A Michelson interferometer type cryogenic sensor with multi-core optical fiber cascade

Abstract

The present invention discloses a Michelson interference type low temperature sensor of multi-core optical fiber cascade, comprising: a packaging part and an optical fiber sensing module, the packaging part comprising a first sub-part and a second sub-part, the first sub-part being a cylindrical platform, the second sub-part being a cylindrical tube; in a first direction, the first sub-part comprises a first surface and a second surface arranged opposite to each other, and the second sub-part is connected to the second surface; the packaging part comprises a first opening, the first opening penetrates the cylindrical platform in the first direction and extends to the cylindrical tube, the optical fiber sensing module is located in the first opening, and the optical fiber sensing module comprises a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber. The present invention adopts a novel optical fiber Michelson interference structure, cascades a dual-core optical fiber and a seven-core optical fiber, not only making the structure of the optical fiber sensing module simple and easy to manufacture, but also enabling the optical fiber sensing module to have a higher low temperature sensitivity by adjusting the discharge intensity, discharge time, advancement distance and retraction distance during the fusion splicing process.

Description

Technical Field

[0001] The invention belongs to the technical field of low-temperature measurement, and in particular relates to a multi-core optical fiber cascade Michelson interference type low-temperature sensor. Background Art

[0002] Low temperature measurement has very important research significance in cutting-edge technology fields such as superconductivity and supercritical fluid high-energy physics, biology, military, and aerospace in the field of condensed matter physics. Technologies such as pulsed strong magnetic fields, energy, nuclear fusion, and space technology all work in extreme low-temperature environments. Therefore, structural health monitoring in these complex fields has put forward new requirements for temperature sensing technology.

[0003] At present, the low-temperature sensors in the relevant technology mainly include PLC (Programmable Logic Controller) type low-temperature sensors, MEMS (Micro-Electro-Mechanical System) type low-temperature sensors and thermocouple low-temperature sensors. However, traditional thermocouple low-temperature sensors are susceptible to electromagnetic interference, and the heat loss of thermocouple cables will also reduce the accuracy and reliability of temperature measurement. The structure and process of PLC and MEMS type low-temperature sensors are complex, the production cost is high, and they are limited in practical use. Compared with the above-mentioned types of sensors, optical fiber low-temperature sensors have the advantages of simple structure, small size, light weight, high sensitivity, fast response, high reliability and easy embedding inside the structure. They can work under strong electromagnetic interference and harsh environments, thus providing a new research idea for low-temperature measurement technology.

[0004] In the related art, the document "D. Sengupta et al, "An improved low-temperature sensing using PMMA coated FBG," in Proc. of SPIE-OSA-IEEE Asia Communications and Photonics., USA, 2011, pp. 8314-8317" achieves an extremely high temperature sensitivity of 8.97 nm / °C in the temperature range of -196.15°C to 29.85°C by coating polymethacrylate (PMMA) on the fiber grating. At the same time, the document "LT Li et al., "FFPI-FBG hybrid sensor to measure the thermal expansion and thermo-optical coefficient of a silica-based fiber at cryogenic temperatures," Chin. Opt. Lett., vol. 13, no. 10, pp. 100601, 2015" proposes a low-temperature sensor composed of a fiber grating and a Fabry-Perot interferometer, which can obtain a temperature sensitivity of 33.5 pm / °C in the temperature range of -243.15°C to -0.15°C. However, since most fiber Bragg grating low-temperature sensors need to be coated with temperature-sensitive materials or the sensors need to be metallized externally, the manufacturing process is complicated and the cost is high. In addition, fiber Bragg gratings are prone to multi-peak chirp when working at low temperatures, making it difficult to meet the needs of practical applications. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a multi-core optical fiber cascade Michelson interferometer low-temperature sensor. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] The embodiment of the present invention provides a multi-core optical fiber cascade Michelson interference type low temperature sensor, comprising: a packaging part and an optical fiber sensing module; wherein:

[0007] The packaging component includes a first sub-section and a second sub-section, the first sub-section is a cylindrical platform, and the second sub-section is a cylindrical tube; in a first direction, the first sub-section includes a first surface and a second surface arranged opposite to each other, the second sub-section is connected to the second surface, and the second sub-section extends along the first direction; the first direction is perpendicular to the plane where the cylindrical platform is located;

[0008] The packaging part includes a first opening, which passes through the cylindrical platform in a first direction and extends to the cylindrical tube. The optical fiber sensing module is located in the first opening, and the optical fiber sensing module includes a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber.

[0009] In one embodiment of the present invention, the second sub-section includes a first end and a second end arranged opposite to each other in its extension direction, and the first end is connected to the second surface;

[0010] Along the direction pointing from the first end to the second end, the optical fiber sensing module includes a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber that are sequentially fused together.

[0011] In one embodiment of the present invention, an optical fiber jumper is further included, one end of which is connected to the single-mode optical fiber.

[0012] In one embodiment of the present invention, in the first direction, the distance between the first surface of the cylindrical platform and the second end of the cylindrical tube is 80 mm, and the depth of the first opening is 70 mm.

[0013] In one embodiment of the present invention, the first opening penetrates the cylindrical platform and the cylindrical tube in a first direction.

[0014] In one embodiment of the present invention, a bolt is further included, and the second end of the second sub-part includes an internal thread, and the bolt is fixed in the first opening through the internal thread.

[0015] In one embodiment of the present invention, the packaging component includes LZ61 magnesium-lithium alloy material.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention provides a Michelson interference type low-temperature sensor with a multi-core optical fiber cascade, comprising: a packaging part and an optical fiber sensing module, wherein the packaging part comprises a first opening, the first opening penetrates a cylindrical platform in a first direction and extends to a cylindrical tube, the optical fiber sensing module is located in the first opening, the optical fiber sensing module comprises a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber, the present invention adopts a novel optical fiber Michelson interference structure, cascades a dual-core optical fiber and a seven-core optical fiber, not only making the structure of the optical fiber sensing module simple and easy to manufacture, but also by adjusting the discharge intensity, discharge time, advancement distance and retraction distance during the welding process, the optical fiber sensing module can have higher low-temperature sensitivity.

[0018] 2. The present invention utilizes packaging parts to seal the optical fiber sensor module, which can meet the packaging requirements of optical fiber sensor modules of different lengths without damaging its structure, and make the spectrum of the optical fiber sensor module consistent before and after packaging; in addition, since the packaging parts include the lightest material currently available, LZ61 magnesium-lithium alloy, it has the characteristics of low density, not easy to deform, easy to recycle, and excellent low-temperature impact performance, and is particularly suitable for low-temperature sensing.

[0019] 3. When the first opening penetrates the packaging part in the first direction, the second end of the second sub-part can realize the packaging of the reflective or transmissive low-temperature sensor by installing and removing bolts, thereby overcoming the disadvantage of processing a variety of packaging parts to meet the measurement requirements of different types of sensors.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural schematic diagram of a multi-core optical fiber cascade Michelson interferometer type low-temperature sensor provided by an embodiment of the present invention;

[0022] Figure 2 is a structural schematic diagram of an optical fiber sensing module provided by an embodiment of the present invention;

[0023] Figure 3 This is an example diagram of a single-mode-dual-core-seven-core optical fiber after fusion splicing provided in this embodiment;

[0024] Figure 4 is an example diagram of the end face of the seven-core optical fiber provided in this embodiment;

[0025] Figure 5 1 is another structural schematic diagram of a multi-core optical fiber cascade Michelson interference type low-temperature sensor provided by an embodiment of the present invention;

[0026] Figure 6 1 is another structural schematic diagram of a multi-core optical fiber cascade Michelson interference type low-temperature sensor provided by an embodiment of the present invention;

[0027] Figure 7 It is a structural schematic diagram of the internal thread of the packaging part provided by an embodiment of the present invention;

[0028] Figure 8 It is a structural schematic diagram of a bolt provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0030] Figure 11 is a schematic structural diagram of a multi-core optical fiber cascade Michelson interferometer cryogenic sensor provided by an embodiment of the present invention. Figure 2 FIG. 1 is a schematic diagram of a structure of an optical fiber sensor module provided by an embodiment of the present invention. Figure 1-2 The embodiment of the present invention provides a multi-core optical fiber cascade Michelson interference type low temperature sensor 1, comprising: a packaging part 10 and an optical fiber sensing module 20; wherein,

[0031] The packaging component 10 includes a first sub-section 101 and a second sub-section 102. The first sub-section 101 is a cylindrical platform, and the second sub-section 102 is a cylindrical tube. In a first direction, the first sub-section 101 includes a first surface and a second surface that are oppositely arranged, and the second sub-section 102 is connected to the second surface, and the second sub-section 102 extends along the first direction. The first direction is perpendicular to the plane where the cylindrical platform is located.

[0032] The packaging part 10 includes a first opening 103, which passes through the cylindrical platform in a first direction and extends to the cylindrical tube. The optical fiber sensor module 20 is located in the first opening 103. The optical fiber sensor module 20 includes SMF (Single Mode Fiber), DCF (Dual core fiber) and SCF (Seven Core Fiber).

[0033] Specifically, the multi-core optical fiber cascaded Michelson interferometer cryogenic sensor 1 provided in this embodiment may include a packaging part 10 and an optical fiber sensing module 20; wherein the packaging part 10 is in a "T" shape, and is composed of a first sub-part 101 and a second sub-part 102, and optionally, the first sub-part 101 is a cylindrical platform, and the second sub-part 102 is a cylindrical tube, and in a first direction, the cylindrical platform includes a first surface and a second surface that are arranged oppositely, and the cylindrical tube is connected to the second surface. In this embodiment, the first direction refers to a direction perpendicular to the plane where the cylindrical platform is located.

[0034] Furthermore, the packaging component 10 also includes a first opening 103, which passes through the above-mentioned cylindrical platform in a first direction and extends to the cylindrical tube. In this embodiment, the optical fiber sensing module 20 is sealed in the packaging component 10. When the external ambient temperature changes, the thermo-optical effect and thermal expansion effect of the optical fiber material will cause the change of the refractive index and length of the optical fiber, thereby causing the interference spectrum of the optical fiber sensing module 20 to drift. After demodulating the interference spectrum using the phase demodulation method, online real-time measurement of the external ambient temperature can be achieved.

[0035] It should be understood that the optical fiber sensing module 20 includes single-mode optical fiber, dual-core optical fiber and seven-core optical fiber. Compared with the traditional single-mode optical fiber, the optical fiber used in the embodiment of the present invention, especially the unique interference effect inside the multi-core optical fiber therein, can improve the low-temperature sensitivity of the optical fiber sensing module 20 and eliminate the chirp effect at low temperatures. At the same time, the larger core spacing of the seven-core optical fiber can effectively avoid spatial crosstalk between the cores, ensure seven-core single-mode transmission, and can also match well with the mode field of the traditional single-mode optical fiber.

[0036] like Figure 1-2 As shown, the second sub-portion 102 includes a first end and a second end that are arranged opposite to each other in its extension direction, and the first end is connected to the second surface;

[0037] Along the direction from the first end to the second end, the optical fiber sensing module 20 includes a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber which are sequentially fused.

[0038] In this embodiment, the second subsection 102 includes a first end and a second end, the first end is connected to the second surface of the cylindrical platform, and in the direction from the first end to the second end, the single-mode optical fiber, the dual-core optical fiber and the seven-core optical fiber are fused in sequence. Exemplarily, the cascade of single-mode-dual-core-seven-core optical fibers is performed according to the following steps:

[0039] First, use a fiber cleaver to cut the end faces of the single-mode fiber and the dual-core fiber flat, and wipe the surface of the single-mode fiber and the dual-core fiber with alcohol cotton; then, fix the single-mode fiber and the dual-core fiber to the left and right electrodes of the fiber fusion splicer respectively, set the core fusion splicing program, and the fusion splicing parameters that need to be set include: alignment mode is core fusion splicing, discharge intensity is 100bit, discharge time is 3000ms, advancement distance is 17μm, retraction distance is 0μm, and end face spacing is 20μm. After the fusion is completed, the parameters of the discharge inspection process include: core offset 0.25μm, cutting angle is 2.0deg, and left and right mode field radius is 25μm.

[0040] In addition, since the fusion splicing between the dual-core optical fiber and the seven-core optical fiber is similar to the above process, it will not be repeated here.

[0041] Figure 3 This is an example diagram of a single-mode-dual-core-seven-core optical fiber after fusion splicing provided in this embodiment. Figure 4 is an example diagram of the end face of the seven-core optical fiber provided in this embodiment. Figure 3From the perspective shown, it can be seen from the end face cutting of the rightmost seven-core optical fiber that the end face of the seven-core optical fiber after cutting is very flat, which is conducive to ensuring a certain reflectivity and providing conditions for mode interference in the optical fiber sensing module 20. In addition, during each cutting, the distance from the cutter position to the optical fiber melting point can be controlled according to actual measurement needs, and different lengths of dual-core or seven-core optical fibers can be adjusted to obtain different types of low-temperature sensors 1, thereby realizing real-time detection of temperature signals of the low-temperature sensor 1.

[0042] Figure 5 FIG. 1 is another structural schematic diagram of a multi-core optical fiber cascade Michelson interferometer type low-temperature sensor provided by an embodiment of the present invention. Figure 5 As shown, the multi-core optical fiber cascaded Michelson interference type low-temperature sensor 1 further includes an optical fiber jumper 30, one end of which is connected to the single-mode optical fiber.

[0043] Specifically, the working principle of the optical fiber sensor module 20 is as follows:

[0044] When the incident light propagates through the core of the single-mode fiber to the dual-core fiber part between the single-mode fiber and the seven-core fiber, part of the incident light still propagates in the core, and the other part of the incident light is coupled to the cladding of the dual-core fiber. When the two parts of light reach the transition area between the dual-core fiber and the seven-core fiber, due to the core mismatch, the high-order cladding mode will be excited again. The core mode and the excited cladding mode in the seven-core fiber will undergo Fresnel reflection on its right end face and propagate in the seven-core fiber and then return along the original path. When passing through the connection area between the single-mode fiber and the dual-core fiber again, due to the difference in optical path and effective refractive index, the excited high-order cladding mode interferes with the core mode and propagates at the core of the single-mode fiber, forming a fiber Michelson interferometer.

[0045] The interference intensity between the core mode and the cladding mode is:

[0046]

[0047] Where m = 0, ±1, ±2, ..., I core and are the light intensities of the core mode and the m-th order cladding mode, represents the phase difference between the core mode and the m-th order cladding mode, and R represents the reflectivity of the right end face of the seven-core fiber:

[0048]

[0049] Among them, n core and n s represent the refractive index of the fiber core and the surrounding medium, respectively.

[0050] The phase difference between the core mode and the m-order cladding mode can be expressed as:

[0051]

[0052] Among them, Δn eff represents the effective refractive index difference between the core mode and the main cladding mode, L represents the length of the seven-core fiber, and λ represents the wavelength of the incident light in vacuum.

[0053] When the phase difference satisfies When (k=0,±1,±2,…), the interference intensity is minimum, and the interference valley wavelength is:

[0054]

[0055] exist Figure 1 At the viewing angle shown, for the contact position between the upper surface of the optical fiber sensor module 20 and the protective cover of the optical fiber jumper 30, when the temperature inside the cryostat changes, due to the thermal expansion effect and the thermo-optical effect, the length and refractive index of the optical fiber will change as the external ambient temperature increases or decreases. From formula (3), it can be seen that the phase difference between the core fundamental mode and the m-order cladding mode will change, and the wavelength will drift accordingly.

[0056] The change rate of the interference valley wavelength drift in the interference spectrum with temperature, that is, the temperature sensitivity can be expressed as:

[0057]

[0058] It can be seen from the above formulas (4) and (5) that the temperature sensitivity of the optical fiber sensor module 20 is determined by the change of the refractive index with temperature and the expansion deformation of the optical fiber length with temperature.

[0059] Exemplarily, the core and cladding diameters of a single-mode optical fiber are 9.1 and 125 μm respectively, the central core and eccentric core diameters of a dual-core optical fiber are 5.5 μm and 8.5 μm respectively, the distance between the two is 36.5 μm, the cladding diameter is 125 μm, and the seven cores and cladding diameters of a seven-core optical fiber are 8 and 150 μm respectively, and the distance between the seven cores is 41.5 μm.

[0060] For example, since the outer diameter of the protective cover of the optical fiber jumper 30 is 11 mm, the diameter of the first opening 103 in this embodiment can be 11-12 mm. This design is not only convenient for packaging, but also only requires a small amount of low-temperature glue to achieve the sealing of the optical fiber sensor module 20. At the same time, the low-temperature glue will not flow into the first opening 103, thereby preventing it from affecting the internal structure of the optical fiber sensor module 20 and the packaging part 10.

[0061] Please continue to see Figure 1 or Figure 3In the first direction, the distance between the first surface of the cylindrical platform and the second end of the cylindrical tube is 80 mm, and the depth of the first opening 103 is 70 mm.

[0062] In this embodiment, the distance between the first surface of the cylindrical platform and the second end of the cylindrical tube is 80 mm, and the depth of the first opening 103 is 70 mm. Figure 1 or Figure 3 From the perspective shown, the portion of the packaging component 10 from the upper surface of the cylindrical platform to 70 mm downward is hollow, and the remaining 10 mm portion is solid. This design eliminates the need to use sealing glue to seal the optical fiber temperature sensor module, which helps to simplify the manufacturing process of the above-mentioned low-temperature sensor.

[0063] It should be noted that in this embodiment, the cylindrical platform and the cylindrical tube are integrally formed, and the outer diameter of the cylindrical tube may be 10 mm, which is conducive to the conduction and measurement of the external temperature and further improves the accuracy of the above-mentioned low-temperature sensor.

[0064] Figure 6 1 is another structural schematic diagram of a multi-core optical fiber cascaded Michelson interferometer cryogenic sensor provided by an embodiment of the present invention. In the multi-core optical fiber cascaded Michelson interferometer cryogenic sensor 1, the first opening 103 penetrates the cylindrical platform and the cylindrical tube in the first direction. This design method can reduce the difficulty of the process.

[0065] Optionally, the low temperature sensor 1 further includes a bolt 40 , and the second end of the second sub-section 102 includes an internal thread, and the bolt 40 is fixed in the first opening 103 via the internal thread.

[0066] Figure 7 is a schematic structural diagram of an internal thread of a packaging component provided by an embodiment of the present invention, Figure 8 Schematic diagram of a bolt structure provided by an embodiment of the present invention. Specifically, Figure 6 and Figure 1 The difference of the packaged component 10 shown is that Figure 6 An internal thread with a pitch of 3.5 mm is designed at a position 10 mm away from the bottom end of the cylindrical tube. Figure 7-8 As shown, the bolt 40 is tightly connected to meet the measurement requirements of the reflective Michelson interferometer optical fiber low temperature sensor. It should be understood that this design has a certain flexibility. By removing and installing the bolt 40, both the reflective sensor structure and the transmission sensor structure can be measured, which enhances the practicality and utilization of the packaged component 10.

[0067] Furthermore, the bolt 40 in the packaged part 10 has a specification of M 36, a coarse thread of 60°, a pitch of 4 mm, a thickness of 0.8 mm, a diagonal width of 55 mm, a head width of 22.5 mm, a standard hexagonal bolt 40 with a maximum outer diameter of 65 mm and a minimum outer diameter of 35 mm.

[0068] Optionally, the packaged component 10 includes LZ61 magnesium-lithium alloy material.

[0069] In this embodiment, the packaging part 10 is made of LZ61 magnesium-lithium alloy material, which has the advantages of light texture, high strength, good thermal and electrical conductivity, easy cutting and processing, and easy recycling. At the same time, the magnesium-lithium alloy has good electromagnetic shielding and shock absorption properties. Therefore, using magnesium-lithium alloy as the material of the packaging part 10 is more conducive to the sensing of external temperature, thereby improving the temperature detection accuracy.

[0070] It can be seen from the above embodiments that the beneficial effects of the present invention are:

[0071] 1. The present invention provides a Michelson interference type low-temperature sensor with a multi-core optical fiber cascade, comprising: a packaging part and an optical fiber sensing module, wherein the packaging part comprises a first opening, the first opening penetrates a cylindrical platform in a first direction and extends to a cylindrical tube, the optical fiber sensing module is located in the first opening, the optical fiber sensing module comprises a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber, the present invention adopts a novel optical fiber Michelson interference structure, cascades a dual-core optical fiber and a seven-core optical fiber, not only making the structure of the optical fiber sensing module simple and easy to manufacture, but also by adjusting the discharge intensity, discharge time, advancement distance and retraction distance during the welding process, the optical fiber sensing module can have higher low-temperature sensitivity.

[0072] 2. The present invention utilizes packaging parts to seal the optical fiber sensor module, which can meet the packaging requirements of optical fiber sensor modules of different lengths without damaging its structure, and make the spectrum of the optical fiber sensor module consistent before and after packaging; in addition, since the packaging parts include the lightest material currently available, LZ61 magnesium-lithium alloy, it has the characteristics of low density, not easy to deform, easy to recycle, and excellent low-temperature impact performance, and is particularly suitable for low-temperature sensing.

[0073] 3. When the first opening penetrates the packaging part in the first direction, the second end of the second sub-part can realize the packaging of the reflective or transmissive low-temperature sensor by installing and removing bolts, thereby overcoming the disadvantage of processing a variety of packaging parts to meet the measurement requirements of different types of sensors.

[0074] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0075] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0076] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0078] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0079] Although the present application is described herein in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in a claim. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0080] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A multi-core optical fiber cascade Michelson interferometer low-temperature sensor, characterized in that: include: Packaging parts and optical fiber sensing modules; wherein, The packaging component includes a first sub-section and a second sub-section, the first sub-section is a cylindrical platform, and the second sub-section is a cylindrical tube; in a first direction, the first sub-section includes a first surface and a second surface arranged opposite to each other, the second sub-section is connected to the second surface, and the second sub-section extends along the first direction; the first direction is perpendicular to the plane where the cylindrical platform is located; The packaging component includes a first opening, the first opening passes through the cylindrical platform in a first direction and extends to the cylindrical tube, the optical fiber sensing module is located in the first opening, and the optical fiber sensing module includes a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber; The second sub-section includes a first end and a second end which are arranged opposite to each other in the extension direction thereof, and the first end is connected to the second surface; Along the direction pointing from the first end to the second end, the optical fiber sensing module includes a single-mode optical fiber, a dual-core optical fiber and a seven-core optical fiber which are sequentially fused.

2. The multi-core optical fiber cascade Michelson interferometer low-temperature sensor according to claim 1, characterized in that: It also includes an optical fiber jumper, one end of which is connected to the single-mode optical fiber.

3. The multi-core optical fiber cascade Michelson interferometer low-temperature sensor according to claim 1, characterized in that: In the first direction, the distance between the first surface of the cylindrical platform and the second end of the cylindrical tube is 80 mm, and the depth of the first opening is 70 mm.

4. The multi-core optical fiber cascade Michelson interferometer low-temperature sensor according to claim 3, characterized in that: The first opening penetrates the cylindrical platform and the cylindrical tube in a first direction.

5. The multi-core optical fiber cascade Michelson interferometer low-temperature sensor according to claim 4, characterized in that: A bolt is also included. The second end of the second sub-part includes an internal thread. The bolt is fixed in the first opening through the internal thread.

6. The multi-core optical fiber cascade Michelson interferometer low-temperature sensor according to claim 1, characterized in that: The packaging parts include LZ61 magnesium-lithium alloy material.

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