Grating sensitization structure, preparation method thereof and optical fiber sensor

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a grating sensitization structure, a preparation method thereof and an optical fiber sensor. The preparation method comprises the following steps: removing a cladding with a preset length and a preset height from an optical fiber by adopting a side polishing process; forming a side parabolic surface and an annular surface, and etching a plurality of grooves in the annular surface; plating a metal film on the annular surface; and preparing a Pt / WO3 film on the metal film and the side polished surface to obtain the grating sensitization structure. According to the preparation method, the Pt / WO3 thin film is used as a hydrogen-sensitive material, when the hydrogen concentration changes, the Pt / WO3 thin film absorbs hydrogen and releases heat, the temperature of the grating is increased, the metal thin film expands and deforms due to the heat effect, the grating is pulled to generate strain, and the response of the optical fiber sensor to the hydrogen concentration change is increased. Meanwhile, the grating is laterally thrown to form a D-shaped structure, and the stress on the two sides of the grating is not uniform, so that the grating is bent, the strain effect is enhanced, and the sensitivity of the optical fiber sensor is further enhanced.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensing technology, and in particular to a grating sensitivity enhancement structure and a preparation method thereof, and an optical fiber sensor. Background Art

[0002] As a clean energy, hydrogen is increasingly used. Due to its high flammability and explosiveness, hydrogen leak detection has become crucial in the field of hydrogen applications. Therefore, the development of highly sensitive and highly selective hydrogen sensors is of great significance for ensuring industrial safety and environmental monitoring. Although traditional hydrogen detection sensors, such as electrochemical sensors and metal oxide semiconductor sensors, have shown good performance in certain applications, they usually have limitations such as long response time, poor selectivity, and susceptibility to environmental factors.

[0003] Therefore, fiber optic sensors are usually used in hydrogen detection. With their unique optical properties, such as anti-electromagnetic interference, high sensitivity, and remote monitoring capabilities, fiber optic sensors have shown great potential in the field of gas detection. In particular, fiber Bragg Grating (FBG) sensors are considered to be an ideal hydrogen detection sensor due to their small size, easy integration, and multi-parameter simultaneous detection. However, in the process of hydrogen detection, fiber optic sensors still cannot avoid problems such as low sensitivity, poor stability, and poor long-term reliability.

[0004] Therefore, there is an urgent need for an optical fiber sensor with high sensitivity, stability and long-term reliability. Summary of the invention

[0005] The present application provides a grating sensitization structure and a preparation method thereof, and an optical fiber sensor to solve the technical problems of low sensor sensitivity, poor stability and long-term reliability in the hydrogen detection process.

[0006] The first aspect of the present application provides a method for preparing a grating sensitivity enhancement structure, comprising: using a side polishing process to remove a cladding of a preset length and a preset height on an optical fiber; wherein the optical fiber after removal includes a side polished surface and an annular surface, the side polished surface is formed by side polishing, the side polished surface covers the grating of the optical fiber, the preset length is greater than the length of the entire grating, and the cross-sectional shape of the grating after removing the cladding is D-shaped; etching a plurality of grooves on the annular surface; wherein the plurality of grooves are arranged in sequence along the length direction of the optical fiber; coating a metal film on the annular surface; wherein the metal film covers the plurality of grooves; preparing a Pt / WO3 film on the metal film and the side polished surface to obtain a grating sensitivity enhancement structure.

[0007] In some possible implementations, the groove is a spiral groove.

[0008] In some possible implementations, the groove is a straight groove.

[0009] In some feasible implementations, the depth of the groove is 3-10 μm.

[0010] In some feasible implementations, the preset height is 1 / 5 to 1 / 3 of the optical fiber diameter.

[0011] In some feasible implementations, the metal film is a copper film; the metal film is plated on the annular surface, including: using a magnetron sputtering method to plate a first copper film on the annular surface; using an electroplating method to plate a second copper film on the first copper film; wherein the thickness of the first copper film is less than the thickness of the second copper film.

[0012] In some feasible implementations, the thickness of the first copper film is 80-120 nm, and the thickness of the second copper film is 10-50 μm.

[0013] In some feasible implementations, the Pt / WO3 thin film is prepared by a sol-gel method through C 10 H 14 O4Pt and WO3 were prepared, and the thickness of Pt / WO3 film was 2~30μm.

[0014] The preparation method of the grating sensitivity enhancement structure provided in the first aspect of the present application uses a Pt / WO3 film as a hydrogen-sensitive material. When the hydrogen concentration changes, the Pt / WO3 film absorbs hydrogen and releases heat, causing the grating temperature to rise. The metal film expands and deforms due to the thermal effect, pulling the grating to produce strain, thereby increasing the response of the optical fiber sensor to changes in hydrogen concentration, thereby increasing the sensitivity of the optical fiber sensor. At the same time, the grating is side-cast to form a D-shaped structure, and the force on both sides of the grating is uneven, causing the grating to bend, enhancing the strain effect, and further enhancing the sensitivity of the optical fiber sensor.

[0015] The grating sensitivity enhancement structure provided in the second aspect of the present application is prepared by the preparation method of the grating sensitivity enhancement structure provided in the first aspect, and the grating sensitivity enhancement structure includes a D-type grating, which is arranged on an optical fiber; wherein the cross-sectional shape of the D-type grating is D-shaped, and the D-type grating is obtained by removing a cladding of a preset length and a preset height from the optical fiber through a side polishing process, and the D-type grating includes a side polished surface and an annular surface, and the side polished surface is formed by side polishing; a plurality of grooves are arranged on the annular surface; wherein the plurality of grooves are arranged in sequence along the length direction of the optical fiber; a metal film is covered on the annular surface; wherein the metal film covers the plurality of grooves; a Pt / WO3 film is covered on the metal film and the side polished surface.

[0016] The grating sensitivity enhancement structure provided in the second aspect of the present application is prepared by the preparation method of the grating sensitivity enhancement structure provided in the first aspect. Therefore, its beneficial technical effects can be referred to the first aspect and will not be repeated here.

[0017] The optical fiber sensor provided in the third aspect of the present application includes the grating sensitivity enhancement structure provided in the second aspect.

[0018] The optical fiber sensor provided in the third aspect of the present application includes the grating sensitivity enhancement structure provided in the second aspect, and the grating sensitivity enhancement structure provided in the second aspect is prepared by the preparation method of the grating sensitivity enhancement structure provided in the first aspect. Therefore, the beneficial technical effects of the optical fiber sensor provided in the third aspect can be referred to the first aspect and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 It is a schematic diagram of the structure of an optical fiber provided in an embodiment of the present application; Figure 2 It is a schematic flow chart of a method for preparing a grating sensitivity enhancement structure provided in an embodiment of the present application; Figure 3 It is a schematic diagram of the structure of a grating after side-casting provided in an embodiment of the present application; Figure 4 is a schematic diagram of the structure of a groove provided in an embodiment of the present application; Figure 5 is a schematic diagram of the structure of another groove provided in an embodiment of the present application; Figure 6 This is a schematic diagram of a structure after a metal film is plated provided in an embodiment of the present application; Figure 7 This is a schematic diagram of the structure of a Pt / WO3 thin film after preparation provided in an embodiment of the present application; Figure 8 It is a structural schematic diagram of a grating sensitivity enhancement structure provided in an embodiment of the present application.

[0021] Graphic marking: 1-optical fiber; 10-grating; 101-side polishing surface; 101a-first connection; 101b-second connection; 102-annular surface; 103-groove; 104-metal film; 104a-first copper film; 104b-second copper film; 105-Pt / WO3 film; 20-core; 30-cladding. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making creative work all belong to the protection scope of the present application.

[0023] In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0024] In addition, in the present application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to the changes in the orientation of the components placed in the drawings.

[0025] In order to solve the problems of low sensitivity, poor stability and long-term reliability of optical fiber sensors in detecting hydrogen, the embodiment of the present application provides a method for preparing a grating sensitivity enhancement structure. The preparation method prepares a grating with a D-shaped cross-sectional shape through innovative design and process, and prepares a groove structure on the annular surface of the D-shaped grating. The grating is applied in an optical fiber sensor, which effectively improves the performance of the optical fiber sensor, can improve its detection sensitivity to hydrogen, and can be widely used in industrial and environmental detection.

[0026] The specific structure of the optical fiber is briefly described below.

[0027] See also Figure 1 The embodiment of the present application provides a fiber Bragg grating, which can periodically modulate the refractive index of the fiber core so that light of a specific wavelength is reflected in the fiber, thereby screening out a specific optical signal and transmitting light of other wavelengths. The optical fiber 1 includes a core 20, a grating 10 prepared on the core 20, and a cladding 30 sleeved outside the core 20. The total length of the grating 10 is L0.

[0028] The method for preparing the grating sensitivity enhancement structure provided in the embodiment of the present application can be implemented by the following steps S100 to S400.

[0029] Combination Figure 2 and Figure 3 , step S100: using a side-throwing process to remove the cladding 30 of a preset length and a preset height on the optical fiber 1.

[0030] Before executing step S100, the optical fiber 1 may be pre-processed to ensure that the surface of the optical fiber 1 is clean and free of impurities.

[0031] In step S100, a side-throwing process is used to remove part of the cladding 30 along the length direction of the optical fiber 1. The length of the removed part of the cladding 30 is a preset length L, and the height is a preset height H. The preset length L is greater than the length L0 of the entire grating 10, and the removed part covers the entire grating 10. In other words, the cladding 30 greater than the length of the grating 10 is removed along the extension direction of the grating 10 by the side-throwing process, wherein the projection of the removed part in the vertical direction covers the entire grating 10.

[0032] The side polishing process is performed along the length direction of the optical fiber 1. That is, after the side polishing, a side polishing surface 101 can be obtained, and the side polishing surface 101 covers the grating 10. When the optical fiber 1 is in a horizontal state, the side polishing surface 101 is parallel to the horizontal plane. The remaining part of the grating 10 after the side polishing is an annular surface 102, so that the length of the side polishing surface 101 and the annular surface 102 is also L, and the cross-sectional shape of the grating 10 formed by the side polishing surface 101 and the annular surface 102 is D-shaped.

[0033] In some feasible implementations, the preset height H of the cladding 30 removed by side casting is 1 / 5 to 1 / 3 of the diameter H0 of the optical fiber 1. For example, the preset height H can be 1 / 5 of the diameter H0 of the optical fiber 1, or 1 / 3 of the diameter H0 of the optical fiber 1. Of course, the preset height H can also be other values ​​between 1 / 5 and 1 / 3.

[0034] Likewise, the height H of the remaining portion of the grating 10 is 2 / 3 to 4 / 5 of the diameter H0 of the optical fiber 1 .

[0035] Continue to combine Figure 2 , Figure 3 and Figure 4 , step S200: etching a plurality of grooves 103 on the annular surface 102 .

[0036] In step S200, a femtosecond laser may be used to etch a plurality of grooves 103 on the annular surface 102, and the plurality of grooves 103 are arranged in sequence along the length direction of the optical fiber 1. The side-polished surface 101 formed by side-polishing and the annular surface 102 have two connections, namely, a first connection 101a and a second connection 101b. The first connection 101a and the second connection 101b are respectively located on both sides of the side-polished surface 101. When etching the grooves 103, the first connection 101a may be used as a starting point, and a groove 103 having a preset depth is etched along the annular surface 102, and the groove 103 is etched along the annular surface 102 to the second connection 101b. The positions of the first connection 101a and the second connection 101b are not fixed, and in other implementations, the positions of the first connection 101a and the second connection 101b may be interchangeable.

[0037] In some feasible implementations, the depth of the groove 103 may be 3-10 μm.

[0038] For example, the depth of the groove 103 may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm. Of course, the depth of the groove 103 may also be other values ​​between 3 and 10 μm.

[0039] In a specific implementation, the depth of the groove 103 may be 4.5 μm.

[0040] It is worth noting that the groove width of the groove 103, the distance between any two adjacent grooves 103, and the number of grooves 103 can be adjusted according to the preset length L. For example, when the preset length L is relatively long, the groove 103 can adopt a larger groove width, the distance between any two adjacent grooves 103 can be increased, and the number of grooves 103 can be increased. For example, when the preset length L is relatively short, the groove 103 can adopt a smaller groove width, the distance between any two adjacent grooves 103 can be reduced, and the number of grooves 103 can be reduced. The embodiment of the present application does not specifically limit the groove width of the groove 103, the distance between any two adjacent grooves 103, and the number of grooves 103.

[0041] In a specific implementation, see Figure 4 The groove 103 may be a spiral groove, in which case the groove 103 is spirally arranged along the length direction of the optical fiber 1 .

[0042] In a specific implementation, see Figure 5 The groove 103 may be a straight groove, in which case the groove 103 is arranged parallel to the length direction of the optical fiber 1 .

[0043] Of course, in other specific implementations, the groove 103 may also take other forms, and the embodiment of the present application does not specifically limit the form of the groove 103.

[0044] in, Figure 4 and Figure 5 The number of the grooves 103 shown is three and is only an example.

[0045] Combination Figure 2 and Figure 6 , step S300: coating a metal film 104 on the annular surface 102 .

[0046] The metal film 104 covers the plurality of grooves 103. The metal film 104 is plated to ensure tight coupling between the metal film 104 and the grooves 103, thereby ensuring the long-term stability of the optical fiber sensor.

[0047] In some feasible implementations, the metal film 104 may be a copper film, and step S300 may be implemented by the following steps S301 and S302 .

[0048] Step S301: a first copper film 104 a is plated on the annular surface 102 by a magnetron sputtering method.

[0049] The first copper film 104 a is plated on the annular surface 102 as a conductive layer.

[0050] In some feasible implementations, the thickness of the first copper film 104a may be 80-120 nm. For example, the thickness of the first copper film 104a may be one of 80 nm, 90 nm, 100 nm, 110 nm, or 120 nm. Of course, the thickness of the first copper film 104a may also be other values ​​between 80-120 nm.

[0051] In a specific implementation, the thickness of the first copper film 104a may be 105 nm.

[0052] Step S302: electroplating a second copper film 104b on the first copper film 104a.

[0053] The thickness of the first copper film 104a is smaller than the thickness of the second copper film 104b.

[0054] In some feasible implementations, the thickness of the second copper film 104b may be 10-50 μm. For example, the thickness of the second copper film 104b may be one of 10 μm, 20 μm, 30 μm, 40 μm or 50 μm. Of course, the thickness of the second copper film 104b may also be other values ​​in the range of 10-50 μm.

[0055] In a specific implementation, the thickness of the second copper film 104b may be 25 μm.

[0056] It is worth noting that in the above implementation, the metal film 104 can be a copper film, and in other specific implementations, metal films of other materials can also be used.

[0057] Combination Figure 2 and Figure 7 , step S400: preparing a Pt / WO3 film 105 on the metal film 104 and the side polished surface 101 to obtain a grating sensitivity enhancement structure.

[0058] In step S400, the Pt / WO3 film 105 can be prepared by a sol-gel method by platinum (II) acetylacetonate (C 10 H 14 O4Pt) ​​and WO3.

[0059] In some feasible implementations, the thickness of the Pt / WO3 film 105 may be 2-30 μm. For example, the thickness of the Pt / WO3 film 105 may be one of 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm or 30 μm. Of course, the thickness of the Pt / WO3 film 105 may also be other values ​​in the range of 2-30 μm.

[0060] In a specific implementation, the thickness of the Pt / WO 3 film 105 may be 5.5 μm.

[0061] Among them, in the embodiment of the present application, Pt / WO3 film 105 is used as a hydrogen-sensitive material. When the hydrogen concentration changes, the Pt / WO3 film 105 absorbs hydrogen and releases heat, causing the temperature of the grating 10 to rise. The first copper film 104a and the second copper film 104b expand and deform due to the thermal effect, pulling the grating 10 to produce strain, thereby increasing the response of the optical fiber sensor to the change in hydrogen concentration, thereby increasing the sensitivity of the optical fiber sensor. At the same time, the grating 10 is side-cast to form a D-type structure. During the process of the Pt / WO3 film 105 absorbing hydrogen and releasing heat, the grating 10 is bent due to the uneven force on both sides of the grating 10, thereby enhancing the strain effect, thereby further enhancing the sensitivity of the optical fiber sensor. Moreover, by processing the groove 103 on the optical fiber cladding 30, the first copper film 104a and the second copper film 104b are ensured to be tightly combined with the optical fiber 1, thereby enhancing the long-term reliability of the optical fiber sensor.

[0062] In order to better understand the grating sensitivity enhancement structure prepared in the embodiment of the present application, the process of increasing the sensitivity of the optical fiber sensor by the grating sensitivity enhancement structure is briefly described below.

[0063] At normal temperature and pressure, the temperature sensitivity coefficient of the grating 10 in a normal state can be kt=10pm / ℃, the strain coefficient of the grating 10 ε=1.2pm / με, and the temperature thermal expansion coefficient of copper α=18×10 -6 . That is to say, for 1 meter of copper, the linear expansion is about 18μm for every 1°C increase in temperature. In this way, the first copper film 104a and the second copper film 104b will produce about 18με (micro strain) for every 1°C increase in temperature. At the same time, for every 1°C increase in temperature of the first copper film 104a and the second copper film 104b, the change in the wavelength of the grating 10 caused by the axial strain of the optical fiber 1 can be 21.6pm. The strain generated by the expansion of the first copper film 104a and the second copper film 104b is superimposed on the temperature effect of the grating 10, so that the temperature sensitivity coefficient of the superimposed optical fiber sensor is 31.6pm / °C, which can greatly improve the sensitivity of the optical fiber sensor.

[0064] At the same time, the D-type grating 10 structure causes uneven force on both sides of the grating 10, and the first copper film 104a and the second copper film 104b expand and deform during the hydrogen absorption process of the Pt / WO3 film 105, thereby causing the deformation of the grating 10 to enhance the strain effect. Considering the bending effect of the D-type grating 10, the wavelength shift caused by the bending can be 10pm for every 1°C increase. Then, when superimposed with the strain effect of the first copper film 104a and the second copper film 104b, the temperature sensitivity coefficient of the optical fiber sensor is 31.6pm / °C+10pm / °C=41.6pm / °C. The superposition of these three effects ultimately increases the sensitivity of the optical fiber sensor to hydrogen to 41.6pm / °C, which is 4 times higher than the temperature sensitivity of the optical fiber sensor using only the Pt / WO3 film 105.

[0065] The method for preparing the grating sensitivity enhancement structure provided in the embodiment of the present application is to prepare a groove 103 on the annular surface 102 of the grating 10 on the side that has not been subjected to the side polishing process after the grating 10 is processed by the side polishing process, so that the processed grating 10 has two structures, the D-type and the groove 103, and prepare a metal film 104 and a Pt / WO3 film 105 on the groove 103. The Pt / WO3 film 105, as a hydrogen-sensitive material, absorbs hydrogen and releases heat, and the grating 10 responds to the thermal effect. While achieving the effect of detecting the hydrogen concentration, it can also effectively enhance the sensitivity of the optical fiber sensor, ensuring the rapid and accurate measurement of the hydrogen concentration.

[0066] Corresponding to the above-mentioned embodiment of the method for preparing a grating sensitivity enhancement structure, the present application also provides an embodiment of a grating sensitivity enhancement structure, and the grating sensitivity enhancement structure is prepared by the above-mentioned method for preparing a grating sensitivity enhancement structure.

[0067] Combination Figure 1 , Figure 7 and Figure 8The grating sensitivity enhancement structure includes a D-type grating 10, a groove 103, a metal film 104 and a Pt / WO3 film 105.

[0068] Specifically, a D-type grating 10 is arranged on an optical fiber 1; wherein the cross-sectional shape of the D-type grating 10 is D-shaped, and the D-type grating 10 is obtained by removing a cladding 30 of a preset length and a preset height from the optical fiber 1 through a side-polishing process, and the D-type grating 10 includes a side-polished surface 101 and an annular surface 102, and the side-polished surface 101 is formed by side-polishing.

[0069] In other words, the D-type grating 10 can be prepared by step S100 in the above-mentioned method for preparing a grating sensitivity enhancement structure.

[0070] A plurality of grooves 103 are disposed on the annular surface 102 ; wherein the plurality of grooves 103 are arranged in sequence along the length direction of the optical fiber 1 .

[0071] In other words, the groove 103 can be prepared by step S200 in the above-mentioned method for preparing the grating sensitivity enhancement structure. The groove 103 can be a spiral groove, or a straight groove.

[0072] The metal film 104 covers the annular surface 102 ; wherein the metal film 104 covers the plurality of grooves 103 .

[0073] In other words, the metal film 104 can be prepared by step S300 in the above-mentioned method for preparing the grating sensitivity enhancement structure.

[0074] In some feasible implementations, the metal film 104 may be a copper film, and the metal film 104 may include a first copper film 104a and a second copper film 104b, and the first copper film 104a and the second copper film 104b may be prepared by step S301 and step S302 in the above-mentioned embodiment of the method for preparing the grating sensitivity enhancement structure, respectively.

[0075] The thickness of the first copper film 104a is smaller than that of the second copper film 104b. The thickness of the first copper film 104a may be 80-120 nm; the thickness of the second copper film 104b may be 10-50 μm.

[0076] In a specific implementation, the thickness of the first copper film 104 a may be 105 nm, and the thickness of the second copper film 104 b may be 25 μm.

[0077] The Pt / WO3 film 105 covers the metal film 104 and the side polished surface 101 .

[0078] In other words, the Pt / WO3 film 105 can be prepared by step S400 in the above-mentioned method for preparing a grating sensitivity enhancement structure. 10 H 14 O4Pt and WO3 are prepared. The thickness of the Pt / WO3 film 105 can be 2-30 μm.

[0079] In a specific implementation, the thickness of the Pt / WO 3 film 105 may be 5.5 μm.

[0080] It is worth noting that Figure 8 The number of the grooves 103 shown is 6. In other specific implementations, the number of the grooves 103 may be 8, 10, or a greater or lesser number.

[0081] The grating sensitivity enhancement structure provided in the embodiment of the present application uses Pt / WO3 film 105 as a hydrogen sensitive material. When the hydrogen concentration changes, the Pt / WO3 film 105 absorbs hydrogen and releases heat, causing the temperature of the grating 10 to rise. The metal film 104 expands and deforms due to the thermal effect, pulling the grating 10 to generate strain, thereby increasing the response of the optical fiber sensor to the change in hydrogen concentration, thereby increasing the sensitivity of the optical fiber sensor. At the same time, the grating 10 is side-cast to form a D-shaped structure, and the two sides of the grating 10 are subjected to uneven force, causing the grating 10 to bend, enhancing the strain effect, and further enhancing the sensitivity of the optical fiber sensor.

[0082] Corresponding to the above-mentioned grating sensitivity enhancement structure embodiment, the present application also provides an embodiment of an optical fiber sensor, which includes the grating sensitivity enhancement structure provided in the above-mentioned embodiment. Therefore, the optical fiber sensor provided in the embodiment of the present application has the advantages of high sensitivity, strong stability and long-term reliability when detecting hydrogen. Moreover, the optical fiber sensor has a simple structure, high measurement accuracy, and strong anti-electromagnetic interference ability, and can be widely used in industrial hydrogen leak detection, hydrogen energy storage monitoring, scientific research experiments and other fields.

[0083] It should be noted that those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variation, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application.

[0084] It should be understood that the present application is not limited to the precise construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof, the true scope being indicated by the present application.

Claims

1. A method for preparing a grating sensitivity enhancement structure, characterized in that: include: A side polishing process is adopted to remove a cladding of a preset length and a preset height from the optical fiber; wherein the optical fiber after removal comprises a side polishing surface and an annular surface, the side polishing surface is formed by side polishing, the side polishing surface covers the grating of the optical fiber, the preset length is greater than the length of the entire grating, and the cross-sectional shape of the grating after the cladding is removed is a D-type; A plurality of grooves are etched on the annular surface; wherein the plurality of grooves are arranged in sequence along the length direction of the optical fiber; A metal film is plated on the annular surface; wherein the metal film covers a plurality of the grooves; A Pt / WO3 film is prepared on the metal film and the side polished surface to obtain a grating sensitivity enhancement structure.

2. The method for preparing a grating sensitivity enhancement structure according to claim 1, characterized in that: The groove is a spiral groove.

3. The method for preparing a grating sensitivity enhancement structure according to claim 1, characterized in that: The groove is a straight groove.

4. The method for preparing a grating sensitivity enhancement structure according to claim 1, characterized in that: The depth of the groove is 3-10 μm.

5. The method for preparing a grating sensitivity enhancement structure according to claim 1, characterized in that: The preset height is 1 / 5 to 1 / 3 of the diameter of the optical fiber.

6. The method for preparing a grating sensitivity enhancement structure according to claim 1, characterized in that: The metal film is a copper film; the metal film is plated on the annular surface, including: Using a magnetron sputtering method, coating a first copper film on the annular surface; The second copper film is plated on the first copper film by electroplating; wherein the thickness of the first copper film is smaller than the thickness of the second copper film.

7. The method for preparing a grating sensitivity enhancement structure according to claim 6, characterized in that: The thickness of the first copper film is 80-120 nm, and the thickness of the second copper film is 10-50 μm.

8. The method for preparing a grating sensitivity enhancement structure according to claim 1, characterized in that: The Pt / WO3 film is prepared by a sol-gel method through C 10 H 14 O4Pt and WO3 are prepared, and the thickness of the Pt / WO3 film is 2-30μm.

9. A grating sensitivity enhancement structure, characterized in that: The grating sensitivity enhancement structure is prepared by the preparation method of the grating sensitivity enhancement structure according to any one of claims 1 to 8, wherein the grating sensitivity enhancement structure comprises: A D-type grating is arranged on an optical fiber; wherein the cross-sectional shape of the D-type grating is D-shaped, the D-type grating is obtained by removing a cladding of a preset length and a preset height from the optical fiber through a side-polishing process, the D-type grating comprises a side-polished surface and an annular surface, and the side-polished surface is formed by side-polishing; A plurality of grooves are arranged on the annular surface; wherein the plurality of grooves are arranged in sequence along the length direction of the optical fiber; A metal film, covering the annular surface; wherein the metal film covers a plurality of the grooves; A Pt / WO3 film covers the metal film and the side polished surface.

10. An optical fiber sensor, characterized in that: Comprising the grating sensitivity enhancement structure as described in claim 9.

Images