Optical fiber sensor and detection system thereof

Abstract

The utility model discloses an optical fiber sensor and detection system thereof, relate to optical fiber sensor technical field, and the optical fiber sensor includes: first multimode optical fiber;Second multimode optical fiber;Photonic crystal fiber, and the both ends of photonic crystal fiber are connected with the end of first multimode optical fiber and second multimode optical fiber respectively, and photonic crystal fiber is curved structure, and there is a bending section between both ends;Among them, photonic crystal fiber has polishing surface, and the distance between the core center of photonic crystal fiber and polishing surface is less than the radius of photonic crystal fiber. Thus can prolong the optical path of optical fiber sensor, enhance evanescent wave penetration area, improve light leakage intensity, help to improve the coupling efficiency between the film on the surface of optical fiber sensor and light field, improve the sensitivity of optical fiber sensor. Polishing surface can reduce the wall thickness between the core of photonic crystal fiber and the outer wall of photonic crystal fiber, significantly enhance evanescent wave intensity and shorten the metal-light field interaction distance.

Description

Technical Field

[0001] This application relates to the field of fiber optic sensor technology, and in particular to a fiber optic sensor and its detection system. Background Technology

[0002] Fiber optic SPR (Surface Plasmon Resonance) sensors achieve visualized monitoring of changes in the refractive index of a medium by depositing a metal film on a specific structural region of an optical fiber to induce strong coupling between evanescent waves and plasma. However, fiber optic SPR sensors in related technologies suffer from problems such as short optical field coupling paths, insufficient light leakage intensity, and low sensitivity. Utility Model Content

[0003] This application aims to address at least one of the technical problems existing in the prior art or related technologies.

[0004] In view of the above, according to the first aspect of the technical solution of this application, an optical fiber sensor is proposed, comprising: a first multimode optical fiber; a second multimode optical fiber; and a photonic crystal optical fiber, wherein the two ends of the photonic crystal optical fiber are respectively connected to the ends of the first multimode optical fiber and the second multimode optical fiber, the photonic crystal optical fiber has a bent structure, and there is a bend between the two ends of the photonic crystal optical fiber; wherein the photonic crystal optical fiber has a polished surface, and the distance between the core center of the photonic crystal optical fiber and the polished surface is less than the radius of the photonic crystal optical fiber.

[0005] In some of the technical solutions provided in this application, the polished surface is planar and the cross-sectional shape of the photonic crystal fiber is D-shaped.

[0006] In some of the technical solutions provided in this application, there are multiple air holes between the core of the photonic crystal fiber and the outer wall of the photonic crystal fiber, and there is a gap between the air holes and the polished surface.

[0007] In some of the technical solutions provided in this application, the distance between any point on the outer wall of the core of the photonic crystal fiber and the polished surface is greater than or equal to 5 μm.

[0008] In some of the technical solutions provided in this application, the bending radius of the bending section ranges from 1.3 mm to 1.7 mm.

[0009] In some of the technical solutions provided in this application, the length range of the first multimode fiber and the second multimode fiber is 9.95 mm to 10.05 mm, and the length range of the photonic crystal fiber is 4.95 mm to 5.05 mm.

[0010] In some of the technical solutions provided in this application, the outer surfaces of the first multimode fiber, the second multimode fiber, and the photonic crystal fiber are covered with a gold coating.

[0011] In some of the technical solutions provided in this application, the thickness of the gold coating ranges from 45nm to 55nm.

[0012] In some of the technical solutions provided in this application, the gold coating is further covered with a sensitive film, which includes Sc2O3.

[0013] The second aspect of this application proposes a detection system for an optical fiber sensor, comprising: the optical fiber sensor proposed in the first aspect of this application; a group of test solutions, including multiple test solutions, each having a different refractive index, wherein the multiple test solutions can be dropped onto the photonic crystal fiber of the optical fiber sensor, or at least a portion of the photonic crystal fiber can be immersed in the multiple test solutions; a light source connected to one end of the optical fiber sensor; and a spectrometer, wherein the input end of the spectrometer is connected to the other end of the optical fiber sensor, and the output end of the spectrometer is connected to a remote terminal.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: This application extends the optical path of the fiber optic sensor by configuring it with a multi-segment structure combining multimode fiber and photonic crystal fiber, and by making the photonic crystal fiber a bent structure. This enhances the evanescent wave penetration area, increases light leakage intensity, and improves the coupling efficiency between the coating on the fiber optic sensor surface and the optical field, thereby increasing the sensitivity of the fiber optic sensor. Furthermore, by processing polished surfaces on the photonic crystal fiber, the wall thickness between the fiber core and the outer wall of the photonic crystal fiber can be reduced, significantly enhancing the evanescent wave intensity and shortening the metal-optical field interaction distance. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic diagram of the structure of an optical fiber sensor according to an embodiment of this application; Figure 2 for Figure 1 Sectional view of section AA; Figure 3 for Figure 1 Sectional view of section BB; Figure 4 A schematic diagram of the structure of a detection system for an optical fiber sensor according to an embodiment of this application; Figure 5 Transmittance versus wavelength curves obtained through test solutions of different refractive indices, according to one embodiment of this application; Figure 6 This application provides an embodiment of linear fitting of multiple sets of refractive index and wavelength values ​​obtained through test solutions with different refractive indices.

[0016] in, Figures 1 to 6 The correspondence between the reference numerals and component names in the attached drawings is as follows: 100. Fiber optic sensor; 110. First multimode fiber; 120. Photonic crystal fiber; 121. Bending section; 122. Core of photonic crystal fiber; 123. Polished surface; 124. Pore; 130. Second multimode fiber; 140. Gold coating; 150. Sensitive membrane; 200. Detection system of fiber optic sensor; 210. Solution to be tested; 220. Light source; 230. Spectrometer; 240. Remote terminal. Detailed Implementation

[0017] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0018] The following reference Figures 1 to 6 This invention describes an optical fiber sensor 100 and an optical fiber sensor detection system 200 provided according to some embodiments of the present invention.

[0019] In one embodiment according to this application, such as Figure 1 , Figure 2 and Figure 3 As shown, this application proposes an optical fiber sensor 100, including: a first multimode optical fiber 110; a second multimode optical fiber 130; and a photonic crystal optical fiber 120. The two ends of the photonic crystal optical fiber 120 are respectively connected to the ends of the first multimode optical fiber 110 and the second multimode optical fiber 130. The photonic crystal optical fiber 120 has a bent structure, and there is a bend 121 between the two ends of the photonic crystal optical fiber 120. The photonic crystal optical fiber 120 has a polished surface 123, and the distance between the center of the core 122 of the photonic crystal optical fiber and the polished surface 123 is smaller than the radius of the photonic crystal optical fiber 120.

[0020] The fiber optic sensor 100 proposed in this application is a fiber optic SPR sensor, which has a multi-segment structure. Specifically, the fiber optic sensor 100 includes a first multimode fiber 110, a second multimode fiber 130, and a photonic crystal fiber 120. The first multimode fiber 110 and the second multimode fiber 130 have straight structures, while the photonic crystal fiber 120 has a bent structure. Both ends of the photonic crystal fiber 120 are connected to the first multimode fiber 110 and the second multimode fiber 130, respectively. Because the fiber optic sensor 100 has a multimode fiber-photonic crystal fiber-multimode fiber structure, the change in fiber type during light propagation within the sensor leads to a change in the SPR incident angle at the sensing interface, thereby improving the sensitivity of the fiber optic sensor 100. The photonic crystal fiber 120 has a bend 121 between its two ends, giving the fiber optic sensor 100 an overall U-shaped structure, further enhancing its sensitivity.

[0021] In one possible embodiment, a multimode fiber with a core diameter of 62.5 μm and a cladding diameter of 125 μm is selected. First, the coating at one end is stripped using fiber strippers. Then, any remaining coating is wiped clean with lint-free paper dampened with anhydrous ethanol, exposing the cladding. A 10 mm long exposed cladding section is then cut using a fiber cleaver, with an error controlled within ±0.5 mm. This process is repeated once to obtain two multimode fibers with 10 mm of coating exposed at the same end, designated as the first multimode fiber 110 and the second multimode fiber 130, respectively. Another photonic crystal fiber 120 with a core diameter of 9 μm and a cladding diameter of 125 μm is taken. The coating at one end is stripped and cleaned using the same steps, and then a 5 mm uncoated exposed section is cut. Using a fiber fusion splicer, the three stripped fiber sections are sequentially fused together to form a fiber substrate consisting of a 10 mm multimode fiber, a 5 mm photonic crystal fiber, and a 10 mm multimode fiber, with a total length of 25 mm.

[0022] Furthermore, such as Figure 2 As shown, the photonic crystal fiber 120 has a polished surface 123, and the distance between the center of the fiber core 122 and the polished surface 123 is smaller than the radius of the photonic crystal fiber 120. By processing the polished surface 123 on the photonic crystal fiber 120, the wall thickness between the fiber core 122 and the outer wall of the photonic crystal fiber 120 can be reduced, significantly enhancing the evanescent wave intensity and shortening the metal-optical field interaction distance.

[0023] This application extends the optical path of the fiber optic sensor 100 by configuring it into a multi-segment structure using a combination of multimode fiber and photonic crystal fiber 120, and by configuring the photonic crystal fiber 120 into a bent structure. This enhances the evanescent wave penetration area, increases the light leakage intensity, and helps improve the coupling efficiency between the coating on the surface of the fiber optic sensor 100 and the optical field, thereby improving the sensitivity of the fiber optic sensor 100. Furthermore, by processing a polished surface 123 on the photonic crystal fiber 120, the wall thickness between the core 122 and the outer wall of the photonic crystal fiber 120 can be reduced, significantly enhancing the evanescent wave intensity and shortening the metal-optical field interaction distance.

[0024] In some embodiments, optionally, such as Figure 2 As shown, the polished surface 123 is a plane, and the cross-sectional shape of the photonic crystal fiber 120 is D-shaped.

[0025] In this embodiment, the polished surface 123 is defined. The polished surface 123 is planar, and the cross-sectional shape of the photonic crystal fiber 120 is D-shaped. Specifically, after the multimode fiber and the photonic crystal fiber 120 are fused together, the polished surface 123 of the photonic crystal fiber 120 is processed using a wheel-type side polishing machine. The two ends of the newly fabricated fiber substrate are straightened with 10g weights and attached to a ceramic V-shaped fixture. The fixture is then inserted into the wheel-type polishing machine, and an 800-grit diamond wheel is used to polish the photonic crystal fiber 120 at a speed of 100 rpm, with a feed rate of 5μm per step. The transmission loss at 1550nm is monitored in real time, and the process stops when the loss reaches 1.5dB. The polishing is then repeated with 5μm, 2μm, and 1μm sandpaper, with the speed reduced to 50 rpm and the feed rate reduced to 1μm per step, forming the polished surface 123. The minimum distance between the polished surface 123 and the outer wall of the photonic crystal fiber 120 ranges from 5μm to 10μm.

[0026] The planar polished surface 123 is easier to process, its processing parameters are controllable, it is easy to mass-produce, and it has practical application value.

[0027] In some embodiments, optionally, such as Figure 2 As shown, there are multiple air holes 124 between the core 122 of the photonic crystal fiber and the outer wall of the photonic crystal fiber 120, and there is a gap between the air holes 124 and the polished surface 123.

[0028] In this embodiment, the structure of the photonic crystal fiber 120 is further defined. Multiple air holes 124 are provided between the fiber core 122 and the outer wall of the photonic crystal fiber 120, and there is a spacing between the air holes 124 and the polished surface 123. This ensures that the overall mechanical strength of the photonic crystal fiber 120 meets the usage requirements and prevents cracking. Specifically, the minimum spacing between the air holes 124 and the polished surface 123 is greater than or equal to 1 μm.

[0029] In some embodiments, optionally, the distance between any point on the outer wall of the core 122 of the photonic crystal fiber and the polished surface 123 is greater than or equal to 5 μm.

[0030] In this embodiment, the photonic crystal fiber 120 is further defined. The distance between any point on the outer wall of the core 122 of the photonic crystal fiber and the polished surface 123 is greater than or equal to 5 μm, that is, the minimum distance between the outer wall of the core 122 and the polished surface 123 is greater than or equal to 5 μm. A quartz layer exists between the core 122 and the outer wall of the photonic crystal fiber. If the quartz layer is too thin, the mechanical strength of the photonic crystal fiber 120 will be poor, making it prone to cracking and fiber breakage. Furthermore, if the distance between the core and the polished surface 123 is too small, excessive light field leakage will easily occur, leading to increased transmission loss. By limiting the minimum distance between the outer wall of the core 122 and the polished surface 123 to greater than or equal to 5 μm, it is possible to ensure that the mechanical strength of the photonic crystal fiber 120 meets the usage requirements, and also to avoid excessive light field leakage, thereby improving the performance of the fiber optic sensor 100.

[0031] In some embodiments, the bending radius of the bending segment 121 may optionally range from 1.3 mm to 1.7 mm.

[0032] In this embodiment, the structure of the photonic crystal fiber 120 is further defined. The photonic crystal fiber 120 has a U-shaped structure, meaning that the two sides of the bent section 121 of the photonic crystal fiber 120 are nearly symmetrical. Specifically, the bending radius of the bent section 121 ranges from 1.3 mm to 1.7 mm. Understandably, if the bending radius of the bent section 121 is too large, the optical path length of the fiber optic sensor 100 will be insufficient; if the bending radius of the bent section 121 is too small, the photonic crystal fiber 120 is easily damaged. Therefore, this application limits the bending radius of the bent section 121 to the range of 1.3 mm to 1.7 mm, thereby both extending the optical path of the fiber optic sensor 100 and avoiding damage to the photonic crystal fiber 120. In one possible embodiment, the bending radius of the bent section 121 is 1.5 mm.

[0033] In some embodiments, the lengths of the first multimode fiber 110 and the second multimode fiber 130 may range from 9.95 mm to 10.05 mm, and the length of the photonic crystal fiber 120 may range from 4.95 mm to 5.05 mm.

[0034] In this embodiment, the dimensions of the first multimode fiber 110, the second multimode fiber 130, and the photonic crystal fiber 120 are defined. Specifically, the lengths of the first multimode fiber 110 and the second multimode fiber 130 range from 9.95 mm to 10.05 mm, and the length of the photonic crystal fiber 120 ranges from 4.95 mm to 5.05 mm. In one possible embodiment, the lengths of both the first multimode fiber 110 and the second multimode fiber 130 are 10 mm, and the length of the photonic crystal fiber 120 is 5 mm.

[0035] In some embodiments, optionally, such as Figure 1 , Figure 2 and Figure 3 As shown, the outer surfaces of the first multimode fiber 110, the second multimode fiber 130, and the photonic crystal fiber 120 are covered with a gold coating 140.

[0036] In this embodiment, the structure of the fiber optic sensor 100 is further defined. The surfaces of the first multimode fiber 110, the second multimode fiber 130, and the photonic crystal fiber 120 are all covered with a gold coating 140. Specifically, the gold coating 140 is prepared on the surface of the fiber substrate using an ion sputtering apparatus. The vacuum chamber maintains a high vacuum condition throughout the coating process, and the end of the fiber substrate is fixed on a glass slide, positioned directly below the gold target. Two sputtering cycles are performed at a set current of 8 mA, with each cycle lasting 90 seconds. After the first sputtering cycle, the fiber substrate is rotated 180° and placed back into the glass cover of the magnetron sputtering apparatus for a second sputtering cycle to ensure uniform deposition of the gold coating 140 on the bent section 121 of the photonic crystal fiber 120. This gold coating 140 exhibits good density and adhesion, providing a stable underlying support for subsequent coatings.

[0037] In some embodiments, the thickness of the gold coating 140 may optionally range from 45 nm to 55 nm.

[0038] In this embodiment, the thickness range of the gold coating 140 is defined. Specifically, the thickness range of the gold coating 140 is 45 nm to 55 nm. Within this thickness range, the gold coating 140 can form efficient coupling with the surface plasmon waves excited by the incident light, producing significant resonant absorption or reflection peak shift, ensuring sensing sensitivity. In one possible embodiment, the thickness of the gold coating 140 is 50 nm.

[0039] In some embodiments, optionally, such as Figure 1 , Figure 2 and Figure 3 As shown, the gold coating 140 is further covered with a sensitive film 150, which includes Sc2O3.

[0040] In this embodiment, the structure of the fiber optic sensor 100 is further defined. The gold coating 140 of the fiber optic sensor 100 is further covered with a sensitive film 150, which comprises Sc2O3. Specifically, Sc2O3 is coated as the sensitive film 150 material using an electrostatic self-assembly method. First, 500 mg of CS (Chitosan) powder is dissolved in 50 ml of a 4% glacial acetic acid aqueous solution. Then, 10 ml of the prepared CS solution is measured, and the Sc2O3 powder is added to the CS solution. The solution is then sonicated for 15 min to form a stable milky white suspension. Next, a 5 mg / ml PSS (Poly(sodium 4-styrenesulfonate)) solution is prepared. The prepared fiber optic sensor 100 is immersed in the PSS solution for 2 min and then allowed to stand at room temperature for 10 min. The fiber optic sensor 100 was then immersed in a chitosan solution containing Sc2O3 for 30 minutes to ensure uniform adsorption of the film layer on the surface of the gold coating 140. It was then removed and placed in a light-protected, dry environment to air dry for 24 hours, forming a complete and uniform sensitive film 150.

[0041] By utilizing a highly dense gold coating 140 and a sensitive film 150 to form a composite film layer on the outside of the first multimode fiber 110, the photonic crystal fiber 120, and the second multimode fiber 130, a highly sensitive response to minute changes in refractive index is achieved.

[0042] The second aspect of this application proposes a detection system 200 for an optical fiber sensor, comprising: the optical fiber sensor 100 proposed in the first aspect of this application; a group of test solutions 210, including multiple test solutions 210, each having a different refractive index, wherein the multiple test solutions 210 can be dropped onto the photonic crystal fiber 120 of the optical fiber sensor 100, or at least a portion of the photonic crystal fiber 120 can be immersed in the multiple test solutions 210; a light source 220 connected to one end of the optical fiber sensor 100; and a spectrometer 230, the input end of which is connected to the other end of the optical fiber sensor 100, and the output end of which is connected to a remote terminal 240.

[0043] like Figure 4As shown, this application proposes a detection system 200 for detecting an optical fiber sensor 100. The detection system includes an optical fiber sensor 100, a set of test solutions 210, a light source 220, and a spectrometer 230. When detecting the optical fiber sensor 100, one end of the optical fiber sensor 100 is connected to the light source 220, and the other end is connected to the input of the spectrometer 230. Simultaneously, the output of the spectrometer 230 is connected to a remote terminal 240 to transmit the detection results. The set of test solutions 210 includes multiple test solutions 210, each with a different refractive index. When detecting the optical fiber sensor 100, the multiple test solutions 210 can be dropped onto the curved capillary optical fiber of the optical fiber sensor 100, or the curved capillary optical fiber of the optical fiber sensor 100 can be immersed in the multiple test solutions 210.

[0044] In one possible embodiment, a set of sodium chloride standard solutions (i.e., test solutions 210) is prepared to test the refractive index response of the fiber optic sensor 100. This set of sodium chloride standard solutions includes multiple solutions with different refractive indices (i.e., test solutions 210), with refractive index values ​​of 1.33189, 1.34675, 1.35765, 1.36698, and 1.37322, respectively. During testing, solutions with different refractive indices are added dropwise to the U-shaped sensing region (i.e., the bent section 121 of the photonic crystal fiber 120) using a dropper. Transmission spectra are acquired using software, and the degree of redshift at the resonance trough is observed. To ensure complete wavelength response and high-sensitivity detection, a spectrometer 230 is used to construct the detection system. The spectrometer 230 covers a wavelength range of 1000 nm to 1600 nm and possesses good light intensity stability.

[0045] Figure 5 The figure shows the wavelength versus transmittance curves obtained using solutions with five different refractive indices. Figure 6 The blue line represents the linear regression line formed by linearly fitting the detection results obtained from solutions with five different refractive indices. The formula is y = 7410x - 8744.9, and the coefficient of determination is R0. 2 It is 0.9653. Figure 6 The green line represents the linear line formed by linearly fitting the detection results obtained from solutions with refractive indices between 1.33 and 1.35, with the formula y = 5550x - 6255 and a coefficient of determination R0. 2 It is 0.9879. Figure 6 The red line represents the linear line formed by linearly fitting the detection results obtained from solutions with refractive indices between 1.35 and 1.37, with the formula y = 9450x - 11523 and the coefficient of determination R0. 2 It is 0.9799.

[0046] The detection system 200 of the fiber optic sensor proposed in the second aspect of this application has all the beneficial effects of the fiber optic sensor 100 proposed in the first aspect of this application because it includes the fiber optic sensor 100 proposed in the first aspect of this application.

[0047] In this utility model, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "join," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "join" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0048] In the description of this utility model, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0049] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An optical fiber sensor, characterized in that, include: First multimode fiber; Second multimode fiber; A photonic crystal fiber, wherein the two ends of the photonic crystal fiber are respectively connected to the ends of a first multimode fiber and a second multimode fiber, the photonic crystal fiber has a bent structure, and there is a bend between the two ends of the photonic crystal fiber; The photonic crystal fiber has a polished surface, and the distance between the core center of the photonic crystal fiber and the polished surface is less than the radius of the photonic crystal fiber.

2. The fiber optic sensor according to claim 1, characterized in that, The polished surface is planar, and the cross-sectional shape of the photonic crystal fiber is D-shaped.

3. The fiber optic sensor according to claim 1, characterized in that, The photonic crystal fiber has multiple air holes between its core and its outer wall, and there is a gap between the air holes and the polished surface.

4. The fiber optic sensor according to claim 1, characterized in that, The distance between any point on the outer wall of the core of the photonic crystal fiber and the polished surface is greater than or equal to 5 μm.

5. The fiber optic sensor according to claim 1, characterized in that, The bending radius of the bending section ranges from 1.3 mm to 1.7 mm.

6. The fiber optic sensor according to claim 1, characterized in that, The lengths of the first multimode fiber and the second multimode fiber range from 9.95 mm to 10.05 mm, and the length of the photonic crystal fiber ranges from 4.95 mm to 5.05 mm.

7. The fiber optic sensor according to any one of claims 1 to 6, characterized in that, The outer surfaces of the first multimode fiber, the second multimode fiber, and the photonic crystal fiber are covered with a gold coating.

8. The fiber optic sensor according to claim 7, characterized in that, The thickness of the gold coating ranges from 45 nm to 55 nm.

9. The fiber optic sensor according to claim 7, characterized in that, The gold coating is further covered with a sensitive membrane, which includes Sc2O3.

10. A detection system for an optical fiber sensor, characterized in that, include: The fiber optic sensor as described in any one of claims 1 to 9; The test solution group includes multiple test solutions, each of which has a different refractive index. The multiple test solutions can be dropped onto the photonic crystal fiber of the optical fiber sensor, or at least a portion of the photonic crystal fiber can be immersed in the multiple test solutions. A light source is connected to one end of the fiber optic sensor; A spectrometer, the input end of which is connected to the other end of the fiber optic sensor, and the output end of which is connected to a remote terminal.

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