Fiber Bragg Grating Hot Wire Wind Speed ​​Sensor Based on Multi-core Fiber and Its Measuring Device

Abstract

The present invention discloses a fiber grating hot-wire wind speed sensor based on a multi-core optical fiber and a measuring device thereof, and relates to the technical field of optical fiber sensors. The wind speed sensor comprises a multi-core optical fiber, a long-period optical fiber grating, a fiber Bragg grating and a metal film; the long-period optical fiber grating and the fiber Bragg grating are arranged in different cores of the multi-core optical fiber; the metal film is coated on the circumference of the multi-core optical fiber. The present invention arranges the long-period optical fiber grating and the fiber Bragg grating in different cores of the multi-core optical fiber, so that the signal light and the pump light are transmitted separately, and the interference of the long-period optical fiber grating on the signal light is avoided, and the signal light loss is small; the metal film coated on the circumference of the multi-core optical fiber is used to sense temperature changes, and cause the temperature change of the fiber Bragg grating, thereby causing the wavelength of the fiber Bragg grating to change when reflecting the signal light, and obtain wind speed information; the present invention has a simple structure, a small volume, and a high sensitivity, and can measure accurate wind speed.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensors, and more specifically, to an optical fiber grating hot wire wind speed sensor based on a multi-core optical fiber and a measuring device thereof. Background Art

[0002] Wind is a natural phenomenon that is ubiquitous. The monitoring of wind speed plays a very important role in many fields such as industrial and agricultural production, transportation, aerospace, and the automotive industry. Wind speed measurement sensors are mainly divided into mechanical wind speed sensors and differential pressure wind speed sensors. Mechanical wind speed sensors include stress micro-bend fiber optic wind speed sensors and three-cup anemometers; differential pressure wind speed sensors include differential pressure fiber optic Fabry-Perot wind speed sensors and Pitot tube anemometers. There are also vortex gas flow sensors, ultrasonic wind speed sensors, thermal gas flow sensors, and particle imaging flow sensors. These sensors are susceptible to electromagnetic interference, high cost, and large size. In recent years, fiber optic anemometers have become the trend of wind speed measurement research due to their high sensitivity, ease of use, anti-electromagnetic interference, and wide measurement range. The combination of fiber grating technology and wind speed sensing technology has broad research prospects and research significance.

[0003] The prior art discloses an optical fiber flow sensor based on doped fiber Bragg gratings, including a doped optical fiber with fiber Bragg grating A engraved, a single-mode optical fiber with fiber Bragg grating B engraved, a wavelength demodulation module, a wavelength division multiplexer and a pump laser; the doped optical fiber and the single-mode optical fiber are core-welded to serve as the sensing unit of the sensor, and the wavelength division multiplexer connects the sensing unit with the pump laser and the wavelength demodulation module. The application fuses two sections of optical fiber to the core, which has defects such as core diameter mismatch, poor fiber concentricity, and fiber end face contamination, resulting in large optical fiber transmission loss; and the signal light and the pump light are transmitted in the same optical fiber, and the fiber Bragg grating will affect the signal light, resulting in inaccurate flow data finally measured. Summary of the invention

[0004] In order to overcome the defect in the above-mentioned existing wind speed sensor that the signal light and the pump light affect the signal light when they are transmitted together in a single-mode optical fiber, resulting in inaccurate measurement results, the present invention provides a fiber grating hot wire wind speed sensor based on a multi-core optical fiber and a measuring device thereof, which can separate the signal light and the pump light for transmission, avoid affecting the signal light, and ensure accurate measurement results.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] The present invention provides a fiber Bragg grating hot-wire wind speed sensor based on a multi-core optical fiber, wherein the wind speed sensor comprises a multi-core optical fiber, a long-period optical fiber grating, a fiber Bragg grating and a metal film;

[0007] The long-period fiber grating and the fiber Bragg grating are arranged in different cores of the multi-core optical fiber; and the metal film is coated on the circumference of the multi-core optical fiber.

[0008] The present invention places the long-period fiber grating and the fiber Bragg grating in different cores of a multi-core optical fiber, respectively, so that the signal light and the pump light are transmitted separately in the multi-core optical fiber, avoiding the influence of the long-period fiber grating on the signal light, and the final measurement result is more accurate.

[0009] The principle of the fiber Bragg grating hot wire wind speed sensor is that the pump light is coupled to the fiber cladding through the long-period fiber Bragg grating. The metal film coated on the multi-core optical fiber absorbs the pump light to generate heat, causing the temperature of the fiber Bragg grating to rise and the reflected wavelength to redshift. When the external wind speed is not zero, the temperature of the metal film decreases, and then the temperature of the fiber Bragg grating also decreases, and the reflected wavelength blueshifts. The amount of wavelength blueshift has a fixed relationship with the wind speed, thereby measuring the wind speed.

[0010] Preferably, the length of the long-period fiber grating is greater than the length of the fiber Bragg grating.

[0011] Preferably, the projection of the long-period fiber grating on the axis of the multi-core optical fiber does not overlap with the projection of the fiber Bragg grating on the axis of the multi-core optical fiber.

[0012] Preferably, the distance d between the projection of the long-period fiber grating on the axis of the multi-core optical fiber and the projection of the fiber Bragg grating on the axis of the multi-core optical fiber is in the range of 3-5 mm.

[0013] Preferably, the projection of the metal film on the axis of the multi-core optical fiber does not overlap with the projection of the long-period fiber grating on the axis of the multi-core optical fiber, so as to avoid the influence of the temperature change of the metal film on the transmission spectrum of the long-period fiber grating.

[0014] Preferably, the projection of the metal film on the axis of the multi-core optical fiber coincides with the projection of the fiber Bragg grating on the axis of the multi-core optical fiber.

[0015] Preferably, two ends of the projection of the fiber Bragg grating on the axis of the multi-core optical fiber extend from two ends of the projection of the metal film on the axis of the multi-core optical fiber, ensuring that the heat generated by the metal film is transferred to the fiber Bragg grating more efficiently.

[0016] Preferably, the projection of the fiber Bragg grating on the axis of the multi-core optical fiber coincides with the projection of the metal film on the axis of the multi-core optical fiber, thereby ensuring the utilization rate of the fiber Bragg grating.

[0017] Preferably, the metal film is a silver film.

[0018] The present invention also provides a wind speed measuring device, which includes the above-mentioned wind speed sensor, a fiber grating wavelength demodulator, a pump light source and a photon lantern;

[0019] The output end of the pump light source is connected to the first input end of the photon lantern, and the pump light source generates pump light to input the photon lantern;

[0020] The output end of the fiber Bragg grating wavelength demodulator is connected to the second input end of the photon lantern, and the fiber Bragg grating wavelength demodulator generates signal light which is input into the photon lantern;

[0021] The output end of the photon lantern is close to the end of the wind speed sensor where the long-period fiber grating is located. The pump light is injected into the core of the multi-core optical fiber provided with the long-period fiber grating, and the signal light is injected into the core of the multi-core optical fiber provided with the fiber Bragg grating; the pump light is coupled to the optical fiber cladding through the long-period fiber grating and absorbed by the metal film; the signal light is reflected by the fiber Bragg grating and input into the fiber grating wavelength demodulator by the photon lantern.

[0022] Preferably, the wavelength of the pump light generated by the pump light source is included in the resonance peak of the long-period fiber grating.

[0023] The pump light source is used to generate pump light. The wavelength of the pump light must be included in the resonance peak of the long-period fiber grating. It is injected into the core of the multi-core optical fiber provided with the long-period fiber grating through a photon lantern, and the long-period fiber grating couples the pump light to the optical fiber cladding. The optical fiber cladding of the multi-core optical fiber is coated with a metal film. After the metal film absorbs the energy of the pump light, the temperature rises, and then the temperature of the fiber Bragg grating also rises. The signal light generated by the fiber Bragg grating wavelength demodulator is injected into the core of the multi-core optical fiber provided with the fiber Bragg grating through the photon lantern. After the signal light is reflected by the fiber Bragg grating, it is input into the fiber Bragg grating wavelength demodulator by the photon lantern, and the fiber Bragg grating wavelength demodulator can analyze the wavelength of the reflected light. As the temperature of the fiber Bragg grating increases, the reflected wavelength redshifts. When the wind speed is not zero, the temperature of the metal film decreases, the temperature of the fiber Bragg grating also decreases, and the reflected wavelength blueshifts. There is a fixed relationship between the blueshift amount and the wind speed. The wind speed can be demodulated by measuring the blueshift amount of the reflected wavelength.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] The present invention arranges a long-period fiber grating and a fiber Bragg grating in different cores of a multi-core optical fiber, so that signal light and pump light are transmitted separately, the pump light does not interfere with the signal light and the reflected light, and the signal light loss is small; the metal film coated on the circumference of the multi-core optical fiber is used to generate temperature changes and cause the temperature changes of the fiber Bragg grating, thereby causing the wavelength of the signal light reflected by the fiber Bragg grating to change, and obtain wind speed information; the present invention has a simple structure, a small volume, and a high sensitivity, and can measure accurate wind speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a schematic structural diagram of a fiber grating hot-wire wind speed sensor based on a multi-core optical fiber as described in Example 1.

[0027] Figure 2 This is a schematic diagram of the structure of a fiber grating hot wire wind speed sensor based on multi-core optical fiber described in Example 2.

[0028] Figure 3 This is a schematic structural diagram of a fiber grating hot wire wind speed sensor based on a multi-core optical fiber as described in Example 3.

[0029] Figure 4 This is a schematic structural diagram of a fiber grating hot-wire wind speed sensor based on a multi-core optical fiber as described in Example 4.

[0030] Figure 5 This is a schematic structural diagram of a fiber grating hot-wire wind speed sensor based on a multi-core optical fiber as described in Example 5.

[0031] Figure 6 This is a schematic structural diagram of a wind speed measuring device described in Example 6.

[0032] In the figure, 1-multi-core optical fiber, 2-long period fiber Bragg grating, 3-fiber Bragg grating, 4-metal film, 5-fiber Bragg grating wavelength demodulator, 6-pump light source, 7-photon lantern. DETAILED DESCRIPTION

[0033] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0034] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0035] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0036] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] Example 1

[0038] This embodiment provides a fiber grating hot wire wind speed sensor based on a multi-core optical fiber. Figure 1 As shown, the wind speed sensor includes a multi-core optical fiber 1, a long-period fiber grating 2, a fiber Bragg grating 3 and a metal film 4.

[0039] The long-period fiber grating 2 and the fiber Bragg grating 3 are arranged in different cores of the multi-core optical fiber 1 ; the metal film 4 is coated on the circumference of the multi-core optical fiber 1 ; the length of the long-period fiber grating 2 is greater than that of the fiber Bragg grating 3 .

[0040] The projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1; the projection of the metal film 4 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1. The two ends of the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1 extend from the two ends of the projection of the metal film 4 on the axis of the multi-core optical fiber 1;

[0041] In the specific implementation process, in the wind speed sensor provided by this embodiment, there is a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 and the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, and the distance d is 3 mm; the projection length of the metal film 4 on the axis of the multi-core optical fiber 1 is shorter than the projection length of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, ensuring that the heat generated by the metal film 4 is transferred to the fiber Bragg grating 3 with higher efficiency; but there is also a distance from the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1, avoiding the temperature change of the metal film 4 from affecting the transmission spectrum of the long-period fiber grating 2; in this embodiment, the metal film 4 is a silver film.

[0042] Example 2

[0043] This embodiment provides a fiber grating hot wire wind speed sensor based on a multi-core optical fiber. Figure 2 As shown, the wind speed sensor includes a multi-core optical fiber 1, a long-period fiber grating 2, a fiber Bragg grating 3 and a metal film 4.

[0044] The long-period fiber grating 2 and the fiber Bragg grating 3 are arranged in different cores of the multi-core optical fiber 1 ; the metal film 4 is coated on the circumference of the multi-core optical fiber 1 ; the length of the long-period fiber grating 2 is greater than that of the fiber Bragg grating 3 .

[0045] The projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1; the projection of the metal film 4 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1. Both ends of the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1 extend from both ends of the projection of the metal film 4 on the axis of the multi-core optical fiber 1.

[0046] In the specific implementation process, in the wind speed sensor provided by this embodiment, there is a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 and the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, and the distance d is 5 mm; the projection length of the metal film 4 on the axis of the multi-core optical fiber 1 is shorter than the projection length of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, ensuring that the heat generated by the metal film 4 is transferred to the fiber Bragg grating 3 with higher efficiency; but there is also a distance from the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1, avoiding the temperature change of the metal film 4 from affecting the transmission spectrum of the long-period fiber grating 2; in this embodiment, the metal film 4 is a silver film.

[0047] Example 3

[0048] This embodiment provides a fiber grating hot wire wind speed sensor based on a multi-core optical fiber. Figure 3 As shown, the wind speed sensor includes a multi-core optical fiber 1, a long period fiber grating 2, a fiber Bragg grating 3 and a metal film 4;

[0049] The long-period fiber grating 2 and the fiber Bragg grating 3 are arranged in different cores of the multi-core optical fiber 1; the metal film 4 is coated on the circumference of the multi-core optical fiber 1; the length of the long-period fiber grating 2 is greater than the length of the fiber Bragg grating 3;

[0050] The projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1; the projection of the metal film 4 on the axis of the multi-core optical fiber 1 coincides with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1;

[0051] In the specific implementation process, the wind speed sensor provided by this embodiment has a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 and the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, and the distance d is 3 mm; the projection length of the metal film 4 on the axis of the multi-core optical fiber 1 coincides with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, which not only ensures the efficiency of the heat generated by the metal film 4 to be transferred to the fiber Bragg grating 3, but also ensures the utilization rate of the fiber Bragg grating; there is also a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1, and the distance is also 3 mm, so as to avoid the temperature change of the metal film 4 from affecting the transmission spectrum of the long-period fiber grating 2; in this embodiment, the metal film 4 is a silver film.

[0052] Example 4

[0053] This embodiment provides a fiber grating hot wire wind speed sensor based on a multi-core optical fiber. Figure 4 As shown, the wind speed sensor includes a multi-core optical fiber 1, a long period fiber grating 2, a fiber Bragg grating 3 and a metal film 4;

[0054] The long-period fiber grating 2 and the fiber Bragg grating 3 are arranged in different cores of the multi-core optical fiber 1; the metal film 4 is coated on the circumference of the multi-core optical fiber 1; the length of the long-period fiber grating 2 is greater than the length of the fiber Bragg grating 3;

[0055] The projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1; the projection of the metal film 4 on the axis of the multi-core optical fiber 1 coincides with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1;

[0056] In the specific implementation process, in the wind speed sensor provided by this embodiment, there is a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 and the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, and the distance d is 4 mm; the projection length of the metal film 4 on the axis of the multi-core optical fiber 1 coincides with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, which not only ensures the efficiency of the heat generated by the metal film 4 to be transferred to the fiber Bragg grating 3, but also ensures the utilization rate of the fiber Bragg grating; there is also a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1, and the distance is also 4 mm, so as to avoid the temperature change of the metal film 4 from affecting the transmission spectrum of the long-period fiber grating 2; in this embodiment, the metal film 4 is a silver film.

[0057] Example 5

[0058] This embodiment provides a fiber grating hot wire wind speed sensor based on a multi-core optical fiber. Figure 5 As shown, the wind speed sensor includes a multi-core optical fiber 1, a long period fiber grating 2, a fiber Bragg grating 3 and a metal film 4;

[0059] The long-period fiber grating 2 and the fiber Bragg grating 3 are arranged in different cores of the multi-core optical fiber 1; the metal film 4 is coated on the circumference of the multi-core optical fiber 1; the length of the long-period fiber grating 2 is greater than the length of the fiber Bragg grating 3;

[0060] The projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 does not overlap with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1; the projection of the metal film 4 on the axis of the multi-core optical fiber 1 coincides with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1;

[0061] In the specific implementation process, in the wind speed sensor provided by this embodiment, there is a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1 and the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, and the distance d is 5 mm; the projection length of the metal film 4 on the axis of the multi-core optical fiber 1 coincides with the projection of the fiber Bragg grating 3 on the axis of the multi-core optical fiber 1, which not only ensures the efficiency of the heat generated by the metal film 4 to be transferred to the fiber Bragg grating 3, but also ensures the utilization rate of the fiber Bragg grating; there is also a distance between the projection of the long-period fiber grating 2 on the axis of the multi-core optical fiber 1, and the distance is also 5 mm, so as to avoid the temperature change of the metal film 4 from affecting the transmission spectrum of the long-period fiber grating 2; in this embodiment, the metal film 4 is a silver film.

[0062] Example 6

[0063] This embodiment provides a wind speed measuring device, such as Figure 6 As shown, it includes the wind speed sensor, fiber grating wavelength demodulator 5, pump light source 6 and photon lantern 7 described in any of the above embodiments.

[0064] The output end of the pump light source 6 is connected to the first input end of the photon lantern 7 . The pump light source 6 generates pump light which is input into the photon lantern 7 . The wavelength of the pump light generated by the pump light source 6 is included in the resonance peak of the long-period fiber grating 2 .

[0065] The output end of the fiber grating wavelength demodulator 5 is connected to the second input end of the photon lantern 7, and the fiber grating wavelength demodulator 5 generates a signal light which is input into the photon lantern 7;

[0066] The output end of the photon lantern 7 is close to the end where the long-period fiber grating 2 in the wind speed sensor is located. The pump light is injected into the core of the multi-core optical fiber 1 provided with the long-period fiber grating 2, and the signal light is injected into the core of the multi-core optical fiber 1 provided with the fiber Bragg grating 3; the pump light is coupled to the metal film 4 through the long-period fiber grating 2; the signal light is reflected by the fiber Bragg grating 3 and input into the fiber grating wavelength demodulator 5 by the photon lantern 7.

[0067] In the specific implementation process, the device provided by this embodiment is placed in an environment where wind speed needs to be measured. The pump light source 6 is used to generate pump light, which is injected into the core of the multi-core optical fiber 1 provided with a long-period fiber grating 2 through the photon lantern 7. The long-period fiber grating 2 couples the pump light to the optical fiber cladding; the optical fiber cladding of the multi-core optical fiber 1 is coated with a metal film 4. After the metal film 4 absorbs the pump light, its temperature rises, thereby causing the temperature of the fiber Bragg grating 3 to also rise; the signal light generated by the fiber grating wavelength demodulator 5 is injected into the device through the photon lantern 7. A fiber Bragg grating 3 is placed in the core of a multi-core optical fiber 1; after the signal light is reflected by the fiber Bragg grating 3, it is input into the fiber Bragg grating wavelength demodulator 5 by the photon lantern 7, and the fiber Bragg grating wavelength demodulator 5 can analyze the wavelength of the reflected light; as the temperature of the fiber Bragg grating 3 increases, the reflected wavelength red-shifts, and when the wind speed is not zero, the temperature of the metal film 4 decreases, the temperature of the fiber Bragg grating 3 also decreases, and the reflected wavelength blue-shifts. There is a fixed relationship between the blue-shift amount and the wind speed, and the wind speed can be demodulated by measuring the blue-shift amount of the reflected wavelength.

[0068] The specific calculation method is:

[0069] When the heat generated by the metal film absorbing the pump light is equal to the heat transferred by the sensor to the surrounding air, the thermal equilibrium state is reached. The thermal equilibrium state equation is:

[0070]

[0071] Where P is the energy of the pump light input into the optical fiber, is the coupling efficiency, a Ag represents the absorption efficiency of the silver film to the pump light, H loss Indicates the heat lost by the sensor to the air;

[0072] According to the heat transfer theorem and Newton's cooling law, the heat H lost by the sensor to the air loss It is expressed as:

[0073]

[0074] Where, T (v) Indicates the temperature of the sensor, T e represents the ambient temperature, A and B represent the empirical calibration constants, and v represents the wind speed; then the temperature of the sensor T (v) The relationship with wind speed v is:

[0075]

[0076] The relationship between the center wavelength drift of the fiber Bragg grating and the temperature change is:

[0077] Δλ=λ0(α Λ +ζ)ΔT

[0078] ΔT=T (v) -T e

[0079] Δλ=λ-λ0

[0080] In the formula, Δλ represents the central wavelength drift of the fiber Bragg grating, λ0 represents the initial wavelength of the fiber Bragg grating before heating, λ represents the wavelength of the fiber Bragg grating at the current heating moment, and α Λ represents the thermal expansion coefficient of the multi-core optical fiber, ζ represents the thermo-optical coefficient of the multi-core optical fiber;

[0081] The relationship between the wavelength λ and wind speed v of the fiber Bragg grating at the current heating moment is obtained:

[0082]

[0083] The same or similar reference numerals correspond to the same or similar components;

[0084] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0085] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A wind speed measuring device, characterized in that: The device comprises a fiber grating hot-wire wind speed sensor based on a multi-core optical fiber, a fiber grating wavelength demodulator (5), a pump light source (6) and a photon lantern (7); The output end of the pump light source (6) is connected to the first input end of the photon lantern (7), and the pump light source (6) generates pump light which is input into the photon lantern (7); The output end of the fiber grating wavelength demodulator (5) is connected to the second input end of the photon lantern (7), and the fiber grating wavelength demodulator (5) generates signal light which is input into the photon lantern (7); The fiber Bragg grating hot-wire wind speed sensor based on a multi-core optical fiber comprises a multi-core optical fiber (1), a long-period optical fiber grating (2), a fiber Bragg grating (3) and a metal film (4); The long-period fiber grating (2) and the fiber Bragg grating (3) are arranged in different cores of the multi-core optical fiber (1); the metal film (4) is coated on the circumference of the multi-core optical fiber (1); The projection of the long-period fiber grating (2) on the axis of the multi-core optical fiber (1) does not overlap with the projection of the fiber Bragg grating (3) on the axis of the multi-core optical fiber (1); The projection of the metal film (4) on the axis of the multi-core optical fiber (1) does not overlap with the projection of the long-period optical fiber grating (2) on the axis of the multi-core optical fiber (1); The output end of the photon lantern (7) is close to the end of the wind speed sensor where the long-period fiber grating (2) is located, and the pump light is injected into the core of the multi-core optical fiber (1) provided with the long-period fiber grating (2), and the signal light is injected into the core of the multi-core optical fiber (1) provided with the fiber Bragg grating (3); the pump light is coupled to the optical fiber cladding through the long-period fiber grating (2) and absorbed by the metal film (4); the signal light is reflected by the fiber Bragg grating (3) and then input into the fiber grating wavelength demodulator (5) through the photon lantern (7).

2. The wind speed measuring device according to claim 1, characterized in that: The length of the long-period fiber grating (2) is greater than the length of the fiber Bragg grating (3).

3. The wind speed measuring device according to claim 2, characterized in that: The distance range d between the projection of the long-period fiber grating (2) on the axis of the multi-core optical fiber (1) and the projection of the fiber Bragg grating (3) on the axis of the multi-core optical fiber (1) is 3-5 mm.

4. The wind speed measuring device according to claim 3, characterized in that: Two ends of the projection of the fiber Bragg grating (3) on the axis of the multi-core optical fiber (1) extend from two ends of the projection of the metal film (4) on the axis of the multi-core optical fiber (1).

5. The wind speed measuring device according to claim 4, characterized in that: The projection of the fiber Bragg grating (3) on the axis of the multi-core optical fiber (1) coincides with the projection of the metal film (4) on the axis of the multi-core optical fiber (1).

6. The wind speed measuring device according to claim 1, characterized in that: The metal film (4) is a silver film.

7. The wind speed measuring device according to claim 1, characterized in that: The wavelength of the pump light generated by the pump light source (6) is included in the resonance peak of the long-period fiber grating (2).

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