers 3. Cut the end faces of the two single-mode optical fibers 3 into flat surfaces using an optical fiber cleaver. Insert the two single-mode optical fibers 3 into the double-hole quartz sleeve 2 through a through hole and fix them to the corresponding through holes with UV glue, ensuring that the end faces of the two single-mode optical fibers 3 are in the same plane.

[0025] S3. The double-hole quartz sleeve 2 is bonded to the center of the composite diaphragm 1 using UV adhesive, so that the two single-mode optical fibers 3 in the quartz sleeve 2 are perpendicular to the composite diaphragm 1, specifically: A thin layer of UV adhesive is applied to the top of the double-hole quartz sleeve 2 and near the center of the composite diaphragm 1, ensuring the adhesive is as thin as possible to eliminate its impact on the cavity length after curing. The double-hole quartz sleeve 2 is then bonded close to the center of the composite diaphragm 1, ensuring that the two single-mode optical fibers 3 in the double-hole quartz sleeve 2 are perpendicular to the center of the composite diaphragm 1, so that the end faces of the two single-mode optical fibers 3 and the two reflective surfaces between the composite diaphragm 1 each form an FP cavity.

[0026] S4. Fix the double-hole quartz sleeve 2 on the displacement platform, connect the two single-mode optical fibers 3 to the fiber optic demodulator, move the displacement platform, first observe the spectral changes through the debugging software to ensure that the two spectra are the same, and finally cure with ultraviolet lamp to complete the fabrication of the sensor.

[0027] The sensor works as follows: two single-mode optical fibers 3 form two equal-length FP cavities between their end faces and the composite diaphragm 1, with the cavity length set to L, thus constituting two symmetrical interference cavities. Under the influence of changes in external sound pressure, the composite diaphragm 1 undergoes minute vibrations, with the displacement of its center set to ΔL, causing changes in the optical path length of the two interference cavities. This ultimately forms interference fringes at the detector end, and the external sound field signal can be obtained by demodulating the interference signal.

[0028] Therefore, the fiber optic hydrophone based on the dual-cavity Fabry-Perot interferometer and its manufacturing method described above can effectively improve anti-interference performance and achieve highly sensitive underwater sound field detection with high stability.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer, characterized in that: The device includes a double-hole quartz sleeve, one end of which is open and sealed to the edge of a composite diaphragm with UV adhesive; the other end of the double-hole quartz sleeve has two through holes, each of which is inserted with a single-mode optical fiber that passes through the double-hole quartz sleeve and is perpendicular to the composite diaphragm; the inner end faces of the two single-mode optical fibers are flush and are both bonded to the corresponding through holes with UV adhesive.

2. The fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer according to claim 1, characterized in that: The composite membrane is a Si-Cr-Al composite membrane.

3. The fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer according to claim 2, characterized in that: The composite film has a Si layer thickness of 100 μm, a Cr layer thickness of 30 nm, and an Al layer thickness of 300 nm.

4. The fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer according to claim 1, characterized in that: The distance between the two through holes of the double-hole quartz sleeve is 1 mm.

5. A method for fabricating a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer, characterized in that, Includes the following steps: S1. A Cr-Al composite metal film is deposited on a silicon wafer substrate to form a composite film, and the protective layer on the surface of the composite film is removed. S2. Prepare two single-mode optical fibers. Cut the end faces of both single-mode optical fibers into flat surfaces using an optical fiber cleaver. Insert each single-mode optical fiber into a double-hole quartz sleeve through a through hole and fix them to the corresponding through holes with UV glue, ensuring that the end faces of the two single-mode optical fibers are in the same plane. S3. Use UV adhesive to bond the double-hole quartz sleeve to the center of the composite membrane, so that the two single-mode optical fibers in the quartz sleeve are perpendicular to the composite membrane. S4. Fix the double-hole quartz sleeve on the displacement platform, connect the two single-mode optical fibers to the fiber optic grating demodulator, move the displacement platform, first observe the spectral changes through the debugging software to ensure that the two spectra are the same, and finally cure with ultraviolet lamp to complete the fabrication of the sensor.

6. The method for fabricating a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer according to claim 5, characterized in that: In S1, a 400μm silicon wafer is used as the substrate. A Cr-Al based composite metal film is deposited on the silicon wafer using a vacuum magnetron sputtering process, with a specified thickness of 30nm for the Cr layer and 300nm for the Al layer. Then, after exposure, development, and etching, the silicon wafer is etched to a thickness of 300μm. Finally, the silicon wafer is cut into small pieces and immersed in an acetone solution to dissolve the protective layer, thus completing the separation of the composite film and the protective layer.

7. The method for fabricating a fiber optic hydrophone based on a dual-cavity Fabry-Perot interferometer according to claim 5, characterized in that: In S3, a thin layer of UV adhesive is applied to the top of the double-hole quartz sleeve and the composite diaphragm, so that the double-hole quartz sleeve is bonded close to the center of the composite diaphragm. This ensures that the two single-mode optical fibers in the double-hole quartz sleeve are perpendicular to the center of the composite diaphragm, so that the end faces of the two single-mode optical fibers and the two reflective surfaces between the composite diaphragm each form an FP cavity.

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