Optical fiber dislocation type refractive index sensor based on MXene spraying transfer

Abstract

The invention belongs to the technical field of optical fiber sensor preparation, and relates to an optical fiber dislocation type refractive index sensor based on MXene spraying transfer. According to the sensor, a single-mode optical fiber, a coreless optical fiber, a multimode optical fiber, a leading-out coreless optical fiber, a leading-out single-mode optical fiber and an MXene material are distributed according to the propagation direction of light; a multimode optical fiber is connected between the lead-in coreless optical fiber and the lead-out coreless optical fiber through dislocation welding; the multi-mode optical fiber comprises a staggered multi-mode optical fiber cladding and a staggered multi-mode optical fiber core; the MXene material is coated on the surfaces of the leading-in coreless optical fiber, the staggered multimode optical fiber cladding and the leading-out coreless optical fiber; introducing a single-mode optical fiber and introducing a coreless optical fiber; and the leading-out coreless optical fiber and the leading-out single-mode optical fiber are aligned and welded. The introduction single-mode fiber is used for introducing a light source; a coreless optical fiber is introduced as a light beam expander, and a cladding mode is excited to be output to a multimode optical fiber; and the staggered multimode fiber cladding and the staggered multimode fiber core excite the multimode interference effect of the multimode fiber through a staggered structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber sensing and sensor preparation, and in particular relates to an optical fiber dislocation type refractive index sensor based on MXene spray transfer. Background Art

[0002] Fiber optic sensors have been widely used in physics, chemistry, and biological measurement due to their high sensitivity, compact structure, fast response speed, anti-electromagnetic interference, and long-distance real-time detection. Traditional fiber optic refractive index sensors mostly use a tapered fiber structure. Although this structure can provide higher sensitivity, it is not easy to operate and use due to its low mechanical strength and complex manufacturing.

[0003] In order to improve the sensitivity and stability of sensors, researchers have proposed a variety of new fiber optic sensor structures in recent years. For example, the fiber optic sensor based on the open-cavity Mach-Zehnder interferometer is prepared by large-dislocation fusion technology, and by monitoring the wavelength drift of the interference fringes, it achieves high-sensitivity solution concentration detection; and the sensor of this structure is not only small, highly repeatable, but also relatively simple to manufacture. Another small-dislocation fiber optic sensor based on a semi-open cavity structure can simultaneously measure underwater temperature and salinity. By adjusting the design parameters of the sensor, its sensitivity and stability are improved.

[0004] Current misaligned splicing fiber optic sensors, such as those based on open-cavity Mach-Zehnder (MZ) interferometers, use large misalignment fusion technology to achieve high-sensitivity solution concentration detection. However, such sensors are easily affected by temperature changes in complex environments in practical applications, resulting in reduced measurement accuracy. However, these sensors still face some technical challenges when facing complex environments and extreme conditions. First, fiber optic sensors are easily damaged in corrosive environments and require special materials for protection. Second, existing sensors still have room for improvement in sensitivity and stability. For example, although sensors based on open-cavity structures have high sensitivity, they are easily affected by changes in ambient temperature in practical applications, resulting in reduced measurement accuracy. Although sensors based on semi-open cavity structures perform well in terms of sensitivity, their complex structure and high production cost limit the possibility of large-scale application.

[0005] The above two existing sensors are in urgent need of performance improvement for complex environments and extreme conditions, where higher sensitivity and stability are required. In addition to structural improvements, existing methods for improving sensitivity and stability also include methods of coating sensitive materials. MXene is a two-dimensional material with excellent conductivity, mechanical flexibility and chemical stability, and is an ideal refractive index sensitive material. By evenly spraying MXene material on the surface of the optical fiber, the refractive index detection accuracy and stability of the sensor can be significantly improved. Compared with traditional coating methods, MXene coating not only provides higher sensitivity, but also makes the spraying process simpler and more controllable, with better coating uniformity, and can effectively avoid measurement errors caused by uneven coating. MXene coating not only provides high sensitivity, but also effectively avoids measurement errors caused by uneven coating. At the same time, it has excellent corrosion resistance and is suitable for various complex detection environments. The optical fiber dislocation refractive index sensor based on MXene spray transfer, combined with the advantages of high sensitivity and high mechanical strength, overcomes the shortcomings of traditional sensors and has broad application prospects. Summary of the invention

[0006] The purpose of the present invention is to address the technical defects of existing refractive index sensors, that is, the detection sensitivity and stability need to be further improved, and propose an optical fiber dislocation refractive index sensor based on MXene spray transfer.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme.

[0008] As a first aspect of the present invention, a fiber dislocation type refractive index sensor based on MXene spray transfer is proposed, wherein an introduction single-mode fiber, an introduction coreless fiber, a multimode fiber, an extraction coreless fiber, an extraction single-mode fiber and a MXene material layer are distributed in the propagation direction of light; the introduction coreless fiber and the extraction coreless fiber are connected to the multimode fiber by dislocation fusion splicing;

[0009] The introduced single-mode optical fiber, multi-mode optical fiber and the led-out single-mode optical fiber are all in transmission fundamental mode; and the multi-mode optical fiber transmits fundamental mode and high-order mode; the introduced coreless optical fiber and the led-out coreless optical fiber are all in cladding mode;

[0010] The multimode optical fiber comprises a staggered multimode optical fiber cladding and a staggered multimode optical fiber core;

[0011] The introduced coreless optical fiber is a beam expander; the led-out coreless optical fiber is a mode mixer, which improves the sensitivity of the sensor;

[0012] The multimode optical fiber includes a staggered multimode optical fiber cladding and a staggered multimode optical fiber core, has a larger core diameter and mode propagation capability, and can effectively excite the cladding mode of the multimode optical fiber through a staggered splicing structure, thereby generating a significant multimode interference effect, thereby improving the sensitivity of the sensor.

[0013] The MXene material layer is spray-coated on the surface of the sensing area;

[0014] The sensing area surface includes the introduction of the coreless optical fiber, the dislocation multimode optical fiber cladding and the lead-out coreless optical fiber surface;

[0015] The MXene material has a unique layered structure, abundant surface functional groups, high conductivity, high specific surface area, and excellent mechanical structure and stability;

[0016] The spray coating has the advantages of efficient production, uniform coating, simple operation, and easy and flexible adaptation and control of coating thickness.

[0017] The introduced single-mode optical fiber is connected to the introduced coreless optical fiber; the introduced coreless optical fiber is connected to the offset multimode optical fiber cladding; the offset multimode optical fiber cladding is connected to the lead-out coreless optical fiber, and the lead-out coreless optical fiber is connected to the lead-out single-mode optical fiber; the introduced coreless optical fiber, multimode optical fiber, and lead-out coreless optical fiber are connected to the lead-out single-mode optical fiber; the offset multimode optical fiber cladding is connected to the offset multimode optical fiber core; the multimode optical fiber is connected to the MXene material layer.

[0018] The fusion splicing method between the introduced single-mode optical fiber and the introduced coreless optical fiber is alignment fusion splicing.

[0019] The fusion splicing method between the lead-out coreless optical fiber and the lead-out single-mode optical fiber is alignment fusion splicing.

[0020] The introduced single-mode optical fiber is used to introduce a light source; the introduced coreless optical fiber is used as a light beam expander to excite the cladding mode and output it to the multi-mode optical fiber.

[0021] The dislocated multimode optical fiber cladding and the dislocated multimode optical fiber core excite the multimode interference effect of the multimode optical fiber through the dislocated structure.

[0022] The lead-out coreless optical fiber plays a role in mode mixing and uniform distribution, thereby improving the coupling efficiency of the interference mode. The lead-out single-mode optical fiber 6 outputs an optical signal for subsequent reception. The refractive index range of the MXene material layer is between 1.68 and 2.5.

[0023] As another aspect of the present invention, a method for preparing an optical fiber dislocation refractive index sensor based on MXene spray transfer is proposed, comprising the following steps:

[0024] S1: Making a multimode optical fiber staggered structure, specifically including the following steps:

[0025] S11: stripping the coating of the introduced single-mode optical fiber and the introduced coreless optical fiber, and then fixing the introduced single-mode optical fiber and the introduced coreless optical fiber;

[0026] S12: cutting the introduced single-mode optical fiber and the introduced coreless optical fiber to obtain a flat end face;

[0027] S13: performing aligned discharge welding on the introduced single-mode optical fiber and the introduced coreless optical fiber;

[0028] S14: performing staggered fusion splicing on one side of the multimode optical fiber and the lead-in coreless optical fiber, and performing staggered fusion splicing on the other side of the multimode optical fiber and the lead-out coreless optical fiber in the opposite direction;

[0029] S15: Use a fiber fusion splicer to align and discharge-fusion-splice the lead-out coreless optical fiber and the lead-out single-mode optical fiber;

[0030] So far, from S11 to S15, a multimode optical fiber dislocation structure is prepared;

[0031] S2: Preparation of Ti3C2Tx MXene dispersion;

[0032] S3: Spraying process to transfer MXene dispersion;

[0033] S31: fixing the multimode optical fiber dislocation structure on a glass slide and then placing the glass slide on a hot stage and heating it;

[0034] S32: spraying the MXene dispersion onto the multimode optical fiber dislocation structure at a uniform speed;

[0035] S33: Observe whether there is a MXene film in a specific area of ​​the surface and measure the thickness of the MXene film;

[0036] The uniform speed spraying in S32 and the measurement of the thickness of the MXene film in S33 specifically control the spraying time according to the rate, maintain the same rate, and the initial spraying time is 5 to 10 minutes; after multiple spraying, measure the actual film thickness, and adjust the subsequent spraying time to achieve the required thickness; during the spraying process, in order to obtain the best spraying effect, ensure that the distance between the spray gun and the optical fiber sensing structure is maintained between 10 and 15 cm.

[0037] S11 The coating of the introduced single-mode optical fiber and the introduced coreless optical fiber is stripped by using optical fiber pliers; the fixed introduction of the single-mode optical fiber and the introduced coreless optical fiber is fixed by using optical fiber clamps;

[0038] The cutting of the introduced single-mode optical fiber and the introduced coreless optical fiber in S12 is performed by using an electric optical fiber cutting knife;

[0039] S13 is implemented by aligning and discharging the introduced single-mode optical fiber and the introduced coreless optical fiber using an optical fiber fusion splicer;

[0040] S14: performing staggered fusion splicing of the multimode optical fiber and the lead-in coreless optical fiber or the lead-out coreless optical fiber respectively, and using an optical fiber fusion splicer to achieve fusion splicing;

[0041] When S15 is implemented, the discharge intensity of the aligning discharge welding is set to 20 bits;

[0042] The length of the single-mode optical fiber, coreless optical fiber, and multi-mode optical fiber described in S11, S12, S13, S14, and S15 is 0.8 to 1.2 cm.

[0043] S14: The discharge mode used in the offset welding is a multimode optical fiber fusion splicing mode and the displacement ratio of the offset welding is 30% to 80% of the multimode optical fiber diameter.

[0044] S15: the discharge time of the discharge welding is set to 1000-1200ms;

[0045] S21: adding 0.7-0.9 g of LiF to 9-11 mL of 8-10 mol / L hydrochloric acid, stirring for 4-6 min to allow LiF to fully react with the hydrochloric acid, as an etching agent for the reaction system;

[0046] S22: slowly adding 1-1.2 g of Ti3AlC2 MAX powder to the etchant and reacting at 35-45° C. for 40-50 hours to obtain a reaction mixture;

[0047] The time for adding 1-1.2 g of Ti3AlC2 MAX powder exceeds 10 minutes;

[0048] S23: washing the reaction mixture by centrifugation with deionized water for 3 to 5 times at a centrifugal speed of 3000 to 3500 rpm until the pH value of the supernatant is greater than 6 to obtain a product;

[0049] S24: vacuum filtering the product on a porous polytetrafluoroethylene membrane to obtain a layered cake-like slurry and then separating it;

[0050] The separation obtains a slurry and a solid;

[0051] The slurry is Ti3C2Tx, and the solid is Ti3AlC2 that is not completely etched;

[0052] S25: 0.1-0.12 g of the slurry is added to 90-110 mL of deionized water or ethanol, and ultrasonicated in an ice water bath for 45 minutes to 1 hour to obtain a dispersion;

[0053] S26: centrifuging the dispersion at 3500-4000 rpm for 25-35 min to remove multilayer MXene aggregates to obtain a MXene dispersion and storing it for later use;

[0054] The heating temperature range of S31 is 90-110° C. to accelerate the evaporation of the spraying liquid and prevent the solution from gathering into water droplets; the heating time is about 5-8 minutes;

[0055] S32 The uniform speed spraying is performed by pouring the MXene dispersion into a spray gun and spraying it at a small flow rate at a uniform speed, so that the MXene dispersion drips on the multimode optical fiber dislocation structure in a mist form and evaporates quickly without converging water droplets;

[0056] The specific surface area in S33 is the surface where the coreless optical fiber is introduced, the cladding of the offset multimode optical fiber, and the coreless optical fiber is led out; the thickness of the MXene film is measured by a step meter; and the observation of whether there is a MXene film in the specific surface area is achieved by a metallographic microscope.

[0057] Beneficial Effects

[0058] The optical fiber dislocation refractive index sensor based on MXene spray transfer proposed in the present invention has the following beneficial effects compared with the prior art:

[0059] 1. The proposed refractive index sensor uses the introduction of coreless fiber as a beam expander and the extraction of coreless fiber as a mode mixer, which improves the sensitivity of the sensor;

[0060] 2. The proposed refractive index sensor has a section of multimode optical fiber displaced. The multimode optical fiber includes a displaced multimode optical fiber cladding and a displaced multimode optical fiber core, and has a larger core diameter and mode propagation capability. The displaced splicing structure can effectively excite the cladding mode of the multimode optical fiber, thereby generating a significant multimode interference effect, thereby improving the sensitivity of the sensor;

[0061] 3. The proposed refractive index sensor is sprayed with a new material called MXene on the surface of the sensing area. MXene has the advantages of a unique layered structure, rich surface functional groups, high conductivity, high specific surface area, excellent mechanical structure and stability. With the combined effect of these characteristics, the refractive index sensitivity and stability of the sensor can be significantly improved, making it suitable for high-precision detection in complex environments.

[0062] 4. For the proposed MXene-coated refractive index sensor, the MXene material is transferred using a spray coating process, which has significant advantages in terms of efficient production, uniform coating, simple operation, flexible adaptability, and control of coating thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 Schematic diagram of the structure of the optical fiber dislocation refractive index sensor based on MXene spray transfer;

[0064] Figure 2 Schematic diagram of the cross-section of the offset weld structure.

[0065] Illustration Description:

[0066] 1-introducing single-mode optical fiber, 2-introducing coreless optical fiber, 3-misaligned multimode optical fiber cladding, 4-misaligned multimode optical fiber core, 5-leading out coreless optical fiber, 6-leading out single-mode optical fiber, 7-MXene material coating area. DETAILED DESCRIPTION

[0067] The following is a description of the preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text. In the drawings, components with the same structure are represented by the same numerical labels, and components with similar structures or functions are represented by similar numerical labels. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0068] Example 1

[0069] This embodiment provides a fiber optic dislocation refractive index sensor based on MXene spray transfer, such as Figure 1 As shown, according to the propagation direction of light, there are an introduction single-mode optical fiber 1, an introduction coreless optical fiber 2, a multimode optical fiber, an extraction coreless optical fiber 5, an extraction single-mode optical fiber 6, and a MXene material coating area 7; the introduction coreless optical fiber 2 and the extraction coreless optical fiber 5 are connected to the multimode optical fiber by offset fusion splicing;

[0070] The multimode optical fiber comprises a staggered multimode optical fiber cladding 3 and a staggered multimode optical fiber core 4;

[0071] The MXene material is coated on the surface of the introduced coreless optical fiber 2, the dislocated multimode optical fiber cladding 3 and the lead-out coreless optical fiber 5;

[0072] The introduced single-mode optical fiber 1 is connected to the introduced coreless optical fiber 2; the introduced coreless optical fiber 2 is connected to the offset multimode optical fiber cladding 3; the offset multimode optical fiber cladding 3 is connected to the lead-out coreless optical fiber 5, and the lead-out coreless optical fiber 5 is connected to the lead-out single-mode optical fiber 6; the introduced coreless optical fiber 2, the multimode optical fiber, and the lead-out coreless optical fiber 5 are connected to the lead-out single-mode optical fiber 6; the offset multimode optical fiber cladding 3 is connected to the offset multimode optical fiber core 4; the multimode optical fiber is connected to the MXene material layer.

[0073] The fusion splicing method between the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 is alignment fusion splicing.

[0074] The fusion splicing method between the lead-out coreless optical fiber 5 and the lead-out single-mode optical fiber 6 is alignment fusion splicing.

[0075] The introduction single-mode optical fiber 1 is used to introduce a light source.

[0076] The coreless optical fiber 2 is introduced as a light beam expander to excite the cladding mode.

[0077] The dislocated multimode optical fiber cladding 3 and the dislocated multimode optical fiber core 4 excite the multimode interference effect of the multimode optical fiber through the dislocated structure.

[0078] The lead-out coreless optical fiber 5 is a mode mixer, which plays the role of mode mixing and uniform distribution, thereby improving the coupling efficiency of the interference mode.

[0079] The lead-out single-mode optical fiber 6 is the output of light for subsequent receiving of optical signals.

[0080] The MXene material is a high refractive index sensitive material, which increases the refractive index detection sensitivity of the sensor and enhances the stability of the dislocation sensing structure.

[0081] An optical fiber dislocation refractive index sensor based on MXene spray transfer and a manufacturing method thereof, comprising the following steps:

[0082] S1: Make as Figure 1 The multimode optical fiber misalignment structure shown;

[0083] The specific production of the dislocation structure includes the following steps:

[0084] S11: using a fiber pliers to partially strip the coating of the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2, and then fixing the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 with a fiber clamp;

[0085] S12: using an electric fiber cleaver to cut the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 to obtain a flat end face;

[0086] S13: using an optical fiber fusion splicer to align and discharge-fusion-splice the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2;

[0087] S14: Using an optical fiber fusion splicer to perform staggered fusion splicing of the multimode optical fiber and the introduced coreless optical fiber 1;

[0088] At the same time, the other side of the multimode optical fiber also carries out the displacement welding of the coreless optical fiber 5 in the opposite direction, such as Figure 2 shown.

[0089] S15: Finally, use a fiber fusion splicer to align and discharge-fusion-splice the lead-out coreless optical fiber 5 and the lead-out single-mode optical fiber 6;

[0090] In one embodiment of the present invention, the length of the coreless optical fiber and the multimode optical fiber is 0.8-1.2 cm.

[0091] In one embodiment of the present invention, the offset welding displacement in step S14 is 62.5 μm, the discharge mode adopted is the multimode fiber fusion mode, the discharge intensity is set to 20 bits, and the discharge time is set to 1000 ms.

[0092] S2: Preparation of Ti3C2Tx MXene dispersion;

[0093] S21: 0.7 g of LiF was added to 9 mL of 8 mol / L hydrochloric acid and stirred for 4 min to allow the LiF and hydrochloric acid to react fully as an etchant in the reaction system;

[0094] S22: Slowly add 1 g of Ti3AlC2 MAX powder to the etchant (addition time exceeds 10 min). The system reacts at 35°C for 40 h to obtain a reaction mixture;

[0095] S23: washing the reaction mixture by centrifugation with deionized water three times at a centrifugal speed of 3000 rpm until the pH value of the supernatant is greater than 6;

[0096] S24: vacuum filtering the product on a porous polytetrafluoroethylene membrane to obtain a two-layer cake-like slurry and separating the slurry (Ti3C2Tx) from the solid (Ti3AlC2 that is not completely etched);

[0097] S25: 0.1 g Ti3C2Tx slurry was added to 90 mL deionized water or ethanol and ultrasonicated in an ice water bath for 45 min;

[0098] S26: The dispersion is then centrifuged at 3500 rpm for 25 min to remove multi-layer MXene aggregates, thereby obtaining a MXene dispersion, which is stored in a reagent bottle for later use;

[0099] Step 3: Spraying process to transfer MXene;

[0100] S31: Fix the optical fiber sensing structure on a glass slide, place it on a hot plate, and set the temperature to 90° C. Heating is performed to accelerate the evaporation of the spray liquid and prevent the solution from gathering into water droplets;

[0101] S32: Pour the prepared MXene dispersion into the spray gun and spray it at a small flow rate and uniform speed. The standard is: by visual observation, the sprayed solution should drop on the optical fiber sensing structure in the form of mist and evaporate quickly without converging water droplets;

[0102] S33: Observe the spraying effect, observe whether there is a MXene film in a specific area of ​​the surface through a metallographic microscope, and measure the thickness with a step profiler.

[0103] Example 2

[0104] This embodiment provides an optical fiber dislocation type refractive index sensor based on MXene spray transfer, which is distributed with an introduction single-mode optical fiber 1, an introduction coreless optical fiber 2, a multimode optical fiber, an extraction coreless optical fiber 5, an extraction single-mode optical fiber 6 and MXene material according to the propagation direction of light; the introduction coreless optical fiber and the extraction coreless optical fiber are connected to the multimode optical fiber by dislocation fusion splicing;

[0105] The multimode optical fiber comprises a staggered multimode optical fiber cladding 3 and a staggered multimode optical fiber core 4;

[0106] The MXene material is coated on the surface of the introduced coreless optical fiber 2, the dislocated multimode optical fiber cladding 3 and the lead-out coreless optical fiber 5;

[0107] The introduced single-mode optical fiber 1 is connected to the introduced coreless optical fiber 2; the introduced coreless optical fiber 2 is connected to the offset multimode optical fiber cladding 3; the offset multimode optical fiber cladding 3 is connected to the lead-out coreless optical fiber 5, and the lead-out coreless optical fiber 5 is connected to the lead-out single-mode optical fiber 6; the introduced coreless optical fiber 2, the multimode optical fiber, and the lead-out coreless optical fiber 5 are connected to the lead-out single-mode optical fiber 6; the offset multimode optical fiber cladding 3 is connected to the offset multimode optical fiber core 4; the multimode optical fiber is connected to the 7MXene material.

[0108] The fusion splicing method between the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 is alignment fusion splicing.

[0109] The fusion splicing method between the lead-out coreless optical fiber 5 and the lead-out single-mode optical fiber 6 is alignment fusion splicing.

[0110] The introduction single-mode optical fiber 1 is used to introduce a light source.

[0111] The coreless optical fiber 2 is introduced as a light beam expander to excite the cladding mode.

[0112] The dislocated multimode optical fiber cladding 3 and the dislocated multimode optical fiber core 4 excite the multimode interference effect of the multimode optical fiber through the dislocated structure.

[0113] The lead-out coreless optical fiber 5 is a mode mixer, which plays the role of mode mixing and uniform distribution, thereby improving the coupling efficiency of the interference mode.

[0114] The lead-out single-mode optical fiber 6 is the output of light for subsequent receiving of optical signals.

[0115] The MXene material is a high refractive index sensitive material, which increases the refractive index detection sensitivity of the sensor and enhances the stability of the dislocation sensing structure.

[0116] An optical fiber dislocation refractive index sensor based on MXene spray transfer and a manufacturing method thereof, comprising the following steps:

[0117] S1: Make as Figure 1The multimode optical fiber misalignment structure shown;

[0118] The specific production of the dislocation structure includes the following steps:

[0119] S11: using a fiber pliers to partially strip the coating of the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2, and then fixing the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 with a fiber clamp;

[0120] S12: using an electric fiber cleaver to cut the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 to obtain a flat end face;

[0121] S13: using an optical fiber fusion splicer to align and discharge-fusion-splice the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2;

[0122] S14: Using an optical fiber fusion splicer to perform staggered fusion splicing of the multimode optical fiber and the introduced coreless optical fiber 1;

[0123] At the same time, the other side of the multimode optical fiber also carries out offset displacement welding by leading out the coreless optical fiber 5 in the opposite direction;

[0124] S15: Finally, use a fiber fusion splicer to align and discharge-fusion-splice the lead-out coreless optical fiber 5 and the lead-out single-mode optical fiber 6;

[0125] In one embodiment of the present invention, the length of the coreless optical fiber and the multimode optical fiber is 0.8-1.2 cm.

[0126] In one embodiment of the present invention, the offset welding displacement in step S14 is 62.5 μm, the discharge mode adopted is the multimode fiber fusion mode, the discharge intensity is set to 20 bits, and the discharge time is set to 1100 ms.

[0127] S2: Preparation of Ti3C2Tx MXene dispersion;

[0128] S21: adding 0.8 g of LiF to 10 mL of 9 mol / L hydrochloric acid, stirring for 5 min to allow LiF to fully react with the hydrochloric acid, as an etching agent for the reaction system;

[0129] S22: 1.1 g of Ti3AlC2 MAX powder was slowly added to the etchant (the addition time was more than 10 min), and the system was reacted at 40° C. for 45 h to obtain a reaction mixture;

[0130] S23: washing the reaction mixture by centrifugation with deionized water for 4 times at a centrifugal speed of 3250 rpm until the pH value of the supernatant is greater than 6;

[0131] S24: vacuum filtering the product on a porous polytetrafluoroethylene membrane to obtain a two-layer cake-like slurry and separating the slurry Ti3C2Tx from the solid (Ti3AlC2 that is not completely etched);

[0132] S25: 0.11 g Ti3C2Tx slurry was added to 100 mL deionized water or ethanol and ultrasonicated in an ice water bath for 55 min;

[0133] S26: The dispersion is then centrifuged at 3750 rpm for 30 min to remove the multi-layer MXene aggregates, thereby obtaining a MXene dispersion, which is stored in a reagent bottle for later use;

[0134] Step 3: Transfer MXene by spraying process;

[0135] S31: Fix the optical fiber sensing structure on a glass slide, place it on a hot plate, and set the temperature to 100° C. Heating is performed to accelerate the evaporation of the spray liquid and prevent the solution from gathering into water droplets;

[0136] S32: Pour the prepared MXene dispersion into the spray gun and spray it at a small flow rate and uniform speed. The standard is: by visual observation, the sprayed solution should drop on the optical fiber sensing structure in the form of mist and evaporate quickly without converging water droplets;

[0137] S33: Observe the spraying effect, observe whether there is a MXene film in a specific area of ​​the surface through a metallographic microscope, and measure the thickness with a step profiler.

[0138] Example 3

[0139] This embodiment provides an optical fiber dislocation type refractive index sensor based on MXene spray transfer, which is distributed according to the propagation direction of light with an introduction single-mode optical fiber 1, an introduction coreless optical fiber 2, a multimode optical fiber, an extraction coreless optical fiber 5, an extraction single-mode optical fiber 6, and a MXene material layer formed in a MXene material coating area 7; the introduction coreless optical fiber 2 and the extraction coreless optical fiber 5 are connected to the multimode optical fiber by dislocation fusion splicing;

[0140] The multimode optical fiber comprises a staggered multimode optical fiber cladding 3 and a staggered multimode optical fiber core 4;

[0141] The MXene material is coated on the surface of the introduced coreless optical fiber 2, the dislocated multimode optical fiber cladding 3 and the lead-out coreless optical fiber 5;

[0142] The introduced single-mode optical fiber 1 is connected to the introduced coreless optical fiber 2; the introduced coreless optical fiber 2 is connected to the offset multimode optical fiber cladding 3; the offset multimode optical fiber cladding 3 is connected to the lead-out coreless optical fiber 5, and the lead-out coreless optical fiber 5 is connected to the lead-out single-mode optical fiber 6; the introduced coreless optical fiber 2, the multimode optical fiber, and the lead-out coreless optical fiber 5 are connected to the lead-out single-mode optical fiber 6; the offset multimode optical fiber cladding 3 is connected to the offset multimode optical fiber core 4; the multimode optical fiber is connected to the MXene material.

[0143] The introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 are aligned and fused.

[0144] The fusion splicing method between the lead-out coreless optical fiber 5 and the lead-out single-mode optical fiber 6 is alignment fusion splicing.

[0145] The introduction single-mode optical fiber 1 is used to introduce a light source.

[0146] The coreless optical fiber 2 is introduced as a light beam expander to excite the cladding mode.

[0147] The dislocated multimode optical fiber cladding 3 and the dislocated multimode optical fiber core 4 excite the multimode interference effect of the multimode optical fiber through the dislocated structure.

[0148] The lead-out coreless optical fiber 5 is a mode mixer, which plays the role of mode mixing and uniform distribution, thereby improving the coupling efficiency of the interference mode.

[0149] The lead-out single-mode optical fiber 6 is the output of light for subsequent receiving of optical signals.

[0150] The MXene material layer is a high refractive index sensitive material, which increases the refractive index detection sensitivity of the sensor and enhances the stability of the dislocation sensing structure.

[0151] An optical fiber dislocation refractive index sensor based on MXene spray transfer and a manufacturing method thereof, comprising the following steps:

[0152] S1: Make as Figure 1 The multimode optical fiber misalignment structure shown;

[0153] The specific production of the dislocation structure includes the following steps:

[0154] S11: using a fiber pliers to partially strip the coating of the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2, and then fixing the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 with a fiber clamp;

[0155] S12: using an electric fiber cleaver to cut the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2 to obtain a flat end face;

[0156] S13: using an optical fiber fusion splicer to align and discharge-fusion-splice the introduced single-mode optical fiber 1 and the introduced coreless optical fiber 2;

[0157] S14: Using an optical fiber fusion splicer to perform staggered fusion splicing of the multimode optical fiber and the introduced coreless optical fiber 1;

[0158] At the same time, the other side of the multimode optical fiber also carries out offset displacement welding by leading out the coreless optical fiber 5 in the opposite direction;

[0159] S15: Finally, use a fiber fusion splicer to align and discharge-fusion-splice the lead-out coreless optical fiber 5 and the lead-out single-mode optical fiber 6;

[0160] In one embodiment of the present invention, the length of the coreless optical fiber and the multimode optical fiber is 0.8 cm, and may also be 1 cm or 1.2 cm.

[0161] In one embodiment of the present invention, the offset welding displacement in step S14 is 62.5 μm. Figure 1 As shown; the discharge mode adopted is the multimode fiber fusion mode, the discharge intensity is set to 20 bits, and the discharge time is set to 1200ms.

[0162] S2: Preparation of Ti3C2Tx MXene dispersion;

[0163] S21: 0.9 g of LiF was added to 11 mL of 10 mol / L hydrochloric acid and stirred for 6 min to allow the LiF and hydrochloric acid to react fully as an etching agent in the reaction system;

[0164] S22: 1.2 g of Ti3AlC2 MAX powder was slowly added to the etchant (the addition time was more than 10 min). The system was reacted at 45°C for 50 h to obtain a reaction mixture;

[0165] S23: washing the reaction mixture by centrifugation with deionized water for 5 times at a centrifugal speed of 3500 rpm until the pH value of the supernatant is greater than 6;

[0166] S24: vacuum filtering the product on a porous polytetrafluoroethylene membrane to obtain a two-layer cake-like slurry and separating the slurry (Ti3C2Tx) from the solid (Ti3AlC2 that is not completely etched);

[0167] S25: 0.12 g of Ti3C2Tx slurry was added to 110 mL of deionized water or ethanol and ultrasonicated in an ice water bath for 1 h;

[0168] S26: The dispersion is then centrifuged at 4000 rpm for 35 min to remove the multi-layer MXene aggregates to obtain a MXene dispersion, which is stored in a reagent bottle for later use;

[0169] Step 3: Transfer MXene by spraying process;

[0170] S31: Fix the optical fiber sensing structure on a glass slide, place it on a hot plate, and set the temperature to 110° C. Heating is performed to accelerate the evaporation of the spraying liquid and prevent the solution from gathering into water droplets;

[0171] S32: Pour the prepared MXene dispersion into the spray gun and spray it at a small flow rate and uniform speed. The standard is: by visual observation, the sprayed solution should drop on the optical fiber sensing structure in the form of mist and evaporate quickly without converging water droplets;

[0172] S33: Observe the spraying effect, observe whether there is a MXene film in a specific area of ​​the surface through a metallographic microscope, and measure the thickness with a step profiler.

[0173] It is particularly noted that in step S31, the heating time is about 5 minutes to ensure that the temperature of the optical fiber sensing structure is stable. In step S32, the spraying time is controlled according to the rate, and the same rate is maintained. The recommended initial spraying time is 5 to 10 minutes. After multiple sprayings, the actual film thickness is measured and the subsequent spraying time is adjusted to achieve the required thickness; in addition, during the operation, ensure that the distance between the spray gun and the optical fiber sensing structure is maintained between 10-15 cm to obtain the best spraying effect.

[0174] Compared with ordinary fiber optic sensors, the fiber optic dislocation refractive index sensor based on MXene spray transfer can greatly reduce the volume of the sensing system while achieving a stable sensing structure, effectively improving the system's solution refractive index detection sensitivity, and has the advantages of simple structure, convenient preparation, and small size. At the same time, the fiber optic solution sensing system has good embeddability and stability, and can be deployed in various harsh liquid environments. It is of great significance to improve the performance of the fiber optic liquid sensing system and expand the refractive index detection coverage of the fiber optic sensing system.

[0175] The embodiment of the present invention mainly utilizes the core offset caused by the large misalignment splicing of multimode optical fiber and single-mode optical fiber, which leads to the cladding mode excited by the mode field mismatch. These cladding modes form a stronger evanescent field on the surface of the optical fiber, and the interaction with the external environment is more significant. And by utilizing the refractive index response law of the MXene coating to the external solution, the refractive index sensitivity of the liquid detection device is effectively improved through misalignment splicing and MXene materials. Due to the existence of the misaligned splicing structure coated with MXene, the effect of the light field and the liquid medium can be effectively increased.

[0176] like Figure 2As shown, the working process of the optical fiber dislocation refractive index sensor based on MXene spray transfer in an embodiment of the present invention is: the sensing structure is placed in the detection liquid, and the signal light output by the broadband light source with a working band of 1500-1600nm is separated by introducing a single-mode optical fiber and a coreless optical fiber, and reaches the dislocation multimode optical fiber cladding 3, the dislocation multimode optical fiber core 4 and the MXene coating area 7 respectively, and after the evanescent wave light signal of the cladding and the core light signal and the liquid medium in this area act together, it is coupled to the lead-out coreless optical fiber to cause mode mixing and realize uniform distribution of the mode, and finally generates an interference spectrum output in the lead-out single-mode optical fiber.

[0177] Unless otherwise specified, the models of the components in the embodiments of the present invention are not limited, and any device that can perform the above functions may be used.

[0178] Those skilled in the art will appreciate that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0179] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical fiber dislocation refractive index sensor based on MXene spray transfer, characterized in that: In the propagation direction of light, there are an introduction single-mode optical fiber, an introduction coreless optical fiber, a multimode optical fiber, an extraction coreless optical fiber, an extraction single-mode optical fiber and a MXene material layer; the introduction coreless optical fiber and the extraction coreless optical fiber are connected to the multimode optical fiber by offset fusion splicing; The multimode optical fiber comprises a staggered multimode optical fiber cladding and a staggered multimode optical fiber core; The MXene material layer is coated on the surface of the introduced coreless optical fiber, the dislocated multimode optical fiber cladding, and the led-out coreless optical fiber; The introduced single-mode optical fiber is connected to the introduced coreless optical fiber; the introduced coreless optical fiber is connected to the offset multimode optical fiber cladding; the offset multimode optical fiber cladding is connected to the lead-out coreless optical fiber, and the lead-out coreless optical fiber is connected to the lead-out single-mode optical fiber; the introduced coreless optical fiber, multimode optical fiber, and lead-out coreless optical fiber are connected to the lead-out single-mode optical fiber; the offset multimode optical fiber cladding is connected to the offset multimode optical fiber core; the multimode optical fiber is connected to the MXene material layer.

2. The optical fiber dislocation refractive index sensor based on MXene spray transfer according to claim 1, characterized in that: The fusion splicing method between the introduced single-mode optical fiber and the introduced coreless optical fiber is alignment fusion splicing.

3. The optical fiber dislocation refractive index sensor based on MXene spray transfer according to claim 1, characterized in that: The fusion splicing method between the lead-out coreless optical fiber and the lead-out single-mode optical fiber is alignment fusion splicing.

4. The optical fiber dislocation refractive index sensor based on MXene spray transfer according to claim 1, characterized in that: The introduced single-mode optical fiber is used to introduce a light source; the introduced coreless optical fiber is used as a light beam expander, and the cladding mode is excited and output to a multi-mode optical fiber.

5. The optical fiber dislocation refractive index sensor based on MXene spray transfer according to claim 1, characterized in that: The dislocated multimode optical fiber cladding and the dislocated multimode optical fiber core excite the multimode interference effect of the multimode optical fiber through the dislocated structure.

6. The optical fiber dislocation refractive index sensor based on MXene spray transfer according to claim 5, characterized in that: The single-mode optical fiber outputs an optical signal for subsequent reception, and the refractive index of the MXene material layer ranges from 1.68 to 2.

5.

7. A method for preparing an optical fiber dislocation refractive index sensor based on MXene spray transfer, characterized in that: The following steps are involved: S1: Making a multimode optical fiber staggered structure, specifically including the following steps: S11: stripping the coating of the introduced single-mode optical fiber and the introduced coreless optical fiber, and then fixing the introduced single-mode optical fiber and the introduced coreless optical fiber; S12: cutting the introduced single-mode optical fiber and the introduced coreless optical fiber to obtain a flat end face; S13: performing aligned discharge welding on the introduced single-mode optical fiber and the introduced coreless optical fiber; S14: performing staggered fusion splicing on one side of the multimode optical fiber and the lead-in coreless optical fiber, and performing staggered fusion splicing on the other side of the multimode optical fiber and the lead-out coreless optical fiber in the opposite direction; S15: aligning and discharging the lead-out coreless optical fiber and the lead-out single-mode optical fiber for welding; So far, from S11 to S15, a multimode optical fiber dislocation structure is prepared; S2: Preparation of Ti3C2Tx MXene dispersion; S3: Spraying process to transfer MXene dispersion; S31: fixing the multimode optical fiber dislocation structure on a glass slide, and then placing the glass slide on a hot stage for heating; S32: spraying the MXene dispersion onto the multimode optical fiber dislocation structure at a uniform speed; S33: Observe whether there is a MXene film in a specific area of ​​the surface and measure the thickness of the MXene film; The uniform speed spraying in S32 and the measurement of the thickness of the MXene film in S33 specifically control the spraying time according to the rate, maintain the same rate and the initial spraying time is 5 to 10 minutes; after multiple spraying, measure the actual film thickness and adjust the subsequent spraying time to achieve the desired thickness.

8. The method for preparing a fiber-optic dislocation refractive index sensor based on MXene spray transfer according to claim 7, characterized in that: During the uniform speed spraying process, in order to obtain the best spraying effect, it is necessary to ensure that the distance between the spray gun and the optical fiber sensing structure is maintained between 10 and 15 cm.

9. The method for preparing a fiber-optic dislocation refractive index sensor based on MXene spray transfer according to claim 8, characterized in that: The length of the single-mode optical fiber, coreless optical fiber, and multi-mode optical fiber described in S11, S12, S13, S14, and S15 is 0.8 to 1.2 cm.

10. The method for preparing a fiber-optic dislocation refractive index sensor based on MXene spray transfer according to claim 9, characterized in that: S14 The discharge mode used in the offset welding is a multimode optical fiber fusion splicing mode and the displacement distance of the offset welding is 60 to 65 μm.

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