Gold-plated fiber grating and preparation method thereof

Abstract

The invention provides a gold-plated fiber bragg grating and a preparation method thereof, the gold-plated fiber bragg grating comprises an optical fiber main body part and a grating part connected with the optical fiber main body part, and the grating part comprises a grating structure, a nickel-plated metal layer and a gold-plated metal layer which are sequentially arranged from inside to outside in the radial direction. According to the invention, the nickel-plated metal layer is formed on the grating structure, so that the subsequently formed gold-plated metal layer is not easy to fall off on the grating structure, the gold-plated metal layer can improve the energy transfer effect and the energy transfer stability of the optical fiber, and the tuning wavelength of the gold-plated fiber grating and the temperature change are in a good linear relationship; meanwhile, the temperature sensing range of the gold-plated fiber grating is well improved by the gold-plated metal layer.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber grating, and in particular to a gold-plated optical fiber grating and a preparation method thereof. Background Art

[0002] Fiber Bragg grating is a kind of optical passive device made by the nonlinear absorption effect of germanium-doped optical fiber. It has been widely used in the field of optical fiber communication and sensing because of its advantages such as small size, immunity to electromagnetic interference, intrinsic safety, and ability to be packaged with other materials. In addition, its wavelength changes are sensitive to changes in external temperature and can be restored and reproduced. However, since fiber Bragg grating belongs to wavelength modulation type optical fiber sensor, the current fiber Bragg grating temperature sensor has poor stability, low accuracy, and small temperature test range in practical applications. There is no improvement for this defect.

[0003] Therefore, it is urgent to develop a gold-plated fiber grating and a preparation method thereof to solve the above technical problems. Summary of the invention

[0004] The purpose of the present invention is to provide a gold-plated fiber Bragg grating and a preparation method thereof, so as to solve the technical problems of poor stability, low precision and small temperature test range of the current fiber Bragg grating.

[0005] In order to solve the above technical problems, the present invention first provides a gold-plated fiber Bragg grating, comprising a fiber main body and a grating part connected to the fiber main body; The grating part includes a grating structure, a nickel-plated metal layer and a gold-plated metal layer which are sequentially arranged from the inside to the outside along the radial direction.

[0006] Preferably, the optical fiber body comprises a core layer, a core cladding layer, a jacket layer and a protective layer which are sequentially arranged from the inside to the outside along the radial direction.

[0007] Preferably, the grating structure comprises a grating body and a roughening layer wrapped around the outer surface of the grating body, and the grating body is formed by recording the core layer through an ultraviolet exposure process.

[0008] Preferably, the length of the grating portion is 3-5 cm, and the thickness of the grating portion is 20-40 μm.

[0009] Preferably, the thickness of the nickel-plated metal layer is 2-5 μm, and the thickness of the gold-plated metal layer is 6-10 μm.

[0010] Preferably, the reflectivity of the grating body is greater than 90%, the side mode suppression ratio is greater than 12 dB, and the 3 dB bandwidth is less than 0.22 nm.

[0011] Accordingly, the present invention also provides a method for preparing the gold-plated fiber grating as described above, the method comprising: S10, providing an optical fiber, wherein the optical fiber includes an optical fiber main body having a grating region; S20, forming a grating structure in the grating region; S30, forming a nickel-plated metal layer on the surface of the grating structure; S40, forming a gold-plated metal layer on the surface of the nickel-plated metal layer.

[0012] Preferably, before performing step S10, the method further includes: placing the optical fiber into a hydrogen-carrying device for sensitization treatment.

[0013] Preferably, step S20 specifically includes: S201, chemically stripping the main body of the optical fiber located in the grating region so that the portion of the optical fiber corresponding to the grating region has only a core layer; S202, performing patterning on the core layer located in the grating region to obtain a grating body; S203, performing a roughening process on the grating body to obtain a roughening layer, wherein the grating body and the roughening layer constitute a grating structure.

[0014] Preferably, in step S30: the nickel-plated metal layer is plated on the surface of the grating structure by a chemical plating method; in step S40: the gold-plated metal layer is plated on the surface of the nickel-plated metal layer by an electroplating method.

[0015] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a gold-plated fiber Bragg grating and a preparation method thereof, wherein the gold-plated fiber Bragg grating comprises a fiber main body and a grating part connected to the fiber main body, wherein the grating part comprises a grating structure, a nickel-plated metal layer and a gold-plated metal layer arranged in sequence from the inside to the outside along the radial direction. The present invention forms a nickel-plated metal layer on the grating structure so that the subsequently formed gold-plated metal layer is not easy to fall off on the grating structure, so that the gold-plated metal layer can improve the energy transfer effect and energy transfer stability of the optical fiber, thereby making the tuning wavelength of the gold-plated fiber Bragg grating have a good linear relationship with the temperature change; at the same time, the gold-plated metal layer greatly improves the temperature sensing range of the gold-plated fiber Bragg grating. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of the main part of the optical fiber in the gold-plated optical fiber Bragg grating provided in an embodiment of the present invention; Figure 2 A flow chart of a method for preparing a gold-plated fiber Bragg grating according to an embodiment of the present invention; Figure 3 The wavelength linearity diagram of the gold-plated fiber Bragg grating provided in Example 1 of the present invention; Figure 4 A comparison chart of the grating temperature coefficients of the gold-plated fiber Bragg grating provided in Example 1 of the present invention and the fiber Bragg gratings provided in Comparative Examples 1 and 2; Figure 5 A comparison chart of the grating breaking force of the gold-plated fiber Bragg grating provided in Example 1 of the present invention and the fiber Bragg grating provided in Comparative Examples 1 and 2; In the figure: 10 - core layer; 20 - core cladding layer; 30 - outer jacket layer; 40 - protective layer. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In view of the deficiencies of the prior art, the present invention provides a metallized fiber Bragg grating and a method for manufacturing the same, which solves the problems of poor stability, low accuracy and small temperature test range of the current fiber Bragg grating in practical applications.

[0019] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention first provides a gold-plated fiber grating, comprising a fiber main body and a grating part connected to the fiber main body; The grating part includes a grating structure, a nickel-plated metal layer and a gold-plated metal layer which are sequentially arranged from the inside to the outside along the radial direction.

[0020] See also Figure 1 , Figure 1 A schematic structural diagram of the main body of an optical fiber in a gold-plated optical fiber Bragg grating provided in an embodiment of the present invention; wherein the main body of the optical fiber comprises a core layer 10, a core cladding layer 20, a jacket layer 30 and a protective layer 40 arranged in sequence from the inside to the outside along the radial direction.

[0021] Specifically, the core layer 10 is the most important part of the optical fiber and is responsible for transmitting optical signals; it is made of high-purity glass or plastic material and has a high refractive index.

[0022] Specifically, the core cladding layer 20 is located outside the core layer 10, and its main function is to confine the optical signal in the core layer 10 to prevent the optical signal from leaking into the external environment. The refractive index of the core cladding layer 20 is lower than that of the core layer 10. When the optical signal propagates in the core layer 10, due to the difference in refractive index, the optical signal will be totally reflected at the interface between the core layer 10 and the core cladding layer 20, thereby being confined in the core layer 10.

[0023] Specifically, the outer jacket layer 30 is located outside the core cladding layer 20, and its main function is to protect the internal structure of the optical fiber from the influence of the external environment. The outer jacket layer 30 is usually made of plastic or other materials, and has high mechanical strength and corrosion resistance.

[0024] Specifically, the protective layer 40 is located outside the outer jacket layer 30, and its main function is to further protect the optical fiber from the external environment and improve the mechanical strength and corrosion resistance of the optical fiber. The protective layer 40 is usually composed of one or more layers of material and has good adhesion and wear resistance.

[0025] In the embodiment of the present invention, the grating structure includes a grating body and a roughening layer wrapped around the outer surface of the grating body. The grating body is formed by recording the core layer 10 through an ultraviolet exposure process.

[0026] Specifically, the grating body periodically changes the refractive index of light. When the light axis passes through the grating structure, it will continuously reflect, diffract and interfere between the stripes of the grating structure to form a specific waveform wavelength. When external physical quantities (such as temperature, etc.) act on this section of the grating structure, the texture period of the grating structure will change, which will cause the resonant wavelength of the grating structure to change. By measuring the change in this wavelength, information about the measured physical quantity can be obtained.

[0027] Specifically, the roughening layer can increase the microscopic roughness and contact area of ​​the surface of the grating body, protect the grating body from the influence of the external environment, and improve the mechanical strength and corrosion resistance of the grating body.

[0028] In an embodiment of the present invention, the length of the grating portion is 3 to 5 cm, and the thickness of the grating portion is 20 to 40 μm; wherein, the increase in the length of the grating portion can improve the sensitivity of the fiber Bragg grating sensor. A longer grating length means that more grating periods are involved in sensing, thereby producing a more obvious response to changes in external physical quantities. For example, in temperature sensing, a longer fiber Bragg grating can more accurately detect slight changes in temperature. However, increased sensitivity may also bring some problems, such as increased sensitivity to noise. Therefore, when designing a fiber Bragg grating sensor, it is necessary to comprehensively consider the balance between sensitivity and noise performance.

[0029] Furthermore, the reflectivity of the grating body is greater than 90%, the side mode suppression ratio is greater than 12dB, and the 3dB bandwidth is less than 0.22nm; among them, the fiber Bragg grating with a reflectivity greater than 90% can improve the sensitivity and stability of the sensor and reduce the impact of external interference on the measurement results; the side mode suppression ratio refers to the power ratio of the main mode to the side mode. A high side mode suppression ratio means that the power of the main mode is much greater than the power of the side mode, thereby reducing the interference of the side mode on the main mode; the 3dB bandwidth refers to the wavelength range corresponding to the reflection power in the fiber Bragg grating reflection spectrum when it drops to half of the maximum value. The narrow 3dB bandwidth means that the fiber Bragg grating can filter light of a specific wavelength more accurately.

[0030] In the embodiment of the present invention, the thickness of the nickel-plated metal layer is 2-5 μm, and the thickness of the gold-plated metal layer is 6-10 μm.

[0031] See also Figure 2 , Figure 2 A flow chart of a method for preparing a gold-plated fiber Bragg grating provided in an embodiment of the present invention; wherein the method comprises: S10, providing an optical fiber, wherein the optical fiber comprises an optical fiber main body having a grating region.

[0032] Specifically, step S10 also includes: First, an optical fiber is provided, wherein the optical fiber comprises an optical fiber main body having a grating region; wherein the optical fiber is preferably a G.652 single-mode optical fiber.

[0033] Afterwards, the optical fiber is placed in a hydrogen-carrying device for sensitization treatment; preferably, in step S10, the hydrogen-carrying environment is maintained at 10 MPa for a period of 7 to 14 days.

[0034] Specifically, sensitized optical fibers can more easily produce high-quality fiber Bragg gratings. In the process of making fiber Bragg gratings, it is usually necessary to use ultraviolet light to expose the optical fiber to change the refractive index of the optical fiber. The optical fiber after sensitization has an enhanced ability to absorb ultraviolet light, making the exposure process easier, so that a more uniform and stable fiber Bragg grating can be produced.

[0035] Specifically, the higher the hydrogen pressure, the faster the diffusion of hydrogen in the optical fiber and the better the sensitization effect. However, too high a hydrogen pressure may cause mechanical damage to the optical fiber, so it is necessary to select an appropriate hydrogen pressure according to the type of optical fiber and application requirements.

[0036] S20, forming a grating structure in the grating region.

[0037] Specifically, step S20 also includes: S201, chemically stripping the main part of the optical fiber located in the grating region, so that the portion of the optical fiber corresponding to the grating region only has the core layer 10, and the specific process is as follows: First, the optical fiber is soaked in acetone for about 25 minutes, and then the core cladding layer 20, the jacket layer 30 and the protective layer 40 are removed. During the soaking process, the main part of the optical fiber outside the grating area needs to be protected; Preferably, the length of the core cladding layer 20, the outer jacket layer 30 and the protective layer 40 removed is 3-5 cm, and a 304 stainless steel fixture is used for protection during the protection process, while minimizing the volatilization of acetone.

[0038] Secondly, remove the chemical substances on the surface of the bare fiber in the grating area to prepare for the next step of grating writing; Preferably, dust-free paper and anhydrous ethanol are used for cleaning.

[0039] S202, patterning the core layer 10 located in the grating region to obtain a grating body, the specific process is as follows: First, the grating body is written on the core layer 10 located in the grating area by ultraviolet exposure; After that, the engraved grating body is left at room temperature for 24 hours. During the engraving process of the grating body, due to factors such as laser irradiation and physical deformation, certain stress will be generated inside the optical fiber. These stresses may affect the optical performance and stability of the grating body. By leaving it at room temperature for 24 hours, the stress inside the optical fiber can be gradually released, making the structure of the grating body more stable.

[0040] S203, performing a coarsening process on the grating body to obtain a coarsening layer, wherein the grating body and the coarsening layer constitute a grating structure, and the specific process is as follows: The surface of the grating body is roughened by a roughening agent to obtain a roughening layer, so as to increase the microscopic roughness and contact area of ​​the surface of the grating body.

[0041] Preferably, the roughening agent is hydrofluoric acid, fluorosilicic acid, and purified water in a ratio of 1:1:3, and the roughening time is 8 minutes.

[0042] S30, forming a nickel-plated metal layer on the surface of the grating structure.

[0043] Specifically, step S30 also includes: A nickel-plated metal layer is formed on the surface of the grating structure by a chemical plating method.

[0044] S40, forming a gold-plated metal layer on the surface of the nickel-plated metal layer.

[0045] Specifically, step S40 also includes: First, a gold-plated metal layer is formed on the surface of the nickel-plated metal layer by an electroplating method, and the thickness of the grating portion finally obtained is 20 to 40 microns, preferably 30 microns; Afterwards, the entire gold-plated fiber Bragg grating is effectively protected through structural packaging.

[0046] The gold-plated fiber grating and the preparation method thereof provided by the present invention are further described in conjunction with specific embodiments.

[0047] Embodiment 1: This embodiment 1 first provides a gold-plated fiber Bragg grating, comprising a fiber main body and a grating part connected to the fiber main body, the grating part comprising a grating structure, a nickel-plated metal layer and a gold-plated metal layer arranged in sequence from the inside to the outside along the radial direction, the grating structure comprising a grating body and a roughening layer wrapped around the outer surface of the grating body, and the grating body is formed by recording the fiber core layer 10 through an ultraviolet exposure process; Among them, the optical fiber body is G.652 optical fiber, the length of the grating part is 3cm, and the thickness of the grating part is 30μm; the reflectivity of the grating body is greater than 90%, the side mode suppression ratio is greater than 12dB, and the 3dB bandwidth is less than 0.22nm; the thickness of the nickel-plated metal layer is 5μm, and the thickness of the gold-plated metal layer is 10μm.

[0048] This embodiment 1 also provides a method for preparing a gold-plated fiber Bragg grating, and the specific process is as follows: Step (1), placing the G.652 optical fiber in a hydrogen-carrying device for sensitization treatment, maintaining the hydrogen-carrying environment at 10 MPa, and controlling the time to be 7 to 14 days; Step (2), before the soaking process, the optical fiber outside the area where the grating is to be engraved is protected, and after the main part of the optical fiber in the grating area is soaked in acetone for about 25 minutes, the length of the cladding, the jacket layer 30 and the protective layer 40 is removed to be 5 cm, and at the same time, a 304 stainless steel fixture is used to protect the main part of the optical fiber outside the grating area, while minimizing the volatilization of acetone; Step (3), using dust-free paper and anhydrous ethanol for cleaning to remove the surface chemical substances of the fiber core layer 10 in the grating area, in preparation for the next step of grating writing; Step (4), writing a grating body into the core layer 10 in the grating region by ultraviolet exposure, wherein the reflectivity of the grating body is greater than 90%, the side mode suppression ratio is greater than 12 dB, and the 3 dB bandwidth is less than 0.22 nm; Step (5), leaving the written fiber Bragg grating to stand at room temperature for 24 hours; Step (6), roughening the surface of the grating body to increase the surface micro-roughness and contact area of ​​the grating body to obtain a roughened layer, and finally using an ultrasonic cleaning machine and pure water for cleaning; wherein the roughening time is 8 minutes, and the selected materials are hydrofluoric acid, fluorosilicic acid, and pure water in a ratio of 1:1:3; Step (7), performing metallization treatment on the surface of the roughened layer, using nickel sulfate for chemical nickel plating, sodium hypophosphite as a reducing agent, and obtaining a nickel-plated metal layer as a gold plating basis after solidification on the surface of the roughened layer, wherein the thickness of the nickel-plated metal layer is 5 μm; Step (8), electroplating the nickel-plated metal layer with gold, the gold plating temperature is set to 200° C., the thickness of the gold-plated metal layer is 10 μm, and the thickness of the grating portion after all metallization is completed is 30 μm; Step (9), effectively protecting the entire gold-plated fiber Bragg grating through structural packaging.

[0049] Comparative Example 1: Comparative Example 1 provides an acrylate-coated optical fiber Bragg grating, whose optical fiber main body is a G.652 optical fiber, the length of the grating region is 5 μm, the reflectivity is greater than 90%, the side mode suppression ratio is greater than 12 dB, the 3dB bandwidth is less than 0.22 nm, and the grating region is coated with an acrylate material layer, and the thickness of the acrylate material layer is 15 μm.

[0050] Comparative Example 2: Comparative Example 2 provides a nickel-plated fiber grating, whose fiber main body is G.652 fiber, the length of the grating area is 5μm, the reflectivity is greater than 90%, the side mode suppression ratio is greater than 12dB, the 3dB bandwidth is less than 0.22nm, and the grating area is provided with a nickel-plated metal layer with a thickness of 15μm.

[0051] See also Figure 3 , Figure 3 The wavelength linearity diagram of the gold-plated fiber Bragg grating provided in Example 1 of the present invention; wherein the wavelength linearity equation of the gold-plated fiber Bragg grating provided in Example 1 of the present invention is: y=17.96x+2E06, R 2 =0.99<1; Among them, x is the temperature value, y is the wavelength value, R 2 It is very close to 1, indicating that the linear model fits the data very well, that is, there is a strong linear relationship between the temperature value x and the wavelength value y.

[0052] See also Figure 4 , Figure 4 The grating temperature coefficient comparison diagram of the gold-plated fiber Bragg grating provided in Example 1 of the present invention and the fiber Bragg grating provided in Comparative Examples 1-2 is shown; wherein, five samples of the gold-plated fiber Bragg grating provided in Example 1 of the present invention, five samples of the acrylate-coated fiber Bragg grating provided in Comparative Example 1, and five samples of the nickel-plated fiber Bragg grating provided in Comparative Example 2 are selected respectively, and optical signals are transmitted to the above 15 samples respectively. During the transmission, the linear relationship between temperature and wavelength and the operable temperature range are detected respectively. After experimental comparison, it can be known that the temperature sensitivity of the acrylate-coated fiber Bragg grating provided in Comparative Example 1 is 10.4 pm / °C on average, the temperature sensitivity of the nickel-plated fiber Bragg grating provided in Comparative Example 2 is 11.5 pm / °C on average, and the temperature sensitivity of the gold-plated fiber Bragg grating provided in Example 1 of the present invention is 17.8 pm / °C on average; the above results indicate that the temperature sensitivity of the gold-plated fiber Bragg grating provided in Example 1 of the present invention is better than that of the fiber Bragg gratings provided in Comparative Examples 1-2.

[0053] See also Figure 5 , Figure 5The present invention provides a comparison chart of the grating breaking force of the gold-plated fiber Bragg grating provided in Example 1 of the present invention and the fiber Bragg grating provided in Comparative Examples 1-2; wherein, five samples of the gold-plated fiber Bragg grating provided in Example 1 of the present invention, five samples of the acrylate-coated fiber Bragg grating provided in Comparative Example 1, and five samples of the nickel-plated fiber Bragg grating provided in Comparative Example 2 are respectively selected, and the above 15 samples are respectively subjected to tensile tests. After experimental comparison, it can be known that the grating breaking force of the gold-plated fiber Bragg grating provided in Example 1 of the present invention is greater than the grating breaking force of the nickel-plated fiber Bragg grating provided in Comparative Example 2, and the grating breaking force of the nickel-plated fiber Bragg grating provided in Comparative Example 2 is greater than the grating breaking force of the acrylate-coated fiber Bragg grating provided in Comparative Example 1; the above results indicate that the grating breaking force of the gold-plated fiber Bragg grating provided in Example 1 of the present invention is better than the grating breaking force of the fiber Bragg grating provided in Comparative Examples 1-2.

[0054] Compared with the prior art, the present invention has the following beneficial effects: 1. The gold-plated fiber Bragg grating and its manufacturing method provided in the embodiment of the present invention can optimize the energy transfer effect of the optical fiber by metallizing the grating structure, and the transfer stability is high, so that the manufactured tuning wavelength has a good linear relationship with the temperature change, and the gold-plated metal layer greatly improves the temperature range of the fiber Bragg grating.

[0055] 2. The manufacturing process of the gold-plated fiber Bragg grating provided in the embodiment of the present invention is simple. Through the gold plating process and the packaging process, the fiber Bragg grating is well protected. At the same time, the temperature detection range of the fiber Bragg grating is greatly improved, making it an optimized solution for monitoring in high temperature environments.

[0056] In summary, in practical applications, the gold-plated fiber Bragg grating manufactured by the present invention can optimize the temperature transfer effect and grating area strength of the fiber Bragg grating compared with the acrylate-coated fiber Bragg grating and the nickel-plated fiber Bragg grating, and the temperature transfer stability is high, so that the trend of wavelength change with temperature is not easily distorted, while ensuring linearity, thereby optimizing the temperature performance of the fiber Bragg grating, having a simple manufacturing process, and providing a good protection for the fiber Bragg grating, making it an ideal solution for temperature testing at higher temperatures.

[0057] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A gold-plated fiber Bragg grating, characterized in that: It includes an optical fiber main body and a grating part connected to the optical fiber main body; The grating portion includes a grating structure, a nickel-plated metal layer and a gold-plated metal layer which are sequentially arranged from the inside to the outside along the radial direction.

2. The gold-plated fiber Bragg grating according to claim 1, characterized in that: The optical fiber main body comprises a core layer, a core cladding layer, a jacket layer and a protective layer which are arranged in sequence from the inside to the outside along the radial direction.

3. The gold-plated fiber Bragg grating according to claim 2, characterized in that: The grating structure comprises a grating body and a roughening layer wrapped around the outer surface of the grating body. The grating body is formed by recording the core layer through an ultraviolet exposure process.

4. The gold-plated fiber Bragg grating according to claim 1, characterized in that: The length of the grating portion is 3-5 cm, and the thickness of the grating portion is 20-40 μm.

5. The gold-plated fiber Bragg grating according to claim 3, characterized in that: The thickness of the nickel-plated metal layer is 2-5 μm, and the thickness of the gold-plated metal layer is 6-10 μm.

6. The gold-plated fiber Bragg grating according to claim 1, characterized in that: The reflectivity of the grating body is greater than 90%, the side mode suppression ratio is greater than 12dB, and the 3dB bandwidth is less than 0.22nm.

7. A method for preparing a gold-plated fiber Bragg grating according to any one of claims 1 to 6, characterized in that: The method comprises: S10, providing an optical fiber, wherein the optical fiber comprises the optical fiber main body having the grating region; S20, forming the grating structure in the grating region; S30, forming the nickel-plated metal layer on the surface of the grating structure; S40, forming the gold-plated metal layer on the surface of the nickel-plated metal layer.

8. The method for preparing a gold-plated fiber Bragg grating according to claim 7, characterized in that: Before performing the step S10, the method further includes: placing the optical fiber in a hydrogen-carrying device for sensitization treatment.

9. The method for preparing a gold-plated fiber Bragg grating according to claim 7, characterized in that: The step S20 specifically includes: S201, performing chemical stripping treatment on the main body of the optical fiber located in the grating region, so that the portion of the optical fiber corresponding to the grating region has only a core layer; S202, performing patterning on the core layer located in the grating region to obtain a grating body; S203, performing a roughening process on the grating body to obtain a roughening layer, wherein the grating body and the roughening layer constitute the grating structure.

10. The method for preparing a gold-plated fiber Bragg grating according to claim 7, characterized in that: In the step S30: the nickel-plated metal layer is plated on the surface of the grating structure by a chemical plating method; in the step S40: the gold-plated metal layer is plated on the surface of the nickel-plated metal layer by an electroplating method.

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