Extensible and easy-to-implement high-sensitivity strain sensor and manufacturing method thereof

Abstract

The invention belongs to the technical field of optical fiber sensing application, and particularly relates to an extensible and easy-to-implement high-sensitivity strain sensor and a manufacturing method thereof. The sensor is composed of a high-sensitivity strain Fabry-Perot interferometer and a low-sensitivity strain Fabry-Perot interferometer which are parallel to each other. The high-sensitivity interferometer is composed of a first single-mode optical fiber, a first hollow-core capillary tube and a first conical single-mode optical fiber, the interferometer with an interference cavity and a long cantilever beam structure is formed, the cavity length of the interference cavity is 86.28 microns, and the length of a long cantilever beam L is 1882.2 microns. The low-sensitivity interferometer is composed of a second single-mode optical fiber, a second hollow-core capillary tube and a second conical single-mode optical fiber, a cavity formed by the end face of the second single-mode optical fiber and the end face of the second conical single-mode optical fiber is a reference cavity, and the cavity length of the reference cavity is 93.38 microns. The strain sensor has the characteristics of high strain measurement sensitivity and low temperature crosstalk, and is low in cost and easy to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber optic sensing applications, and particularly relates to a scalable and easily implementable high-sensitivity strain sensor and a manufacturing method thereof. Background Art

[0002] As a core means for material property evaluation and structural health monitoring, strain sensing technology plays an irreplaceable role in high-precision fields such as intelligent healthcare, infrastructure security, and aerospace. Compared with traditional electrical strain sensors that rely on resistance changes, fiber optic strain sensors have become a research hotspot for next-generation sensing technologies due to their advantages of anti-electromagnetic interference, distributed measurement capabilities, resistance to harsh environments, and miniaturized integration. Among them, fiber optic sensors based on Fabry-Perot interferometers (FPIs) have shown unique application value in complex working condition monitoring due to their compact structure, low manufacturing cost, and low temperature sensitivity.

[0003] In the field of strain sensing, the key to the engineering implementation of the Vernier effect lies in precisely controlling the cavity length difference between two Fabry-Perot interferometers. Traditional methods usually rely on high-precision nanoscale etching processes or complex lithography techniques, resulting in difficult-to-guarantee cavity length uniformity, poor sensor consistency, and high manufacturing costs. In addition, the open cavity is vulnerable to environmental dust pollution, and the difference in thermal expansion coefficients between the two cavities will introduce temperature crosstalk problems, further limiting the practical application of the sensor. Currently, the application of the Vernier effect in Fabry-Perot interferometric strain sensors faces two major technical bottlenecks: one is that the precise matching of the free spectral ranges of the two cavities requires breakthroughs in sub-micron cavity length control accuracy, and the other is the cross-sensitivity problem caused by the non-uniform influence of environmental parameters (temperature, humidity) on the two cavities. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a scalable and easily implementable high-sensitivity strain sensor and a manufacturing method thereof. The strain sensor has high sensitivity for strain measurement, low temperature crosstalk characteristics, and is low in cost and easy to implement.

[0005] The technical solution adopted by the present invention is as follows: A scalable and easily implementable high-sensitivity strain sensor, which is composed of a high-sensitivity strain Fabry-Perot interferometer and a low-sensitivity strain Fabry-Perot interferometer connected in parallel by a 2×2 coupler.

[0006] The high-sensitivity strain Fabry-Perot interferometer is composed of a first single-mode optical fiber, a first hollow capillary, and a first tapered single-mode optical fiber. One end of the first hollow capillary is fusion-spliced to one end of the first single-mode optical fiber, and the other end is fusion-spliced to the end of the tapered section of the first tapered single-mode optical fiber. A part of the tapered section of the first tapered single-mode optical fiber after fusion splicing is located inside the first hollow capillary, forming a high-sensitivity strain Fabry-Perot interferometer with a long cantilever beam structure. The cavity formed by the first hollow capillary, the end face of the first single-mode optical fiber, and the end face of the first tapered single-mode optical fiber is the interference cavity.

[0007] The cavity length of the interference cavity is 86.18 - 86.38 μm. This cavity length is the distance between the end face of the first single-mode optical fiber and the end face of the first tapered single-mode optical fiber. The length of the long cantilever beam L is 1881.2 - 1883.2 μm (the long cantilever beam L is the distance from the end face of the first single-mode optical fiber on the left to the fusion point, that is, the length of the first hollow capillary after welding).

[0008] The low-sensitivity strain Fabry-Perot interferometer is composed of a second single-mode optical fiber, a second hollow capillary, and a second tapered single-mode optical fiber. One end of the second hollow capillary is fusion-spliced to one end of the second single-mode optical fiber, and the other side is fusion-spliced to the end face of the tapered section of the second tapered single-mode optical fiber. The end face of the second single-mode optical fiber and the end face of the tapered section of the second tapered single-mode optical fiber form a reference cavity. The cavity length of the reference cavity is 93.28 - 93.48 μm.

[0009] Furthermore, the cavity length of the interference cavity is 86.18 μm, and the length of the long cantilever beam L is 1881.2 μm; the cavity length of the reference cavity is 93.28 μm.

[0010] Furthermore, the cavity length of the interference cavity is 86.28 μm, and the length of the long cantilever beam L is 1882.2 μm; the cavity length of the reference cavity is 93.38 μm.

[0011] Furthermore, the cavity length of the interference cavity is 86.38 μm, and the length of the long cantilever beam L is 1883.2 μm; the cavity length of the reference cavity is 93.48 μm.

[0012] Furthermore, the inner diameters of the first hollow capillary and the second hollow capillary are preferably 100 nm.

[0013] A method for fabricating a scalable and easily implementable high-sensitivity strain sensor, the fabrication method comprising the following steps: Step 1: Set up the experimental equipment. Introduce the optical signal from the supercontinuum light source into the output end of the first single-mode optical fiber through an optical fiber circulator, and connect the reflected light to the spectral analyzer to monitor and record the interference spectrum.

[0014] Step 2: Place the first single-mode optical fiber with a flat end face into the optical fiber fusion splicer; take another first hollow capillary with a flat end face and place it into the optical fiber fusion splicer. Observe the interface of the optical fiber fusion splicer, and control the driving motor to make the two end faces of the first single-mode optical fiber and the first hollow capillary approach the discharge center of the fusion splicer. Set the discharge power to -10 and the discharge time to 300 ms, and perform discharge to fuse the first single-mode optical fiber and the first hollow capillary together to form the first hollow single-mode optical fiber.

[0015] Step 3: Take out the first hollow single-mode optical fiber in the optical fiber fusion splicer, and use a fiber cutter to cut off the excess first hollow capillary.

[0016] Step 4: Fix the single-mode optical fiber with the coating layer stripped in a commercial optical fiber melting and tapering system (Idealphotonics, IPCS-5000-SMT). Set the fiber clamping and pulling distance to 0 - 4 mm and 4 - 15 mm, the pulling speed to 0.07 mm / s and 1 mm / s, the hydrogen gas flow rate to 147 sccm, the heating width of the hydrogen torch to 8 mm, and the scanning distance of the torch to 2.4 mm. After setting the parameters, start the commercial optical fiber melting and tapering system to melt and taper the single-mode optical fiber into a tapered single-mode optical fiber. Use a fiber cutter to cut the tapered single-mode optical fiber into two sections from the middle. One section is the first tapered single-mode optical fiber, and the other section is the second tapered single-mode optical fiber.

[0017] Step 5: Insert the tapered section of the first tapered single-mode optical fiber in Step 4 into the first hollow capillary of the first hollow single-mode optical fiber in Step 3. Adjust the first tapered single-mode optical fiber through the left and right motors of the optical fiber fusion splicer to form an interference cavity with the end face of the first single-mode optical fiber and the first hollow capillary; align the discharge electrode of the optical fiber fusion splicer with the end face of the first hollow capillary, set the welding time to 1000 ms, and the welding power to -10 bit, and fuse the end of the first hollow capillary with the tapered section of the first tapered single-mode optical fiber together. Cut off the regions with a length of 15 cm on both the left and right sides of the interference cavity (5) to obtain a high-sensitivity strain Fabry-Perot interferometer with an interference cavity and a long cantilever beam structure.

[0018] Step 6: Replace the optical fiber circulator with a 2×2 coupler. One end of the 2×2 coupler is respectively connected to the supercontinuum light source and the spectrum analyzer, and the other end is respectively connected to the high-sensitivity strain Fabry-Perot interferometer in Step 5 and the output end of a second single-mode optical fiber with a flat end face.

[0019] Step 7: Place the second single-mode optical fiber into the optical fiber fusion splicer; take another second hollow capillary with a flat end face and place it into the optical fiber fusion splicer. Observe the interface of the optical fiber fusion splicer, and control the driving motor to make the two end faces of the second single-mode optical fiber and the second hollow capillary approach the discharge center of the fusion splicer. Set the discharge power to -10 and the discharge time to 300 ms, and perform discharge to fuse the second single-mode optical fiber and the second hollow capillary together to form a second hollow single-mode optical fiber.

[0020] Step 8: Take out the second hollow single-mode optical fiber in the optical fiber fusion splicer, and use a fiber cutter to cut off the redundant second hollow capillary.

[0021] Step 9: Insert the tapered section of the second tapered single-mode optical fiber in Step 4 into the second hollow capillary of the second hollow single-mode optical fiber in Step 8. Adjust the distance between the end face of the second tapered single-mode optical fiber and the end face of the second hollow single-mode optical fiber through the left and right motors of the optical fiber fusion splicer, and at the same time observe the spectral analyzer until an obvious cursor envelope spectrum appears. At this time, the end face of the second single-mode optical fiber and the end face of the tapered section of the second tapered single-mode optical fiber form a reference cavity; then place the discharge electrode of the optical fiber fusion splicer against the end face of the tapered section of the second tapered single-mode optical fiber, set the welding time to 1000 ms, and the welding power to -10 bit, and fuse the second hollow single-mode optical fiber and the second tapered single-mode optical fiber together; thus, a low-sensitivity strain Fabry-Perot sensor interferometer with a reference cavity is fabricated.

[0022] A highly sensitive strain sensor that is scalable and easy to implement is composed of a high-sensitivity strain Fabry-Perot interferometer and a low-sensitivity strain Fabry-Perot interferometer connected in parallel by a 2×2 coupler.

[0023] Advantages of the present invention: A low-cost and high-efficiency strain sensor based on the cursor effect and its manufacturing method are designed, which can effectively suppress temperature interference while achieving high-sensitivity strain measurement. When the high-sensitivity strain Fabry-Perot interferometer is connected in parallel with the low-sensitivity strain Fabry-Perot interferometer, the sensor exhibits an ultra-high strain sensitivity of 631.12 pm / με, which is 11.96 times higher than that of a single high-sensitivity strain Fabry-Perot interferometer; in the temperature range of 25–150 °C, the temperature sensitivity is 9.39 pm / °C, and the temperature cross-sensitivity is as low as 0.015 με / °C, significantly reducing the measurement error caused by temperature changes. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of the scalable and easy-to-implement highly sensitive strain sensor in Embodiment 1.

[0025] Figure 2 is a schematic structural diagram of the high-sensitivity strain Fabry-Perot sensor interferometer in Embodiment 1.

[0026] Figure 3 It is a schematic structural diagram of the low-sensitivity strain Fabry-Perot sensor interferometer in the first embodiment.

[0027] Figure 4 It is a schematic diagram of Step 1 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0028] Figure 5 It is a schematic diagram of Step 2 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0029] Figure 6 It is a schematic diagram of Step 3 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0030] Figure 7 It is a schematic diagram of Step 4 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0031] Figure 8 It is a schematic diagram of Step 5 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0032] Figure 9 It is a schematic diagram of Step 6 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0033] Figure 10 It is a schematic diagram of Step 7 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0034] Figure 11 It is a schematic diagram before fusion in Step 9 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0035] Figure 12 It is a schematic diagram after fusion in Step 9 of the fabrication method of the scalable and easily implementable high-sensitivity strain sensor in the fourth embodiment.

[0036] Figure 13 It is an interference curve spectrogram of the scalable and easily implementable high-sensitivity strain sensor after applying an axial stress of 0 - 200 με to the sensor in steps of 25 με.

[0037] Figure 14 It is an interference curve spectrogram of the scalable and easily implementable high-sensitivity strain sensor when the temperature is increased from 25 °C to 150 °C in steps of 25 °C.

[0038] Reference numerals: 1, high-sensitivity strain Fabry-Perot interferometer; 2, low-sensitivity strain Fabry-Perot interferometer; 3, 2×2 coupler; 4, optical fiber circulator; 5, optical spectrum analyzer; 6, optical fiber fusion splicer; 7, single-mode optical fiber; 8, commercial optical fiber fused taper system; 11, first single-mode optical fiber; 12, interference cavity; 13, first hollow capillary; 14, first tapered single-mode optical fiber; 21, second single-mode optical fiber; 22, reference cavity; 23, second hollow capillary; 24, second tapered single-mode optical fiber. Detailed implementation manners

[0039] Embodiment 1

[0040] As Figures 1-3 shown, a scalable and easily implementable high-sensitivity strain sensor is composed of a high-sensitivity strain Fabry-Perot interferometer 1 and a low-sensitivity strain Fabry-Perot interferometer 2 connected in parallel by a 2×2 coupler 3.

[0041] The high-sensitivity strain Fabry-Perot interferometer is composed of a first single-mode optical fiber 11, a first hollow capillary 13, and a first tapered single-mode optical fiber 14. One end of the first hollow capillary is fusion-spliced to one end of the first single-mode optical fiber, and the other end is fusion-spliced to the end of the tapered section of the first tapered single-mode optical fiber. A part of the tapered section of the fusion-spliced first tapered single-mode optical fiber is located inside the first hollow capillary, forming a high-sensitivity strain Fabry-Perot interferometer with a long cantilever beam structure. The cavity formed by the first hollow capillary, the end faces of the first single-mode optical fiber, and the end face of the first tapered single-mode optical fiber is the interference cavity 12. The cavity length of the interference cavity is 86.28 μm, and the length of the long cantilever beam L is 1882.2 μm.

[0042] The low-sensitivity strain Fabry-Perot interferometer is composed of a second single-mode optical fiber 21, a second hollow capillary 23, and a second tapered single-mode optical fiber 24. One end of the second hollow capillary is fusion-spliced to one end of the second single-mode optical fiber, and the other side is fusion-spliced to the end face of the tapered section of the second tapered single-mode optical fiber. The end face of the second single-mode optical fiber and the end face of the tapered section of the second tapered single-mode optical fiber form the reference cavity 22, and the cavity length of the reference cavity is 93.38 μm.

[0043] Embodiment 2 On the basis of the technical solution of Embodiment 1, the cavity length of the high-sensitivity strain Fabry-Perot interferometer and the length of the long cantilever beam are changed. The cavity length of the interference cavity is 86.18 μm, and the length of the long cantilever beam L is 1881.2 μm. The cavity length of the reference cavity of the low-sensitivity strain Fabry-Perot interferometer is changed, and the cavity length of the reference cavity is 93.28 μm.

[0044] Embodiment 3 On the basis of the technical solution of the first embodiment, the length of the dry cavity of the high-sensitivity strain Fabry-Perot interferometer and the length of the long cantilever beam are changed. The interference cavity length is 86.38 μm, and the length of the long cantilever beam L is 1883.2 μm. The length of the reference cavity of the low-sensitivity strain Fabry-Perot interferometer is changed, and the cavity length of the reference cavity is 93.48 μm.

[0045] Example 4 As Figures 4-12 shown, a method for manufacturing an extensible and easily implementable high-sensitivity strain sensor includes the following steps: Step 1: Set up the experimental equipment. Introduce the optical signal from the supercontinuum light source into the output end of the first single-mode optical fiber through an optical fiber circulator 4, and connect the reflected light to the optical spectrum analyzer 5 to monitor and record the interference spectrum.

[0046] Step 2: Place the first single-mode optical fiber with a flat end face in the optical fiber fusion splicer 6; take another first hollow capillary with a flat end face and place it in the optical fiber fusion splicer. Observe the interface of the optical fiber fusion splicer, and control the driving motor to make the two end faces of the first single-mode optical fiber and the first hollow capillary close to the discharge center of the fusion splicer. Set the discharge power to -10 and the discharge time to 300 ms, and perform discharge to fuse the first single-mode optical fiber and the first hollow capillary together to form the first hollow single-mode optical fiber.

[0047] Step 3: Take out the first hollow single-mode optical fiber in the optical fiber fusion splicer, and cut off the excess first hollow capillary with a fiber cutter.

[0048] Step 4: Fix the stripped single-mode optical fiber 7 in a commercial optical fiber fusion and tapering system 8 (Idealphotonics, IPCS-5000-SMT). Set the fiber clamp pulling distance to 0 - 4 mm and 4 - 15 mm, the pulling speed to 0.07 mm / s and 1 mm / s, the hydrogen gas flow rate to 147 sccm, the heating width of the hydrogen torch to 8 mm, and the torch scanning distance to 2.4 mm. After setting the parameters, start the commercial optical fiber fusion and tapering system to fuse and taper the single-mode optical fiber. Use an optical fiber cutter to cut the tapered single-mode optical fiber into two sections from the middle. One section is the first tapered single-mode optical fiber, and the other section is the second tapered single-mode optical fiber.

[0049] Step 5: Insert the tapered section of the first tapered single-mode fiber in Step 4 into the first hollow capillary of the first hollow single-mode fiber in Step 3. Adjust the first tapered single-mode fiber through the left and right motors of the optical fiber fusion splicer to form an interference cavity with the end face of the first single-mode fiber and the first hollow capillary. Align the discharge electrode of the optical fiber fusion splicer with the end face of the first hollow capillary, set the welding time to 1000 ms and the welding power to -10 bit, fuse the end of the first hollow capillary and the tapered section of the first tapered single-mode fiber together, and cut off the 15 cm length regions on both the left and right sides of the interference cavity to obtain a high-sensitivity strain Fabry-Perot interferometer with an interference cavity and a long cantilever beam structure.

[0050] Step 6: Replace the optical fiber circulator with a 2×2 coupler. Connect one end of the 2×2 coupler to the supercontinuum light source and the spectral analyzer respectively, and connect the other end to the high-sensitivity strain Fabry-Perot interferometer in Step 5 and the output end of a second single-mode fiber with a flat-cut end face respectively.

[0051] Step 7: Place the second single-mode fiber in the optical fiber fusion splicer; take another second hollow capillary with a flat-cut end face and place it in the optical fiber fusion splicer. Observe the interface of the optical fiber fusion splicer and control the drive motor to make the two end faces of the second single-mode fiber and the second hollow capillary close to the discharge center of the fusion splicer. Set the discharge power to -10 and the discharge time to 300 ms, and perform discharge to fuse the second single-mode fiber and the second hollow capillary together to make a second hollow single-mode fiber.

[0052] Step 8: Take out the second hollow single-mode fiber in the optical fiber fusion splicer and cut off the redundant second hollow capillary with a fiber cutter.

[0053] Step 9: Insert the tapered section of the second tapered single-mode fiber in Step 4 into the second hollow capillary of the second hollow single-mode fiber in Step 8. Adjust the distance between the end face of the second tapered single-mode fiber and the end face of the second hollow single-mode fiber through the left and right motors of the optical fiber fusion splicer, and at the same time observe the spectral analyzer until an obvious vernier envelope spectrum appears. At this time, a reference cavity is formed between the end face of the second single-mode fiber and the end face of the tapered section of the second tapered single-mode fiber. Then align the discharge electrode of the optical fiber fusion splicer with the end face of the tapered section of the second tapered single-mode fiber, set the welding time to 1000 ms and the welding power to -10 bit, and fuse the second hollow single-mode fiber and the second tapered single-mode fiber together; obtain a low-sensitivity strain Fabry-Perot sensor interferometer with a reference cavity.

[0054] A highly sensitive strain sensor that is scalable and easy to implement is composed of a high-sensitivity strain Fabry-Perot interferometer and a low-sensitivity strain Fabry-Perot interferometer connected in parallel by a 2×2 coupler. The high-sensitivity strain Fabry-Perot interferometer is formed by arc-discharging and fusing a single-mode fiber, a hollow capillary, and a tapered single-mode fiber to form a Fabry-Perot interferometer with a long cantilever beam structure. The low-sensitivity strain Fabry-Perot interferometer precisely matches the cavity length of the high-sensitivity strain Fabry-Perot interferometer by a fusion splicer to excite the Vernier effect. Applying the optical analog of the Vernier effect to a fiber interferometer is an effective means to improve the sensitivity and resolution of an optical sensor. The Vernier effect is achieved by obtaining two slightly detuned interference signals and overlapping them to generate a Vernier envelope, which shows amplified sensitivity compared to the individual interferometers that make up the structure. Since the cavity lengths of the sensing cavity and the reference cavity are close, the interference frequencies generated by the two interferometers are slightly offset. When the sensing cavity and the reference cavity are connected in parallel, the signals of the two overlap, resulting in an envelope modulation effect. Compared with using the sensing cavity alone, this structure can significantly amplify the sensitivity and improve the sensing performance of the sensor.

[0055] As Figure 13 shown, the change in the interference spectrum after applying an axial stress of 0 - 200 με to the air-cavity highly sensitive strain sensor based on the Vernier effect in steps of 25 με. Through the linear relationship between different stress levels and wavelengths and the fitting based on the wavelength drift and stress, the strain sensitivity of the fabricated sensor is obtained as 631.12 pm / με.

[0056] As Figure 14 shown, the temperature is increased from 25 °C to 150 °C in steps of 25 °C, and the interference spectrum at each temperature is collected. The temperature sensitivity of the air-cavity highly sensitive strain sensor based on the Vernier effect is 631.12 pm / με, and the temperature cross-sensitivity is 0.015 με / °C, having a low temperature sensitivity, thus reducing the measurement error caused by temperature changes, making it less affected by temperature when measuring strain in a complex environment and the data being more accurate.

[0057] To solve the problems of complex production process and high cost of fiber optic sensors with the cursor effect, a low-cost strain sensor based on a parallel Fabry-Perot interferometer is designed. The sensor adopts a minimalist structure design and consists of only single-mode fibers and hollow capillaries to form two parallel Fabry-Perot interferometers. The cavity length matching is achieved by a fusion splicer to realize the cursor effect. The sensor exhibits an ultra-high strain sensitivity of 631.12 pm / με and an ultra-low cross-sensitivity of 0.015 με / °C, greatly reducing the measurement error caused by temperature changes. The scalable and easily implementable high-sensitivity strain sensor combined with the optical cursor effect enables the sensor to significantly improve the sensitivity of stress measurement. Compared with the existing technology, the sensor only requires single-mode fibers, hollow capillaries and a commercial fusion splicer to produce a high-sensitivity strain sensor, which is simple to manufacture, easy to operate and has low cost.

Claims

1. A scalable and easily implementable highly sensitive strain sensor, characterized in that: The high-sensitivity strain sensor is composed of a high-sensitivity strain Fabry-Perot interferometer and a low-sensitivity strain Fabry-Perot interferometer connected in parallel by a 2×2 coupler; The high-sensitivity strain Fabry-Perot interferometer is composed of a first single-mode fiber, a first hollow capillary, and a first tapered single-mode fiber. One end of the first hollow capillary is fusion-spliced to one end of the first single-mode fiber, and the other end is fusion-spliced to the end of the tapered section of the first tapered single-mode fiber. Part of the tapered section of the first tapered single-mode fiber after fusion splicing is located inside the first hollow capillary, forming a high-sensitivity strain Fabry-Perot interferometer with a long cantilever beam structure. The cavity formed by the end faces of the first hollow capillary, the first single-mode fiber, and the first tapered single-mode fiber is the interference cavity; The cavity length of the interference cavity is 86.18 - 86.38 μm, and the length of the long cantilever beam L is 1881.2 - 1883.2 μm; The low-sensitivity strain Fabry-Perot interferometer is composed of a second single-mode fiber, a second hollow capillary, and a second tapered single-mode fiber. One end of the second hollow capillary is fusion-spliced to one end of the second single-mode fiber, and the other side is fusion-spliced to the end face of the tapered section of the second tapered single-mode fiber. The end face of the second single-mode fiber and the end face of the tapered section of the second tapered single-mode fiber form a reference cavity, and the cavity length of the reference cavity is 93.28 - 93.48 μm.

2. The scalable and easily implementable highly sensitive strain sensor according to claim 1, characterized in that: The cavity length of the interference cavity is 86.18 μm, and the length of the long cantilever beam L is 1881.2 μm; the cavity length of the reference cavity is 93.28 μm.

3. The scalable and easily implementable high-sensitivity strain sensor according to claim 1, characterized in that: The cavity length of the interference cavity is 86.28 μm, and the length of the long cantilever beam L is 1882.2 μm; the cavity length of the reference cavity is 93.38 μm.

4. The scalable and easily implementable high-sensitivity strain sensor according to claim 1, characterized in that: The cavity length of the interference cavity is 86.38 μm, and the length of the long cantilever beam L is 1883.2 μm; the cavity length of the reference cavity is 93.48 μm.

5. A method for fabricating an extensible and easily implementable highly sensitive strain sensor, characterized by: The manufacturing method includes the following steps: Step 1: Set up the experimental equipment. Introduce the optical signal from the supercontinuum light source into the output end of the first single-mode fiber through an optical fiber circulator, and connect the reflected light to the spectral analyzer to monitor and record the interference spectrum; Step 2: Place the first single-mode fiber with a flat end face in the optical fiber fusion splicer; take another first hollow capillary with a flat end face and place it in the optical fiber fusion splicer. Observe the interface of the optical fiber fusion splicer, and control the drive motor to make the two end faces of the first single-mode fiber and the first hollow capillary close to the discharge center of the fusion splicer. Set the discharge power to -10 and the discharge time to 300 ms, and perform discharge to fuse the first single-mode fiber and the first hollow capillary together to make the first hollow single-mode fiber; Step 3: Take out the first hollow single-mode fiber in the optical fiber fusion splicer, and cut off the excess first hollow capillary with a fiber cutter; Step 4: Fix the stripped single-mode optical fiber in a commercial fiber optic fusion tapering system. Set the fiber clamp pulling distance to 0 - 4 mm and 4 - 15 mm, the pulling speed to 0.07 mm / s and 1 mm / s, the hydrogen gas flow rate to 147 sccm, the heating width of the hydrogen torch to 8 mm, and the torch scanning distance to 2.4 mm. After setting the parameters, start the commercial fiber optic fusion tapering system to fuse and taper the single-mode optical fiber into a tapered single-mode optical fiber. Use a fiber optic cutter to cut the tapered single-mode optical fiber into two sections from the middle. One section is the first tapered single-mode optical fiber, and the other section is the second tapered single-mode optical fiber; Step 5: Insert the tapered section of the first tapered single-mode optical fiber in Step 4 into the first hollow capillary of the first hollow single-mode optical fiber in Step 3. Adjust the first tapered single-mode optical fiber through the left and right motors of the fiber optic fusion splicer to form an interference cavity with the end face of the first single-mode optical fiber and the first hollow capillary. Align the discharge electrode of the fiber optic fusion splicer with the end face of the first hollow capillary, set the welding time to 1000 ms, and the welding power to -10 bit. Fuse the end of the first hollow capillary and the tapered section of the first tapered single-mode optical fiber together to obtain a high-sensitivity strain Fabry - Perot interferometer with an interference cavity and a long cantilever beam structure; Step 6: Replace the fiber optic circulator with a 2 × 2 coupler. One end of the 2 × 2 coupler is connected to a supercontinuum light source and a spectral analyzer respectively, and the other end is connected to the high-sensitivity strain Fabry - Perot interferometer in Step 5 and the output end of a second single-mode optical fiber with a flat end face respectively; Step 7: Place the second single-mode optical fiber in the fiber optic fusion splicer. Take another second hollow capillary with a flat end face and place it in the fiber optic fusion splicer. Observe the interface of the fiber optic fusion splicer and control the driving motor to make the two end faces of the second single-mode optical fiber and the second hollow capillary close to the discharge center of the fusion splicer. Set the discharge power to -10 and the discharge time to 300 ms, and perform the discharge to fuse the second single-mode optical fiber and the second hollow capillary together to make a second hollow single-mode optical fiber; Step 8: Take out the second hollow single-mode optical fiber in the fiber optic fusion splicer and cut off the excess second hollow capillary with a fiber cutting knife; Step 9: Insert the tapered section of the second tapered single-mode optical fiber in Step 4 into the second hollow capillary of the second hollow single-mode optical fiber in Step 8. Adjust the distance between the end face of the second tapered single-mode optical fiber and the end face of the second hollow single-mode optical fiber through the left and right motors of the fiber optic fusion splicer, and at the same time observe the spectral analyzer until an obvious vernier envelope spectrum appears. At this time, the end face of the second single-mode optical fiber and the end face of the tapered section of the second tapered single-mode optical fiber form a reference cavity. Then align the discharge electrode of the fiber optic fusion splicer with the end face of the tapered section of the second tapered single-mode optical fiber, set the welding time to 1000 ms, and the welding power to -10 bit, and fuse the second hollow single-mode optical fiber and the second tapered single-mode optical fiber together; Obtain a low-sensitivity strain Fabry - Perot sensor interferometer with a reference cavity; A highly sensitive strain sensor that is scalable and easy to implement is composed of a high-sensitivity strain Fabry-Perot interferometer and a low-sensitivity strain Fabry-Perot interferometer connected in parallel by a 2×2 coupler.

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