Optical Fiber Sensor Based on Polymer Film and Polymer Microcavity and Manufacturing Method

Abstract

The present invention provides an optical fiber sensor based on a polymer thin film and a polymer microcavity and a manufacturing method thereof. The sensor includes a polymer support and a quartz optical fiber for transmitting signals. The polymer support has a cavity. One end of the polymer support is connected to one end of the quartz optical fiber through a polymer adhesive to form a polymer microcavity. A polymer thin film is provided near the other end of the polymer support in the polymer microcavity. A first reflective film is plated on one end face of the quartz optical fiber, and a second reflective film is plated on the surface of the polymer thin film. The first reflective film and the second reflective film are arranged opposite to each other to form two emission surfaces of the polymer microcavity. The method of the present invention is applied to the above optical fiber sensor. The thin film and the microcavity designed based on polymer materials in the present invention have a low Young's modulus and have ultra-high sensitivity to external ultrasonic signals.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to an optical fiber sensor based on a polymer thin film and a polymer microcavity, and a manufacturing method applied to the sensor. Background Art

[0002] Compared with electrical ultrasonic sensors, optical fiber sensors have many advantages, such as being immune to electromagnetic interference, having higher sensitivity, smaller size, being passive, etc., and have attracted much attention.

[0003] Currently, ultrasonic sensors based on pure quartz optical fibers are restricted by the Young's modulus of quartz itself. Although the sensitivity can be improved through some special structural designs, such as high-order mode interference or special thin film microcavity designs, the improvement in ultrasonic sensitivity to the outside world is limited. Summary of the Invention

[0004] The main object of the present invention is to provide an optical fiber sensor based on a polymer thin film and a polymer microcavity, which has a lower Young's modulus and has ultra-high sensitivity to external ultrasound.

[0005] Another object of the present invention is to provide a manufacturing method for the above-mentioned optical fiber sensor based on a polymer thin film and a polymer microcavity.

[0006] To achieve the above main object, an optical fiber sensor based on a polymer thin film and a polymer microcavity provided by the present invention includes a polymer support and a quartz optical fiber for transmitting signals. The polymer support has a cavity. One end of the polymer support is connected to one end of the quartz optical fiber through a polymer adhesive to form a polymer microcavity. A polymer thin film is provided near the other end of the polymer support in the polymer microcavity; a first reflective film is plated on one end face of the quartz optical fiber, and a second reflective film is plated on the surface of the polymer thin film. The first reflective film and the second reflective film are arranged opposite to each other to form two emission surfaces of the polymer microcavity.

[0007] In a further aspect, the polymer thin film is clamped on the polymer support through a polymer adhesive.

[0008] In a further aspect, the thickness of the polymer support is greater than 1 mm.

[0009] In a further aspect, the thickness of the polymer thin film is 30 - 80 μm.

[0010] In a further aspect, the thickness of the polymer thin film is 50 μm.

[0011] In a further aspect, the reflectivity of the first reflective film is 4% - 50%.

[0012] In a further embodiment, the reflectivity of the second reflective film is greater than 70%, and the thickness is greater than 200 nm.

[0013] In a further embodiment, the size of the polymer microcavity is 325 μm in length and 1.25 mm in inner diameter.

[0014] To achieve the above-mentioned another object, the present invention provides a method for manufacturing an optical fiber sensor based on a polymer thin film and a polymer microcavity. The optical fiber sensor is the above-mentioned optical fiber sensor. The method includes the following steps: depositing a first reflective film on the end face of the optical fiber with a ceramic ferrule, controlling its thickness to be less than 200 nm, as the first reflective surface of the polymer microcavity; providing a polymer bracket with an outer diameter of 1.26 - 1.30 mm, providing a polymer thin film with a thickness of 30 - 80 μm, depositing a second reflective film on the surface of the polymer thin film, controlling its thickness to be greater than 200 nm, as the second reflective surface of the polymer microcavity; using a polymer adhesive to sandwich the polymer thin film between the polymer brackets; sleeving the polymer bracket with the polymer thin film on the optical fiber and fixing it with a polymer adhesive, then an optical fiber sensor based on a polymer thin film and a polymer microcavity can be obtained.

[0015] In a further embodiment, a polymer bracket with an outer diameter of 1.26 - 1.30 mm is fabricated by using a light-curing 3D printing technology. The thickness of the polymer bracket is greater than 1 mm, the inner cavity diameter of the polymer bracket is 1.25 mm, the materials on the upper and lower sides of the polymer bracket are removed to obtain grooves, the polymer thin film is embedded in the grooves on both sides of the polymer bracket, and fixed with a polymer adhesive.

[0016] Thus, based on the structural design of fusing a polymer thin film with a polymer microcavity, the present invention forms two reflective surfaces of the microcavity by the emission film and the end face of the quartz optical fiber. When the external ultrasound acts on the microcavity, the quartz optical fiber and the polymer thin film will simultaneously respond to the external vibration. The combined response of the two will cause corresponding changes in the diameter and length of the cylindrical microcavity. This change will directly lead to a change in the cavity length of the microcavity, thereby causing a dynamic drift in the emission spectrum of the microcavity.

[0017] Therefore, based on the thin film and microcavity designed with polymer materials and combining the unique advantages of the optical fiber sensor, the present invention proposes a polymer-based optical fiber ultrasonic sensor with high sensitivity, which has a small Young's modulus and ultra-high sensitivity to external ultrasonic signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of an embodiment of an optical fiber sensor based on a polymer thin film and a polymer microcavity of the present invention.

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed implementation mode

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0021] An embodiment of an optical fiber sensor based on a polymer thin film and a polymer microcavity:

[0022] See Figure 1 , an optical fiber sensor based on a polymer thin film and a polymer microcavity of the present invention, which includes a polymer bracket 20 and a quartz optical fiber 10 for transmitting signals. The polymer bracket 20 has a cavity. One end of the polymer bracket 20 is connected to one end of the quartz optical fiber 10 through a polymer adhesive to form a polymer microcavity 50. A polymer thin film 30 is provided near the other end of the polymer bracket 20 in the polymer microcavity 50.

[0023] In this embodiment, a first reflective film 11 is plated on one end face of the quartz optical fiber 10, and a second reflective film 31 is plated on the surface of the polymer thin film 30. The first reflective film 11 and the second reflective film 31 are oppositely arranged to form two emission surfaces of the polymer microcavity 50.

[0024] In this embodiment, the polymer thin film 30 is clamped on the polymer bracket 20 through a polymer adhesive. Among them, the polymer adhesive in this embodiment is preferably epoxy resin or polypropionate. It can be seen that the polymer thin film 30 is clamped on the bracket by means of polymer bonding. The polymer bracket 20 plays a role in pulling the polymer thin film 30 closer and at the same time serves as an effective support for the cavity.

[0025] In this embodiment, the thickness of the polymer bracket 20 is greater than 1 mm. Among them, the thickness of the polymer bracket 20 is greater than 1 mm and less than 10 mm, which is suitable for a cylindrical structure and mainly forms the bracket of the polymer microcavity 50.

[0026] In this embodiment, the reflectivity of the first reflective film 11 is 4%-50%.

[0027] In this embodiment, the thickness of the polymer thin film 30 is 30-80 um. Among them, the thickness of the polymer thin film 30 is 50 um.

[0028] In this embodiment, the reflectivity of the second reflective film 31 is greater than 70% and less than 90%, and the thickness is greater than 200 nm. It can be seen that the thickness of the polymer film 30 is controlled at about 50 μm, and an emission film with a thickness greater than 200 nm and less than 500 nm is plated on its surface. The materials of the first reflective film 11 and the second reflective film 31 can be aluminum, silver, or gold.

[0029] In this embodiment, the size of the polymer microcavity 50 is 325 μm in length and 1.25 mm in inner diameter.

[0030] Specifically, the structure of the sensor is a microcavity based on the polymer support 20. A reflective film is plated on the polymer film 30 and supported and tightened by the polymer support 20. The film facing the end face of the quartz optical fiber 10 is plated with a reflective film with an emissivity greater than 70% (the material can be aluminum, silver, gold, etc.). The polymer support 20 has a relatively thick thickness for supporting the polymer film 30. The polymer support 20 and the quartz optical fiber 10 are bonded together by a polymer adhesive. The size of the cavity is controlled at about 130 μm. The design of such a cavity can be realized by high-precision 3D printing technology, femtosecond laser writing technology, or ion beam etching technology.

[0031] An embodiment of a manufacturing method of an optical fiber sensor based on a polymer film 30 and a polymer microcavity 50:

[0032] A manufacturing method of an optical fiber sensor based on a polymer film 30 and a polymer microcavity 50 provided by the present invention. The optical fiber sensor is the above-mentioned optical fiber sensor. The method includes the following steps:

[0033] Plating a first reflective film 11 on the end face of the optical fiber with a ceramic ferrule, controlling its thickness to be less than 200 nm as the first reflective surface of the polymer microcavity 50; providing a polymer support 20 with an outer diameter of 1.26 - 1.30 mm, providing a polymer film 30 with a thickness of 30 - 80 μm, plating a second reflective film 31 on the surface of the polymer film 30, controlling its thickness to be greater than 200 nm as the second reflective surface of the polymer microcavity 50; using a polymer adhesive to sandwich the polymer film 30 between the polymer supports 20; sleeving the polymer support 20 with the polymer film 30 on the optical fiber and fixing it with a polymer adhesive, then an optical fiber sensor based on the polymer film 30 and the polymer microcavity 50 can be obtained.

[0034] Furthermore, use a photocuring 3D printing technology to fabricate a polymer support 20 with an outer diameter of 1.26 - 1.30 mm. The polymer support 20 has a thickness greater than 1 mm, and the inner cavity diameter of the polymer support 20 is 1.25 mm. Remove materials from the upper and lower sides of the polymer support 20 to obtain grooves, embed the polymer film 30 into the grooves on both sides of the polymer support 20, and fix it with a polymer adhesive.

[0035] In practical applications, a metal aluminum (silver or gold) reflective film is first deposited on the end face of the optical fiber with a ceramic ferrule, and the thickness is controlled to be less than 200 nm, serving as the first reflective surface of the microcavity.

[0036] A polymer support 20 with an outer diameter of 1.26 mm is fabricated using a light-curing 3D printing technique, and then a polymer thin film 30 is fixed and pulled closer using a polymer colloid (epoxy resin or polypropionate).

[0037] Then, the microcavity with the polymer thin film 30 and an inner diameter of 1.26 mm is directly sleeved on the optical fiber, and the microcavity is fixed using a polymer colloid (epoxy resin or polypropionate).

[0038] It can be seen that based on the structural design of the polymer microcavity 50 integrating the polymer thin film 30, the emission film and the end face of the quartz optical fiber 10 form the two reflective surfaces of the microcavity. When external ultrasound acts on the microcavity, the quartz optical fiber 10 and the polymer thin film 30 will simultaneously respond to the external vibration. The common response of the two will cause corresponding changes in the diameter and length of the cylindrical microcavity. This change will directly lead to a change in the cavity length of the microcavity, thereby causing a dynamic drift in the emission spectrum of the microcavity.

[0039] Therefore, based on the thin film and microcavity designed with polymer materials and combining the unique advantages of fiber optic sensors, the present invention proposes a polymer-based fiber optic ultrasonic sensor with high sensitivity, having a small Young's modulus and extremely high sensitivity to external ultrasonic signals.

[0040] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0041] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0042] It should be noted that the above are only the preferred embodiments of the present invention, but the design concept of the invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept also fall within the protection scope of the present invention.

Claims

1. An optical fiber sensor based on a polymer thin film and a polymer microcavity, characterized in that, Comprising: A polymer support and a quartz optical fiber for transmitting signals. The polymer support has a cavity. One end of the polymer support is connected to one end of the quartz optical fiber through a polymer adhesive to form a polymer microcavity. A polymer thin film is provided near the other end of the polymer support within the polymer microcavity. A first reflective film is deposited on one end face of the quartz optical fiber, and a second reflective film is deposited on the surface of the polymer thin film. The first reflective film and the second reflective film are oppositely arranged to form two emitting surfaces of the polymer microcavity. A method for fabricating an optical fiber sensor based on a polymer thin film and a polymer microcavity includes: Depositing a first reflective film on the end face of an optical fiber with a ceramic ferrule, controlling its thickness to be less than 200 nm, as the first reflective surface of the polymer microcavity. Providing a polymer support with an outer diameter of 1.26 - 1.30 mm, providing a polymer thin film with a thickness of 30 - 80 μm, depositing a second reflective film on the surface of the polymer thin film, controlling its thickness to be greater than 200 nm, as the second reflective surface of the polymer microcavity. Clamping the polymer thin film between the polymer supports using a polymer adhesive. Sleeving the polymer support with the polymer thin film on the optical fiber and fixing it through the polymer adhesive to obtain an optical fiber sensor based on the polymer thin film and the polymer microcavity. Fabricating a polymer support with an outer diameter of 1.26 - 1.30 mm using a light-curing 3D printing technique. The thickness of the polymer support is greater than 1 mm, the inner cavity diameter of the polymer support is 1.25 mm. Removing materials from the upper and lower sides of the polymer support to obtain grooves, embedding the polymer thin film into the grooves on both sides of the polymer support, and fixing it using a polymer adhesive.

2. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to claim 1, wherein: The polymer thin film is clamped on the polymer support through a polymer adhesive.

3. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to claim 1, wherein: The thickness of the polymer support is greater than 1 mm.

4. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to claim 1, wherein: The thickness of the polymer thin film is 30 - 80 μm.

5. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to claim 4, wherein: The thickness of the polymer thin film is 50 μm.

6. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to any one of claims 1 to 5, wherein: The reflectivity of the first reflective film is 4% - 50%.

7. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to any one of claims 1 to 5, wherein: The reflectivity of the second reflective film is greater than 70%, and the thickness is greater than 200 nm.

8. The optical fiber sensor based on a polymer thin film and a polymer microcavity according to any one of claims 1 to 5, wherein: The size of the polymer microcavity is 325 μm in length and 1.25 mm in inner diameter.

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