Optical fiber magnetic field and temperature measurement device and method based on cascaded MZI

Abstract

The application discloses a fiber magnetic field and temperature measuring device and method based on a cascade MZI, and relates to the technical field of optical fiber sensing. The device comprises a broadband light source, a sensor and a spectrum analyzer. The sensor comprises a quartz tube and a first single-mode optical fiber, a first few-mode optical fiber, a magnetic fluid filled side-hole optical fiber, a UV glue film coated hollow-core optical fiber, a second few-mode optical fiber and a second single-mode optical fiber which are sequentially fused. The fiber core and the magnetic fluid cavity in the magnetic fluid filled side-hole optical fiber constitute a first MZI. The hollow-core fiber core and the second cladding in the UV glue film coated hollow-core optical fiber constitute a second MZI. The first few-mode optical fiber expands the light beam introduced by the first single-mode optical fiber, and then introduces the light beam into the second few-mode optical fiber through the first MZI and the second MZI for coupling. The coupled light beam is demodulated, a coefficient matrix is used for calculation, and the dual-parameter measurement of the magnetic field and the temperature is realized. The application aims to realize the simultaneous detection of the dual parameters of the magnetic field and the temperature, and has high sensitivity.

Description

Technical Field

[0001] This application relates to the field of fiber optic sensing technology, and in particular to a fiber optic magnetic field and temperature measurement device and method based on cascaded MZI. Background Technology

[0002] As crucial characterizing parameters in industrial production, scientific research, and daily life, the accurate measurement of magnetic fields and temperatures is essential for fields such as biomedicine, aerospace, and power systems. Fiber optic sensors have attracted widespread attention from researchers due to their corrosion resistance, electromagnetic interference immunity, and ability to perform remote multi-parameter detection, compensating for the shortcomings of traditional sensors in numerous application areas. Various fiber optic sensors based on the fiber interferometer mechanism have been proposed and applied to the measurement of magnetic fields and temperatures. Currently known techniques achieve temperature and magnetic field measurements by splicing a multimode fiber with two single-mode fiber segments at an offset midpoint and cascading fiber Bragg gratings. Another technique involves encapsulating two single-mode fiber segments within a quartz tube to create a Fabry-Perot cavity, and then cascading fiber Bragg gratings attached to the surface of a strain gauge to achieve temperature and magnetic field measurements. However, all of these techniques require the use of fiber Bragg gratings for magnetic field and temperature measurements, increasing costs and also suffering from low sensitivity and poor mechanical stress due to asymmetric structures. Summary of the Invention

[0003] The purpose of this application is to provide a fiber optic magnetic field and temperature measurement device and method based on cascaded MZI, which can realize the simultaneous detection of two parameters, magnetic field and temperature, with high sensitivity.

[0004] To achieve the above objectives, this application provides the following solution:

[0005] In a first aspect, this application provides a fiber optic magnetic field and temperature measurement device based on cascaded MZI, including: a host computer, a broadband light source, a sensor, and a spectrometer;

[0006] The broadband light source is connected to the sensor; the sensor is connected to the spectrometer; the host computer is connected to the spectrometer.

[0007] The sensor includes a quartz tube and a first single-mode fiber, a first few-mode fiber, a magnetic fluid-filled side-hole fiber, a UV-coated hollow fiber, a second few-mode fiber, and a second single-mode fiber, which are sequentially fused together.

[0008] The magnetic fluid-filled side-hole optical fiber includes a core, a first cladding, and a magnetic fluid cavity; the core and the magnetic fluid cavity constitute a first MZI; the quartz tube is used to encapsulate the first MZI.

[0009] The UV-coated hollow optical fiber comprises a hollow fiber core, a second cladding, and a UV coating; the hollow fiber core and the second cladding constitute a second MZI.

[0010] The first single-mode fiber is used to guide the light beam emitted by the broadband light source into the first few-mode fiber;

[0011] The first few-mode fiber is used to expand the beam and then sequentially guide it into the side-hole fiber filled with magnetic fluid and the hollow fiber coated with UV film, and then guide it into the second few-mode fiber through the first MZI and the second MZI; the second few-mode fiber is used to couple the received beam to obtain a coupled beam.

[0012] The second single-mode fiber is used to guide the coupled beam to the spectrometer;

[0013] The spectrometer is used to demodulate the coupled beam to obtain the corresponding interference spectrum;

[0014] The host computer is used to perform calculations based on the interference spectrum using a coefficient matrix to achieve dual-parameter measurement of magnetic field and temperature.

[0015] Optionally, the fiber optic magnetic field and temperature measurement device based on cascaded MZI further includes: an inlet single-mode fiber and an outlet single-mode fiber;

[0016] The inlet single-mode fiber is connected to the broadband light source and the sensor respectively; the outlet single-mode fiber is connected to the sensor and the spectrometer respectively.

[0017] The single-mode optical fiber is used to transmit the light beam emitted by the broadband light source to the sensor;

[0018] The single-mode fiber is used to transmit the coupled beam to the spectrometer.

[0019] Optionally, the diameter of the fiber core is 9 micrometers.

[0020] Optionally, the first cladding has pores inside; the diameter of the pores is 40 micrometers, and the outer diameter of the side-hole fiber is 125 micrometers.

[0021] Optionally, the hollow fiber has an inner diameter of 10 micrometers and an outer diameter of 125 micrometers.

[0022] Optionally, the length range of the first few-mode fiber and the second few-mode fiber is 500 micrometers to 1000 micrometers; the length range of the magnetic fluid-filled side-hole fiber is 200 micrometers to 300 micrometers; and the length range of the UV-coated hollow fiber is 600 micrometers to 700 micrometers.

[0023] Optionally, the thickness of the UV film ranges from 25 micrometers to 30 micrometers.

[0024] Secondly, this application provides a method for measuring the magnetic field and temperature of an optical fiber based on a cascaded MZI, wherein the method is implemented using the aforementioned cascaded MZI-based optical fiber magnetic field and temperature measuring device; the method includes:

[0025] A coupled beam is obtained; the coupled beam is obtained by expanding the beam emitted by the broadband light source through the first few-mode fiber, and then guiding it into the side-hole fiber filled with magnetic fluid and the hollow fiber coated with UV film. After interference by the first MZI and the second MZI, it is coupled by the second few-mode fiber.

[0026] The coupled beam is demodulated, and the coefficient matrix is ​​used to calculate the interference spectrum obtained by demodulation in order to realize the dual-parameter measurement of magnetic field and temperature.

[0027] Optionally, the expression for the interference spectral function corresponding to the first MZI is:

[0028]

[0029] The expression for the interference spectral function corresponding to the second MZI is:

[0030]

[0031] The expression for the interference spectrum function of the coupled beam obtained by coupling using a second few-mode fiber is:

[0032] I sensor =I MZI1 ·I MZI2 ;

[0033] Among them, I MZI1 I1 is the interference spectral function corresponding to the first MZI; I2 is the optical energy transmitted in the core of the magnetohydrodynamic (MHD) filled side-hole fiber; I2 is the optical energy transmitted in the MHD cavity; Δn eff1 L1 is the effective refractive index difference between the fiber core and the magnetohydrodynamic cavity; L1 is the length of the magnetohydrodynamic-filled side-hole fiber; λ is the wavelength of the incident beam; I MZI2 I2 is the interference spectral function corresponding to the second MZI; I3 is the light energy transmitted in the hollow fiber core; I4 is the light energy transmitted in the second cladding; Δn eff2 l1 represents the effective refractive index difference between the hollow fiber core and the second cladding; l2 represents the length of the UV-coated hollow fiber; I sensor The interference spectrum function corresponding to the coupled beam; In the first MZI, the phase difference between the beam transmitted through the fiber core and the beam transmitted through the magnetohydrodynamic cavity; In the second MZI, the phase difference is the beam transmitted in the hollow fiber core and the beam transmitted in the second cladding.

[0034] Optionally, the coupled beam is demodulated, and the coefficient matrix is ​​used to calculate the interference spectrum obtained from the demodulation to achieve dual-parameter measurement of magnetic field and temperature, specifically including:

[0035] Based on the interference spectrum function corresponding to the coupled beam, the coupled beam is demodulated to determine the interference spectrum corresponding to the coupled beam;

[0036] The wavelength shift is determined based on the interference spectrum; the wavelength shift includes: a first MZI wavelength shift and a second MZI wavelength shift;

[0037] The wavelength drift is calculated using a coefficient matrix to achieve dual-parameter measurement of magnetic field and temperature; wherein the expression for the coefficient matrix is:

[0038]

[0039] Where ΔT is the change in external temperature; ΔH is the change in external magnetic field strength; S MZI1-T The temperature sensitivity of the first MZI; S MZI2-T The temperature sensitivity of the second MZI; S MZI1-H The magnetic field sensitivity of the first MZI; S MZI2-H The magnetic field sensitivity of the second MZI; Δλ MZI1 Δλ represents the wavelength shift of the first MZI. MZI2 This is the second MZI wavelength shift.

[0040] According to the specific embodiments provided in this application, this application has the following technical effects:

[0041] This application provides a fiber optic magnetic field and temperature measurement device and method based on cascaded MZIs. The device includes: a broadband light source, a sensor, and a spectrometer. The sensor includes a quartz tube and sequentially fused together a first single-mode fiber, a first few-mode fiber, a magnetic fluid-filled side-hole fiber, a UV-coated hollow fiber, a second few-mode fiber, and a second single-mode fiber. The core and magnetic fluid cavity in the magnetic fluid-filled side-hole fiber constitute the first MZI. The hollow core and the second cladding in the UV-coated hollow fiber constitute the second MZI. The first few-mode fiber expands the beam introduced by the first single-mode fiber, and then couples it into the second few-mode fiber through the first and second MZIs. The spectrometer demodulates the beam, and then the calculation is performed using a coefficient matrix on a host computer to achieve dual-parameter measurement of magnetic field and temperature. This application improves the sensor's integration by using a cascaded MZI structure, enhances its detection sensitivity by combining the magnetic sensitivity of a magnetohydrodynamic fluid with the temperature sensitivity of a UV film, and achieves dual-parameter measurement using coefficient matrix demodulation. This enables high sensitivity and simultaneous measurement of both magnetic field and temperature parameters. Furthermore, the sensor provided in this application exhibits high sensitivity, high integration, and structural stability. Therefore, this application can achieve simultaneous detection of both magnetic field and temperature parameters with high sensitivity. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A schematic diagram of the fiber optic magnetic field and temperature measurement device based on cascaded MZI provided for this application;

[0044] Figure 2 This is a schematic diagram of the sensor structure provided in this application;

[0045] Figure 3 A schematic diagram of the cross-section of the optical fiber provided in this application; wherein, Figure 3 (a) in the figure is a schematic diagram of a side-hole optical fiber filled with magnetofluid. Figure 3 (b) is a schematic diagram of a hollow optical fiber coated with UV adhesive film;

[0046] Figure 4 The spectrum provided for this application; wherein, Figure 4 (a) in the diagram is a schematic diagram of the first MZI spectrum. Figure 4 (b) in the diagram is a schematic diagram of the second MZI spectrum. Figure 4 (c) in the diagram is a schematic diagram of the sensor spectrum;

[0047] Figure 5 The response graph of the spectrum of the sensor provided in this application as a function of external temperature;

[0048] Figure 6 The response graph of the spectrum of the sensor provided in this application as a function of the external magnetic field strength.

[0049] Figure reference numerals: Broadband light source-1; Inlet single-mode fiber-2; Sensor-3; Outlet single-mode fiber-4; Spectrometer-5; Host computer-6; First single-mode fiber-31; First few-mode fiber-32; Side-hole fiber-33; Hollow-core fiber-34; Second few-mode fiber-35; Second single-mode fiber-36; Quartz tube-37; Opening-38; Magnetohydrodynamic cavity-39; UV film-310. Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] To address the problems of low sensitivity, poor structural stability, and low accuracy in dual-parameter measurement of existing fiber optic magnetic field and temperature sensors, this application proposes a cascaded MZI-based fiber optic magnetic field and temperature sensor based on the properties of magnetohydrodynamics and UV films, the principle of a fiber optic Mach-Zehnder interferometer (MZI), and the coefficient matrix demodulation mechanism. This fiber optic sensor exhibits high sensitivity, high integration, and structural stability, enabling simultaneous measurement of magnetic field and temperature. Specifically, this application achieves high-sensitivity, simultaneous dual-parameter measurement of magnetic field and temperature by cascading MZI, combining magnetohydrodynamics and UV films, and utilizing coefficient matrix demodulation. Furthermore, the sensor provided in this application features a stable structure, high integration, and high sensitivity, enabling simultaneous detection of magnetic field and temperature.

[0052] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] In one exemplary embodiment, such as Figure 1 As shown, a fiber optic magnetic field and temperature measurement device based on cascaded MZI is provided. The device includes: a host computer 6, a broadband light source 1, a sensor 3, and a spectrometer 5. The broadband light source 1 is connected to the sensor 3; the sensor 3 is connected to the spectrometer 5. The host computer 6 is connected to the spectrometer 5.

[0054] like Figure 2 As shown, the sensor 3 includes a quartz tube 37 and a first single-mode fiber 31, a first few-mode fiber 32, a side-hole fiber 33 filled with magnetic fluid, a hollow fiber 34 coated with UV film 310, a second few-mode fiber 35, and a second single-mode fiber 36, which are sequentially fused together.

[0055] The magnetic fluid-filled side-hole optical fiber 33 includes a fiber core, a first cladding, and a magnetic fluid cavity 39; the fiber core and the magnetic fluid cavity 39 constitute a first MZI; a quartz tube 37 is used to encapsulate the first MZI; the hollow-core optical fiber 34 coated with a UV film 310 includes a hollow fiber core, a second cladding, and a UV film 310; the hollow fiber core and the second cladding constitute a second MZI. The surface of the hollow-core optical fiber is coated with a UV film 310.

[0056] The first single-mode fiber 31 is used to guide the beam emitted by the broadband light source 1 into the first few-mode fiber 32; the first few-mode fiber 32 is used to expand the beam and then sequentially guide it into the side-hole fiber 33 filled with magnetic fluid and the hollow fiber 34 coated with UV film 310, and then guide it into the second few-mode fiber 35 through the first MZI and the second MZI; the second few-mode fiber 35 is used to couple the received beam to obtain a coupled beam.

[0057] The second single-mode fiber 36 is used to guide the coupled beam to the spectrometer 5; the spectrometer 5 is used to demodulate the coupled beam to obtain the corresponding interference spectrum. The host computer 6 is used to perform calculations based on the interference spectrum using a coefficient matrix to achieve dual-parameter measurement of magnetic field and temperature.

[0058] In one embodiment, the fiber optic magnetic field and temperature measurement device based on cascaded MZI further includes: an inlet single-mode fiber 2 and an outlet single-mode fiber 4; the inlet single-mode fiber 2 is connected to the broadband light source 1 and the sensor 3 respectively; the outlet single-mode fiber 4 is connected to the sensor 3 and the spectrometer 5 respectively.

[0059] The single-mode fiber 2 is used to transmit the light beam emitted by the broadband light source 1 to the sensor 3; the single-mode fiber 4 is used to transmit the coupled light beam to the spectrometer 5.

[0060] The beam emitted by the broadband light source 1 is transmitted to the sensor 3 through the single-mode fiber 2. The incident beam is transmitted to the first few-mode fiber 32 through the first single-mode fiber 31. After being expanded by the first few-mode fiber 32, it is transmitted to the second few-mode fiber 35 through the first MZI and the second MZI in sequence. After being coupled by the second few-mode fiber 35, it is output from the second single-mode fiber 36. The emitted beam is transmitted to the spectrometer 5 through the single-mode fiber 4.

[0061] The first MZI is sensitive to both temperature and magnetic field, while the second MZI is only sensitive to temperature. When the external temperature and magnetic field strength change simultaneously, the host computer 6 can perform calculations using the coefficient matrix to achieve dual-parameter measurement of temperature and magnetic field.

[0062] like Figure 2 As shown, the sensor mentioned in this application includes a first single-mode fiber 31, a first few-mode fiber 32, a side-hole fiber 33, a hollow fiber 34, a second few-mode fiber 35, a second single-mode fiber 36, a quartz tube 37, an opening 38, a magnetohydrodynamic cavity 39, and a UV film 310.

[0063] The first single-mode fiber 31 is used to guide the incident light beam into the first few-mode fiber 32; the first few-mode fiber 32 is used to expand the incident light beam and then sequentially guide it into the magnetic fluid-filled side-hole fiber 33 and the UV-coated hollow fiber 34. Figure 3 As shown in (a), the magnetohydrodynamic (MZI) filled side-hole fiber 33 includes a core, a first cladding, and a magnetohydrodynamic cavity 39. The core and the MZI of the MZI are composed of a core and a first cladding. A quartz tube 37 is used to encapsulate the first MZI. Figure 3 As shown in (b), the hollow optical fiber 34 coated with UV film 310 includes an air core, a second cladding, and UV film 310. The air core and the second cladding of the hollow optical fiber 34 coated with UV film 310 constitute a second MZI. Figure 2 As shown, the beam expanded by the first few-mode fiber 32 is sequentially guided into the second few-mode fiber 35 through the first MZI and the second MZI. The second few-mode fiber 35 is used to couple the beam and guide it into the second single-mode fiber 36. The second single-mode fiber 36 is used to guide the emitted beam out. The side-hole fiber 33 has an opening 38 on one side for filling with magnetic fluid.

[0064] As an alternative implementation, the fiber core has a diameter of 9 micrometers. The first cladding has internal pores with a diameter of 40 micrometers, and the outer diameter of the side-hole fiber is 125 micrometers. The hollow-core fiber has an inner diameter of 10 micrometers and an outer diameter of 125 micrometers. The lengths of both the first and second few-mode fibers range from 500 to 1000 micrometers; the length of the magnetofluid-filled side-hole fiber ranges from 200 to 300 micrometers; and the length of the UV-coated hollow-core fiber ranges from 600 to 700 micrometers. The thickness of the UV coating ranges from 25 to 30 micrometers.

[0065] The core diameter of both the first single-mode fiber and the second single-mode fiber ranges from 8 to 9 micrometers, and the outer diameter is 125 micrometers. The core diameter of both the first few-mode fiber and the second few-mode fiber is 70 micrometers, and the outer diameter is 125 micrometers.

[0066] The side-hole optical fiber filled with magnetorheological fluid has an opening on one side for filling with magnetorheological fluid. The opening diameter is 15-20 micrometers and the opening density is 20-25 openings / mm. The inner diameter of the quartz tube is 125 micrometers and the outer diameter is 200 micrometers.

[0067] The sensor mentioned in this application is a fiber optic magnetic field and temperature sensor based on cascaded MZI, and its fabrication method includes:

[0068] The first single-mode fiber, the first few-mode fiber, the side-hole fiber, the hollow fiber, the second few-mode fiber, and the second single-mode fiber are sequentially fused together. An opening is created on one side of the air hole of the side-hole fiber using a femtosecond laser. Based on the opening, magnetic fluid is injected into the air hole of the side-hole fiber to form a magnetic fluid cavity. The magnetic fluid-filled side-hole fiber is encapsulated using a quartz tube. The surface of the hollow fiber is coated with UV adhesive to form a UV adhesive film on the surface of the hollow fiber. After curing with a UV lamp, the sensor fabrication is completed.

[0069] In an exemplary embodiment, a method for measuring the magnetic field and temperature of an optical fiber based on a cascaded MZI is provided. This method is implemented using a cascaded MZI-based optical fiber magnetic field and temperature measuring device. The method includes:

[0070] The coupled beam is obtained by expanding the beam emitted by the broadband light source through the first few-mode fiber, then guiding it into the side-hole fiber filled with magnetic fluid and the hollow fiber coated with UV film. After interference by the first MZI and the second MZI, the beam is coupled using the second few-mode fiber.

[0071] The coupled beam is demodulated, and the coefficient matrix is ​​used to calculate the interference spectrum obtained by demodulation in order to achieve dual-parameter measurement of magnetic field and temperature.

[0072] The expression for the interference spectral function corresponding to the first MZI is:

[0073]

[0074] The expression for the interference spectral function corresponding to the second MZI is:

[0075]

[0076] The expression for the interference spectrum function of the coupled beam obtained by coupling using a second few-mode fiber is:

[0077] I sensor =I MZI1 ·I MZI2 .

[0078] Among them, I MZI1I1 is the interference spectral function corresponding to the first MZI; I2 is the optical energy transmitted in the core of the magnetohydrodynamic (MHD) filled side-hole fiber; I2 is the optical energy transmitted in the MHD cavity; Δn eff1 L1 is the effective refractive index difference between the fiber core and the magnetohydrodynamic cavity; L1 is the length of the magnetohydrodynamic-filled side-hole fiber; λ is the wavelength of the incident beam; I MZI2 I2 is the interference spectral function corresponding to the second MZI; I3 is the light energy transmitted in the hollow fiber core; I4 is the light energy transmitted in the second cladding; Δn eff2 L1 represents the effective refractive index difference between the hollow fiber core and the second cladding; L2 represents the length of the UV-coated hollow fiber; I sensor The interference spectrum function corresponding to the coupled beam; In the first MZI, the phase difference between the beam transmitted through the fiber core and the beam transmitted through the magnetohydrodynamic cavity; In the second MZI, the phase difference is the beam transmitted in the hollow fiber core and the beam transmitted in the second cladding.

[0079] In one embodiment, the coupled beam is demodulated, and a coefficient matrix is ​​used to calculate the interference spectrum obtained from the demodulation to achieve dual-parameter measurement of magnetic field and temperature, specifically including:

[0080] Based on the interference spectrum function corresponding to the coupled beam, the coupled beam is demodulated to determine the interference spectrum corresponding to the coupled beam; the wavelength drift is determined based on the interference spectrum; the wavelength drift includes: the first MZI wavelength drift and the second MZI wavelength drift.

[0081] The wavelength drift is calculated using a coefficient matrix to achieve dual-parameter measurement of magnetic field and temperature; the expression for the coefficient matrix is ​​as follows:

[0082]

[0083] Where ΔT is the change in external temperature; ΔH is the change in external magnetic field strength; S MZI1-T The temperature sensitivity of the first MZI; S MZI2-T The temperature sensitivity of the second MZI; S MZI1-H The magnetic field sensitivity of the first MZI; S MZI2-H The magnetic field sensitivity of the second MZI; Δλ MZI1 Δλ represents the wavelength shift of the first MZI. MZI2 This is the second MZI wavelength shift.

[0084] The interference spectrum of the first MZI is as follows Figure 4 As shown in (a), the interference spectrum of the second MZI is as follows: Figure 4 As shown in (b), the interference spectrum of the sensor, which is also the interference spectrum corresponding to the coupled beam, is as follows: Figure 4 As shown in (c).

[0085] Both the first and second MZIs are sensitive to temperature changes. For the first MZI, the refractive index of the magnetofluid in the magnetofluid cavity increases with increasing temperature, leading to Δn eff1 The refractive index decreases, resulting in a blue shift in the interference spectrum of the first MZI. For the second MZI, the refractive index of the UV film increases with increasing temperature, leading to an increase in the effective refractive index of the second cladding layer, Δn. eff2 The temperature rises, causing a redshift in the interference spectrum of the second MZI. The response of the sensor's interference spectrum to changes in external temperature is as follows: Figure 5 As shown.

[0086] When the external magnetic field strength changes, the first MZI is sensitive to the change in magnetic field strength, while the second MZI is unresponsive. For the first MZI, the refractive index of the magnetohydrodynamic cavity increases with increasing magnetic field strength, leading to Δn eff1 The decrease in Δn results in a blue shift in the interference spectrum of the first MZI. For the second MZI, its Δn... eff2 It does not change with the intensity of the external magnetic field and has no response to changes in the magnetic field. The response of the sensor's interference spectrum to changes in the intensity of the external magnetic field is as follows: Figure 6 As shown.

[0087] When both external temperature and magnetic field strength change simultaneously, dual-parameter measurement of magnetic field and temperature can be achieved using coefficient matrix demodulation, which can be expressed as:

[0088]

[0089] This application improves the integration of the sensor by using a cascaded MZI structure, enhances the detection sensitivity of the sensor by combining the magnetic sensitivity of the magnetohydrodynamic fluid and the temperature sensitivity of the UV film, and realizes dual-parameter measurement of the sensor by using coefficient matrix demodulation, thereby achieving high sensitivity and simultaneous measurement of magnetic field and temperature.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A fiber-optic magnetic field and temperature measurement device based on cascaded MZIs, characterized in that, The fiber magnetic field and temperature measurement device based on the cascaded MZI comprises an upper computer, a broadband light source, a sensor and a spectrum analyzer; The broadband light source is connected with the sensor; the sensor is connected with the spectrum analyzer; and the upper computer is connected with the spectrum analyzer; The sensor comprises a quartz tube and a first single-mode optical fiber, a first few-mode optical fiber, a magnetic fluid filled side-hole optical fiber, a UV glue film coated hollow core optical fiber, a second few-mode optical fiber and a second single-mode optical fiber which are sequentially fused; The magnetic fluid filled side-hole optical fiber comprises a core, a first cladding and a magnetic fluid cavity; the core and the magnetic fluid cavity constitute a first MZI; and the quartz tube is used for packaging the first MZI; The UV glue film coated hollow core optical fiber comprises a hollow core, a second cladding and a UV glue film; the hollow core and the second cladding constitute a second MZI; The first single-mode optical fiber is used for guiding the light beam emitted by the broadband light source into the first few-mode optical fiber; The first few-mode optical fiber is used for expanding the light beam and then guiding the light beam into the magnetic fluid filled side-hole optical fiber and the UV glue film coated hollow core optical fiber in sequence, and guiding the light beam into the second few-mode optical fiber through the first MZI and the second MZI; the second few-mode optical fiber is used for coupling the received light beam to obtain a coupled light beam; The second single-mode optical fiber is used for guiding the coupled light beam out of the spectrum analyzer; The spectrum analyzer is used for demodulating the coupled light beam to obtain a corresponding interference spectrum; The upper computer is used for calculating according to the interference spectrum by using a coefficient matrix to realize the dual-parameter measurement of the magnetic field and the temperature.

2. The fiber-optic magnetic field and temperature measurement device based on a cascade of MZIs according to claim 1, characterized in that, The fiber magnetic field and temperature measurement device based on the cascaded MZI further comprises an import single-mode optical fiber and an export single-mode optical fiber; The import single-mode optical fiber is connected with the broadband light source and the sensor respectively; and the export single-mode optical fiber is connected with the sensor and the spectrum analyzer respectively; The import single-mode optical fiber is used for transmitting the light beam emitted by the broadband light source to the sensor; The export single-mode optical fiber is used for transmitting the coupled light beam to the spectrum analyzer.

3. The fiber-optic magnetic field and temperature measurement device based on a concatenated MZI according to claim 1, characterized in that, The diameter of the core is 9 microns.

4. The fiber-optic magnetic field and temperature measurement device based on a concatenated MZI according to claim 1, characterized in that, The first cladding is internally provided with an air hole; the diameter of the air hole is 40 microns, and the outer diameter of the side-hole optical fiber is 125 microns.

5. The fiber-optic magnetic field and temperature measurement device based on a concatenated MZI according to claim 1, characterized in that, The inner diameter of the hollow core optical fiber is 10 microns, and the outer diameter is 125 microns.

6. The fiber-optic magnetic field and temperature measurement device based on a concatenated MZI according to claim 1, characterized in that, The length of the first few-mode optical fiber and the second few-mode optical fiber ranges from 500 microns to 1000 microns; the length of the magnetic fluid filled side-hole optical fiber ranges from 200 microns to 300 microns; and the length of the UV glue film coated hollow core optical fiber ranges from 600 microns to 700 microns.

7. The fiber-optic magnetic field and temperature measurement device based on a concatenated MZI according to claim 1, characterized in that, The thickness of the UV glue film ranges from 25 microns to 30 microns.

8. A method for fiber magnetic field and temperature measurement based on cascaded MZI, characterized in that, The fiber magnetic field and temperature measurement method based on the cascaded MZI is realized by using the fiber magnetic field and temperature measurement device based on the cascaded MZI in any one of claims 1 to 7; and the fiber magnetic field and temperature measurement method based on the cascaded MZI comprises The coupling light beam is obtained by expanding the light beam emitted by a broadband light source through a first few-mode optical fiber, introducing the light beam into a side-hole optical fiber filled with a magnetic fluid and a hollow-core optical fiber coated with a UV glue film, performing interference through a first MZI and a second MZI, and coupling the light beam through a second few-mode optical fiber; The coupling light beam is demodulated, and a coefficient matrix is used for calculation according to the demodulated interference spectrum, so as to realize dual-parameter measurement of the magnetic field and the temperature.

9. The fiber-optic magnetic field and temperature measurement method based on a concatenated MZI according to claim 8, wherein, The expression of an interference spectrum function corresponding to the first MZI is: The expression of an interference spectrum function corresponding to the second MZI is: The expression of an interference spectrum function corresponding to the coupling light beam obtained by coupling through the second few-mode optical fiber is: I sensor = I MZI1 · I MZI2 ; wherein, I MZI1 is the interference spectrum function corresponding to the first MZI; I1 is the light energy transmitted in the core of the side-hole fiber filled with magnetic fluid; I2 is the light energy transmitted in the magnetic fluid cavity; Δn eff1 is the effective refractive index difference of the core and the magnetic fluid cavity; L1 is the length of the side-hole fiber filled with magnetic fluid; λ is the wavelength of the incident light beam; I MZI2 is the interference spectrum function corresponding to the second MZI; I3 is the light energy transmitted in the hollow core; I4 is the light energy transmitted in the second cladding; Δn eff2 is the effective refractive index difference of the hollow core and the second cladding; L2 is the length of the UV glue film coated hollow core fiber; I sensor is the interference spectrum function corresponding to the coupling light beam; is the phase difference between the light beam transmitted in the core and the light beam transmitted in the magnetic fluid cavity in the first MZI; is the phase difference between the light beam transmitted in the hollow core and the light beam transmitted in the second cladding in the second MZI.

10. The fiber-optic magnetic field and temperature measurement method based on a concatenated MZI according to claim 9, wherein, The coupling light beam is demodulated, and a coefficient matrix is used for calculation according to the demodulated interference spectrum, so as to realize dual-parameter measurement of the magnetic field and the temperature, and specifically includes: The coupling light beam is demodulated based on an interference spectrum function corresponding to the coupling light beam, and an interference spectrum corresponding to the coupling light beam is determined; The wavelength drift amount is determined based on the interference spectrum; the wavelength drift amount includes a first MZI wavelength drift amount and a second MZI wavelength drift amount; The coefficient matrix is used for calculation according to the wavelength drift amount, so as to realize dual-parameter measurement of the magnetic field and the temperature; wherein the expression of the coefficient matrix is: wherein, ΔT is a change in external temperature; ΔH is a change in external magnetic field intensity; S MZI1-T is a temperature sensitivity of the first MZI; S MZI2-T is a temperature sensitivity of the second MZI; S MZI1-H is a magnetic field sensitivity of the first MZI; S MZI2-H is a magnetic field sensitivity of the second MZI; Δλ MZI1 is a wavelength shift of the first MZI; Δλ MZI2 is a wavelength shift of the second MZI.

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