Cascade MZI-based optical fiber magnetic field and temperature measuring device and method

Abstract

The invention discloses a cascaded MZI-based optical fiber magnetic field and temperature measurement device and method, 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 fiber, a first few-mode fiber, a magnetofluid-filled side hole fiber, a UV adhesive film-coated hollow fiber, a second few-mode fiber and a second single-mode fiber which are welded in sequence, the fiber core in the side hole optical fiber filled with the magnetic fluid and the magnetic fluid cavity form a first MZI; a hollow fiber core in the hollow optical fiber coated with the UV adhesive film and a second cladding form a second MZI; after the first few-mode optical fiber expands a light beam introduced by the first single-mode optical fiber, the light beam is introduced into the second few-mode optical fiber through the first MZI and the second MZI for coupling, the coupled light beam is demodulated, and a coefficient matrix is adopted for calculation, so that double-parameter measurement of the magnetic field and the temperature is achieved. The invention aims to realize simultaneous detection of double parameters of the magnetic field and the temperature, and is high in sensitivity.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensing technology, and in particular to an optical fiber magnetic field and temperature measurement device and method based on cascaded MZI. Background Art

[0002] As important characterization parameters in industrial production, scientific research and daily life, accurate measurement of magnetic field and temperature is crucial for biomedicine, aerospace, power system and other fields. Fiber optic sensors have attracted widespread attention from researchers due to their corrosion resistance, anti-electromagnetic interference and ability to realize remote multi-parameter detection, and have made up for the shortcomings of traditional sensors in many application fields. Various fiber optic sensors based on fiber interferometer mechanisms have been proposed and applied to the measurement of magnetic field and temperature. The currently known technology is to achieve the measurement of temperature and magnetic field by dislocation welding a multimode optical fiber in the middle of two single-mode optical fibers and cascading fiber Bragg gratings. And by encapsulating two single-mode optical fibers in a quartz tube to prepare a Fabry-Perot cavity, and by cascading fiber Bragg gratings attached to the surface of the strain gauge to achieve the measurement of temperature and magnetic field. However, all of the above technologies require the use of fiber Bragg gratings to achieve the measurement of magnetic field and temperature, which increases the cost, and also has problems such as low sensitivity and poor mechanical stress of asymmetric structures. Summary of the invention

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

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

[0005] In a first aspect, the present application provides an optical fiber magnetic field and temperature measurement device based on a cascaded MZI, comprising: a host computer, a broadband light source, a sensor, and a spectrum analyzer;

[0006] The broadband light source is connected to the sensor; the sensor is connected to the spectrum analyzer; the host computer is connected to the spectrum analyzer;

[0007] The sensor comprises a quartz tube and a first single-mode optical fiber, a first few-mode optical fiber, a side-hole optical fiber filled with magnetic fluid, a hollow-core optical fiber coated with UV adhesive film, a second few-mode optical fiber, and a second single-mode optical fiber which are fused in sequence;

[0008] The side hole optical fiber filled with magnetic fluid comprises 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 hollow core optical fiber coated with UV adhesive film comprises a hollow core, a second cladding and a UV adhesive film; the hollow core and the second cladding constitute a second MZI;

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

[0011] The first few-mode optical fiber is used to expand the light beam, and then sequentially introduce the light beam into the side-hole optical fiber filled with magnetic fluid and the hollow-core optical fiber coated with UV adhesive film, and then introduce 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 to couple the received light beam to obtain a coupled light beam;

[0012] The second single-mode optical fiber is used to guide the coupled light beam to the optical spectrum analyzer;

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

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

[0015] Optionally, the optical fiber magnetic field and temperature measurement device based on cascaded MZI further comprises: an import single-mode optical fiber and an export single-mode optical fiber;

[0016] The import single-mode optical fiber is connected to the broadband light source and the sensor respectively; the export single-mode optical fiber is connected to the sensor and the spectrum analyzer respectively;

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

[0018] The output single-mode optical fiber is used to transmit the coupled light beam to the optical spectrum analyzer.

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

[0020] Optionally, an air hole is opened inside the first cladding; the diameter of the air hole is 40 microns, and the outer diameter of the side hole optical fiber is 125 microns.

[0021] Optionally, the inner diameter of the hollow core optical fiber is 10 microns and the outer diameter is 125 microns.

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

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

[0024] In a second aspect, the present application provides a method for measuring an optical fiber magnetic field and temperature based on a cascaded MZI, wherein the method for measuring an optical fiber magnetic field and temperature based on a cascaded MZI is implemented by the optical fiber magnetic field and temperature measuring device based on a cascaded MZI as described above; the method for measuring an optical fiber magnetic field and temperature based on a cascaded MZI comprises:

[0025] Acquire a coupled light beam; the coupled light beam is obtained by expanding the light beam emitted by the broadband light source through the first few-mode optical fiber, introducing the light beam into the side hole optical fiber filled with magnetic fluid and the hollow core optical fiber coated with UV adhesive film, interfering with the first MZI and the second MZI, and then coupling with the second few-mode optical fiber;

[0026] The coupled light beam is demodulated, and a coefficient matrix is ​​used to perform calculations based on the interference spectrum obtained by demodulation, so as to realize dual parameter measurement of magnetic field and temperature.

[0027] Optionally, the expression of the interference spectrum function corresponding to the first MZI is:

[0028]

[0029] The expression of the interference spectrum function corresponding to the second MZI is:

[0030]

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

[0032] I sensor =I MZI1 I MZI2 ;

[0033] Among them, 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 optical fiber filled with magnetic fluid; I2 is the light energy transmitted in the magnetic fluid cavity; Δn eff1 is the effective refractive index difference between the fiber 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 between the hollow core fiber and the second cladding; l2 is the length of the hollow core fiber coated with UV adhesive film; I sensor is the interference spectrum function corresponding to the coupled beam; is the phase difference between the light beam transmitted by the fiber 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.

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

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

[0036] Determine a wavelength drift based on the interference spectrum; the wavelength drift includes: a first MZI wavelength drift and a second MZI wavelength drift;

[0037] The coefficient matrix is ​​used to calculate according to the wavelength drift to realize the dual parameter measurement of magnetic field and temperature; wherein the expression of the coefficient matrix is:

[0038]

[0039] Among them, ΔT is the change of external temperature; ΔH is the change of external magnetic field intensity; S MZI1-T is the temperature sensitivity of the first MZI; S MZI2-T is the temperature sensitivity of the second MZI; S MZI1-H is the magnetic field sensitivity of the first MZI; S MZI2-H is the magnetic field sensitivity of the second MZI; Δλ MZI1 is the wavelength drift of the first MZI; Δλ MZI2 is the wavelength drift of the second MZI.

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

[0041] The present application provides an optical fiber magnetic field and temperature measurement device and method based on cascaded MZI, the device comprising: a broadband light source, a sensor and a spectrum analyzer; the sensor comprising a quartz tube and a first single-mode optical fiber, a first few-mode optical fiber, a side-hole optical fiber filled with magnetic fluid, a hollow-core optical fiber coated with UV adhesive film, a second few-mode optical fiber, and a second single-mode optical fiber which are fused in sequence; the core and the magnetic fluid cavity in the side-hole optical fiber filled with magnetic fluid constitute the first MZI; the hollow-core optical fiber core and the second cladding in the hollow-core optical fiber coated with UV adhesive film constitute the second MZI; the first few-mode optical fiber expands the light beam introduced by the first single-mode optical fiber, and then introduces it into the second few-mode optical fiber through the first MZI and the second MZI for coupling, and uses the spectrum analyzer for demodulation, and then uses the coefficient matrix based on the host computer for calculation to realize the dual-parameter measurement of magnetic field and temperature. The present application improves the integration of the sensor through the cascaded MZI structure, combines the magnetic sensitivity of the magnetic fluid and the temperature sensitivity of the UV film to improve the detection sensitivity of the sensor, and uses coefficient matrix demodulation to realize the dual parameter measurement of the sensor, thereby realizing high sensitivity and simultaneous measurement of the magnetic field and temperature. In addition, the sensor provided by the present application has high sensitivity, high integration and stable structure. Therefore, the present application can realize the simultaneous detection of the dual parameters of the magnetic field and temperature with high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 Schematic diagram of the optical fiber magnetic field and temperature measurement device based on cascaded MZI provided in this application;

[0044] Figure 2 A schematic diagram of the structure of the sensor provided for this application;

[0045] Figure 3 A schematic cross-sectional view of an optical fiber provided in this application; wherein, Figure 3 (a) is a schematic diagram of a side-hole optical fiber filled with magnetic fluid. Figure 3 (b) is a schematic diagram of a hollow-core optical fiber coated with a UV adhesive film;

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

[0047] Figure 5 The response diagram of the spectrum of the sensor provided in this application as the external temperature changes;

[0048] Figure 6 This is a response diagram of the sensor spectrum provided in this application as the intensity of the external magnetic field changes.

[0049] Figure numerals: broadband light source-1; import single-mode optical fiber-2; sensor-3; export single-mode optical fiber-4; spectrum analyzer-5; host computer-6; first single-mode optical fiber-31; first few-mode optical fiber-32; side hole optical fiber-33; hollow core optical fiber-34; second few-mode optical fiber-35; second single-mode optical fiber-36; quartz tube-37; opening-38; magnetic fluid cavity-39; UV film-310. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0051] The existing optical fiber magnetic field and temperature sensors have low sensitivity, poor structural stability, and low accuracy in dual-parameter measurement. Based on the characteristics of magnetic fluid and UV film, the principle of optical fiber Mach-Zehnder interferometer (MZI), and the coefficient matrix demodulation mechanism, the present application proposes an optical fiber magnetic field and temperature sensor based on cascaded MZI. The optical fiber sensor has high sensitivity, high integration, and stable structure, and can achieve simultaneous measurement of magnetic field and temperature. That is, the present application achieves high sensitivity and dual-parameter simultaneous measurement of magnetic field and temperature by cascading MZI, combining magnetic fluid and UV film, and utilizing coefficient matrix demodulation. In addition, the sensor provided by the present application has a stable structure, high integration, and high sensitivity, and can achieve simultaneous detection of magnetic field and temperature.

[0052] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

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

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

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

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

[0057] The second single-mode optical fiber 36 is used to export the coupled light beam to the spectrum analyzer 5; the spectrum analyzer 5 is used to demodulate the coupled light beam to obtain the corresponding interference spectrum. The host computer 6 is used to calculate using the coefficient matrix according to the interference spectrum to achieve dual parameter measurement of magnetic field and temperature.

[0058] In one embodiment, the optical fiber magnetic field and temperature measurement device based on the cascaded MZI also includes: an import single-mode optical fiber 2 and an export single-mode optical fiber 4; the import single-mode optical fiber 2 is connected to the broadband light source 1 and the sensor 3 respectively; the export single-mode optical fiber 4 is connected to the sensor 3 and the spectrum analyzer 5 respectively.

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

[0060] That is, the light beam emitted by the broadband light source 1 is transmitted to the sensor 3 through the introduction single-mode optical fiber 2, the incident light beam is introduced into the first few-mode optical fiber 32 through the first single-mode optical fiber 31, and after being expanded by the first few-mode optical fiber 32, it is introduced into the second few-mode optical fiber 35 through the first MZI and the second MZI in sequence, and after being coupled by the second few-mode optical fiber 35, it is output by the second single-mode optical fiber 36, and the outgoing light beam is transmitted to the spectrum analyzer 5 through the output single-mode optical fiber 4.

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

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

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

[0064] As an optional embodiment, the diameter of the fiber core is 9 microns. An air hole is opened inside the first cladding; the diameter of the air hole is 40 microns, and the outer diameter of the side hole optical fiber is 125 microns. The inner diameter of the hollow core optical fiber is 10 microns, and the outer diameter is 125 microns. The length range of the first few-mode optical fiber and the second few-mode optical fiber is 500 microns-1000 microns; the length range of the side hole optical fiber filled with magnetic fluid is 200 microns-300 microns; the length range of the hollow core optical fiber coated with UV adhesive film is 600 microns-700 microns. The thickness range of the UV adhesive film is 25 microns-30 microns.

[0065] The core diameters of the first single-mode optical fiber and the second single-mode optical fiber are both in the range of 8 microns to 9 microns, and the outer diameters are both 125 microns; the core diameters of the first few-mode optical fiber and the second few-mode optical fiber are both 70 microns, and the outer diameters are both 125 microns;

[0066] The air hole of the side-hole optical fiber filled with magnetic fluid is provided with an opening on one side for filling the magnetic fluid, the opening diameter is 15 microns to 20 microns, and the density of the opening is 20 to 25 per millimeter; the inner diameter of the quartz tube is 125 microns and the outer diameter is 200 microns.

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

[0068] The first single-mode optical fiber, the first few-mode optical fiber, the side-hole optical fiber, the hollow-core optical fiber, the second few-mode optical fiber and the second single-mode optical fiber are sequentially fused; an opening is made on one side of the air hole of the side-hole optical fiber by using a femtosecond laser; a magnetic fluid is injected into the air hole of the side-hole optical fiber based on the opening to form a magnetic fluid cavity; the side-hole optical fiber filled with magnetic fluid is encapsulated by a quartz tube; the surface of the hollow-core optical fiber is coated with UV glue to form a UV glue film on the surface of the hollow-core optical fiber; after curing with a UV lamp, the preparation of the sensor is completed.

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

[0070] The coupled beam is obtained by expanding the beam emitted by the broadband light source through the first few-mode fiber, introducing it into the side-hole fiber filled with magnetic fluid and the hollow-core fiber coated with UV adhesive film, interfering with the first MZI and the second MZI, and then coupling it with 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 to achieve dual parameter measurement of magnetic field and temperature.

[0072] The expression of the interference spectrum function corresponding to the first MZI is:

[0073]

[0074] The expression of the interference spectrum function corresponding to the second MZI is:

[0075]

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

[0077] I sensor =I MZI1 I MZI2 .

[0078] Among them, I MZI1is the interference spectrum function corresponding to the first MZI; I1 is the light energy transmitted in the core of the side-hole optical fiber filled with magnetic fluid; I2 is the light energy transmitted in the magnetic fluid cavity; Δn eff1 is the effective refractive index difference between the fiber 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 between the hollow core and the second cladding; L2 is the length of the hollow core optical fiber coated with UV adhesive film; I sensor is the interference spectrum function corresponding to the coupled beam; is the phase difference between the light beam transmitted by the fiber 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.

[0079] In one embodiment, the coupled light beam is demodulated, and a coefficient matrix is ​​used to calculate the interference spectrum obtained by 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 coefficient matrix is ​​used to calculate according to the wavelength drift to realize the dual parameter measurement of magnetic field and temperature; wherein, the expression of the coefficient matrix is:

[0082]

[0083] Among them, ΔT is the change of external temperature; ΔH is the change of external magnetic field intensity; S MZI1-T is the temperature sensitivity of the first MZI; S MZI2-T is the temperature sensitivity of the second MZI; S MZI1-H is the magnetic field sensitivity of the first MZI; S MZI2-H is the magnetic field sensitivity of the second MZI; Δλ MZI1 is the wavelength drift of the first MZI; Δλ MZI2 is the wavelength drift of the second MZI.

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

[0085] When the external temperature changes, both the first MZI and the second MZI are sensitive to the temperature change. For the first MZI, the refractive index of the magnetic fluid in the magnetic fluid cavity increases with the increase of temperature, resulting in Δn eff1 As the temperature of the second MZI increases, the refractive index of the UV film increases, which leads to an increase in the effective refractive index of the second cladding, Δn eff2 The interference spectrum of the second MZI red shifts. The response of the interference spectrum of the sensor to the change of external temperature is shown in Figure 5 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 does not respond to the change in magnetic field strength. For the first MZI, the refractive index of the magnetic fluid in the magnetic fluid cavity increases with the increase in magnetic field strength, resulting in Δn eff1 The interference spectrum of the first MZI is blue-shifted. eff2 It does not change with the external magnetic field strength and has no response to the magnetic field changes. The response of the sensor's interference spectrum to the change of the external magnetic field strength is as follows: Figure 6 shown.

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

[0088]

[0089] The present application improves the integration of the sensor through a cascaded MZI structure, improves the detection sensitivity of the sensor by combining the magnetic sensitivity of the magnetic fluid and the temperature sensitivity of the UV film, and uses coefficient matrix demodulation to realize dual-parameter measurement of the sensor, thereby achieving high-sensitivity and simultaneous dual-parameter measurement of the magnetic field and temperature.

[0090] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, 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 article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. An optical fiber magnetic field and temperature measurement device based on cascaded MZI, characterized in that: The optical fiber magnetic field and temperature measurement device based on cascaded MZI includes: a host computer, a broadband light source, a sensor and a spectrum analyzer; The broadband light source is connected to the sensor; the sensor is connected to the spectrum analyzer; the host computer is connected to the spectrum analyzer; The sensor comprises a quartz tube and a first single-mode optical fiber, a first few-mode optical fiber, a side-hole optical fiber filled with magnetic fluid, a hollow-core optical fiber coated with UV adhesive film, a second few-mode optical fiber, and a second single-mode optical fiber which are fused in sequence; The side hole optical fiber filled with magnetic fluid comprises 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; The hollow core optical fiber coated with UV adhesive film comprises a hollow core, a second cladding and a UV adhesive film; the hollow core and the second cladding constitute a second MZI; The first single-mode optical fiber is used to guide the light beam emitted by the broadband light source into the first few-mode optical fiber; The first few-mode optical fiber is used to expand the light beam, and then sequentially introduce the light beam into the side-hole optical fiber filled with magnetic fluid and the hollow-core optical fiber coated with UV adhesive film, and then introduce 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 to couple the received light beam to obtain a coupled light beam; The second single-mode optical fiber is used to guide the coupled light beam to the optical spectrum analyzer; The spectrum analyzer is used to demodulate the coupled light beam to obtain a corresponding interference spectrum; The host computer is used to perform calculations using a coefficient matrix according to the interference spectrum to achieve dual parameter measurements of magnetic field and temperature.

2. The optical fiber magnetic field and temperature measurement device based on cascaded MZI according to claim 1, characterized in that: The optical fiber magnetic field and temperature measurement device based on cascaded MZI also includes: an import single-mode optical fiber and an export single-mode optical fiber; The import single-mode optical fiber is connected to the broadband light source and the sensor respectively; the export single-mode optical fiber is connected to the sensor and the spectrum analyzer respectively; The introduced single-mode optical fiber is used to transmit the light beam emitted by the broadband light source to the sensor; The output single-mode optical fiber is used to transmit the coupled light beam to the optical spectrum analyzer.

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

4. The optical fiber magnetic field and temperature measurement device based on cascaded MZI according to claim 1, characterized in that: An air hole is opened inside the first cladding; the diameter of the air hole is 40 microns, and the outer diameter of the side hole optical fiber is 125 microns.

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

6. The optical fiber magnetic field and temperature measurement device based on cascaded MZI according to claim 1, characterized in that: The length range of the first few-mode optical fiber and the second few-mode optical fiber is 500 microns to 1000 microns; the length range of the side-hole optical fiber filled with magnetic fluid is 200 microns to 300 microns; the length range of the hollow-core optical fiber coated with UV adhesive film is 600 microns to 700 microns.

7. The optical fiber magnetic field and temperature measurement device based on cascaded MZI according to claim 1, characterized in that: The thickness of the UV adhesive film ranges from 25 microns to 30 microns.

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

9. The optical fiber magnetic field and temperature measurement method based on cascaded MZI according to claim 8, characterized in that: The expression of the interference spectrum function corresponding to the first MZI is: The expression of the interference spectrum function corresponding to the second MZI is: The expression of the interference spectrum function of the coupled beam obtained by coupling with the second few-mode fiber is: I sensor =I MZI1 ·I MZI2 ; Among them, 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 optical fiber filled with magnetic fluid; I2 is the light energy transmitted in the magnetic fluid cavity; Δn eff1 is the effective refractive index difference between the fiber 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 between the hollow core and the second cladding; L2 is the length of the hollow core optical fiber coated with UV adhesive film; I sensor is the interference spectrum function corresponding to the coupled beam; is the phase difference between the light beam transmitted by the fiber 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 optical fiber magnetic field and temperature measurement method based on cascaded MZI according to claim 9, characterized in that: The coupled light beam is demodulated, and a coefficient matrix is ​​used to calculate according to the interference spectrum obtained by demodulation to achieve dual parameter measurement of magnetic field and temperature, specifically including: Based on the interference spectrum function corresponding to the coupled light beam, the coupled light beam is demodulated to determine the interference spectrum corresponding to the coupled light beam; Determine a wavelength drift based on the interference spectrum; the wavelength drift includes: a first MZI wavelength drift and a second MZI wavelength drift; The coefficient matrix is ​​used for calculation according to the wavelength drift to realize the dual parameter measurement of magnetic field and temperature; wherein the expression of the coefficient matrix is: Among them, ΔT is the change of external temperature; ΔH is the change of external magnetic field intensity; S MZI1-T is the temperature sensitivity of the first MZI; S MZI2-T is the temperature sensitivity of the second MZI; S MZI1-H is the magnetic field sensitivity of the first MZI; S MZI2-H is the magnetic field sensitivity of the second MZI; Δλ MZI1 is the wavelength drift of the first MZI; Δλ MZI2 is the wavelength drift of the second MZI.

Images