A 1.1 mu m near-infrared band flexible optical fiber and a preparation method and application thereof

Abstract

The application discloses a 1.1-micron near-infrared band flexible optical fiber and a preparation method and application thereof. The optical fiber comprises a core and a cladding structure, the core comprises Nd x Sc 2‑x Si2O7 (0.01<=x<=0.07) fluorescent powder and a first transparent elastomer material, and the cladding comprises a second transparent elastomer material. Raw materials are mixed in a stoichiometric ratio, and a reaction is carried out at a high temperature. After cooling, the Nd:Sc2Si2O7 fluorescent powder is taken out and ground. The fluorescent powder is mixed with a high-molecular pre-polymer, stirred and defoamed to obtain a core precursor solution. The core precursor solution is injected into a mold for solidification, and the core is obtained after demolding. Then, the cladding is coated on the core and solidified to form a flexible optical fiber with a core-cladding structure. The method is controllable, and can effectively ensure uniform dispersion of the fluorescent powder. The obtained flexible optical fiber efficiently emits a 1.1-micron near-infrared band, has good flexibility, and is suitable for wearable devices, flexible display, biomedical sensing and near-infrared lighting and the like.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials and flexible optical fiber technology, specifically relating to a flexible optical fiber whose emission spectrum can effectively cover the 1.1 µm band and its preparation method. Background Technology

[0002] The rapid development of flexible optoelectronic devices such as wearable biosensors, implantable phototherapy, and minimally invasive endoscopic imaging has placed stringent demands on near-infrared light sources, requiring miniaturization, flexibility, and biocompatibility. Particularly for the 1.1 µm band, a specific wavelength within the optical window of biological tissues, there is an urgent need for a flexible light source that can be stably operated even when bent. However, existing technologies cannot directly meet this requirement: traditional 1.1 µm lasers or LEDs are rigid discrete devices that cannot be bent or implanted; while solutions using ordinary power transmission fibers coupled to discrete light sources suffer from system complexity, low coupling efficiency, and fragile interfaces, and cannot achieve distributed layout and terminal emission of the light source. To fundamentally solve these problems, integrating fluorescent materials directly into the fiber core to construct an integrated flexible fluorescent fiber that combines emission and waveguide transmission characteristics has become an ideal solution. Such devices can output the desired wavelength at any bent end of the fiber through remote pumping, making them particularly suitable for the complex environment within organisms. However, the implementation of this solution highly depends on core materials capable of achieving efficient emission in the 1.1 µm band.

[0003] Currently, there are limitations to the material systems used to achieve luminescence in this wavelength range. Rare earth ions (such as Yb) 3+ 、Nd 3+ Traditional materials doped with Cr have emission spectra concentrated in the 980–1060 nm range, making it difficult to effectively cover the 1.1 µm band; while transition metals (Cr... 3+ Although materials doped with Bi ions from Group I or main groups can achieve broadband near-infrared emission, they generally suffer from problems such as low luminous efficiency, short excited-state lifetime, and the need for specific excitation wavelengths (such as ultraviolet light) or harsh preparation conditions (such as reducing atmosphere), which limit their application in high-brightness, integrated devices.

[0004] Currently, the solid-state form of some high-performance phosphors limits their direct application, failing to meet the urgent needs of fields such as biomedicine for flexible, miniaturized, and integrable light sources. To realize their application value, these powder materials must be constructed into practical light source devices capable of effectively generating, collecting, and extracting light energy. Flexible optical fibers are an ideal carrier for this purpose, serving as both light waveguides and light emitters. However, for micron-sized inorganic powders, the fabrication of flexible optical fibers generally faces problems such as uneven dispersion and easy sedimentation and agglomeration in viscous precursors, as well as uneven light emission and severe light scattering after fiber formation. Therefore, based on the high-performance Nd:Sc2Si2O7 near-infrared phosphor, developing a matching method that can achieve highly uniform dispersion of the phosphor and form it into flexible optical fibers with good optical quality is key to transforming this material from a powder form into a practical optical fiber device, and is of great significance for promoting its practical application in cutting-edge fields such as flexible optoelectronics and bio-integrated optics. Summary of the Invention

[0005] The purpose of this invention is to provide a 1.1 µm near-infrared flexible optical fiber and its fabrication method. This method aims to overcome the technical problems of high-performance Nd:Sc2Si2O7 phosphors being difficult to apply directly due to their powder morphology, and the uneven powder dispersion and easy agglomeration and sedimentation leading to optical fiber deterioration during composite fabrication of flexible optical fibers. It provides a process-controllable method for fabricating flexible optical fibers that achieves highly uniform phosphor dispersion and stable composite fabrication.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A 1.1 µm near-infrared flexible optical fiber comprises a core and a cladding structure, wherein the core comprises a phosphor and a first transparent elastomer material, and the phosphor has the general chemical formula Nd. x Sc 2-x Si2O7, where x is Nd 3+ The doping molar fraction of ions, and 0.01≤x≤0.07, the cladding comprises a second transparent elastomer material.

[0008] The refractive index of the second transparent elastomer material is lower than that of the first transparent elastomer material.

[0009] The first transparent elastomer material is selected from one or more of silicone elastomers, transparent polyurethane elastomers, acrylate polymers, or polycarbonates.

[0010] Preferably, the first transparent elastomer material is a phenyl-modified organosilicon elastomer.

[0011] More preferably, the first transparent elastomer material is methylphenyl silicone rubber.

[0012] The phosphor is uniformly dispersed in the first transparent elastomer material in the form of particles.

[0013] The mass ratio of phosphor to the first transparent elastomer material in the fiber core is 1:10 to 1:100.

[0014] The second transparent elastomer material is selected from one or more of silicone elastomers, fluoropolymers, or modified materials thereof.

[0015] Preferably, the second transparent elastomer material is selected from one or more of polydimethylsiloxane (PDMS), methyl silicone rubber (MSR), or fluorinated polysiloxane (FPS).

[0016] Both the first and second transparent elastomer materials mentioned above are transparent elastomer materials that can be cross-linked or cured at a temperature below 120°C.

[0017] The amount of the second transparent elastomer material used in the flexible optical fiber is 0.2~2 g.

[0018] The method for fabricating the aforementioned 1.1 µm near-infrared flexible optical fiber includes the following steps: (1) According to the general chemical formula Nd x Sc 2-x The stoichiometric ratio of raw materials containing neodymium, scandium and silicon compounds was used to prepare Si2O7. A flux was added, and the mixture was ground and mixed evenly. The mixture was then sieved. (2) The sieve material obtained in step (1) is placed in an air atmosphere and subjected to high-temperature sintering treatment. After cooling to room temperature, it is taken out and ground to obtain the Nd. x Sc 2-x Si2O7 phosphor.

[0019] (3) Mix the phosphor described in step (2) with the first transparent elastomer material evenly to form a fiber core precursor solution, and perform degassing treatment; (4) The fiber core precursor solution obtained in step (3) is injected into a tubular mold for thermosetting, and then demolded to obtain a flexible fiber core; (5) The second transparent elastomer precursor is coated on the outer surface of the flexible fiber core obtained in step (4) by spin coating, and then thermosetting is performed to form a cladding to obtain a flexible optical fiber with a core-cladding structure.

[0020] In step (1), the raw materials include neodymium-containing compounds, scandium-containing compounds, and silicon-containing compounds. The neodymium-containing compounds are selected from neodymium oxide or neodymium carbonate, the scandium-containing compounds are selected from scandium oxide or scandium carbonate, and the silicon-containing compounds are selected from silicon dioxide. The flux is selected from at least one or more of lithium fluoride, sodium fluoride, barium fluoride, boric acid, and sodium chloride. The total amount of flux added is 0.5 wt.% to 10 wt.% of the total mass of the main raw materials. The grinding time is 10 to 60 minutes.

[0021] In step (2), the sintering process is carried out in an air atmosphere, the heating rate is 5~20 ℃ / min, the sintering temperature is 1300~1600 ℃, and the holding time is 2~8 hours.

[0022] In step (3), the degassing process is carried out under vacuum conditions and the settling time is 1 to 3 hours.

[0023] In step (4), the curing temperature is 60~100 ℃ and the curing time is 30~90 minutes.

[0024] In step (5), the spin coating process includes two spin-spinning operations, and the two spin-spinning directions are opposite to improve the thickness uniformity of the cladding along the fiber core axis. The spin coating speed is 800~1200 r / min, the curing temperature is 60~100 ℃, and the curing time is 30~90 minutes.

[0025] The 1.1 µm near-infrared flexible optical fiber prepared by the above method is suitable for applications such as wearable devices, flexible displays, biomedical sensing, and near-infrared lighting.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Transforming Nd:Sc2Si2O7 phosphor from its inherent powder form into a flexible optical fiber structure enables the material to be directly applied in cutting-edge fields requiring flexibility in the form of integrated light source devices.

[0027] 2. By using a composite dispersion process involving grinding, sieving, and high-speed stirring, the problem of easy agglomeration and sedimentation of micron-sized inorganic powders in viscous polymer precursors is effectively overcome, providing a reliable method for achieving highly uniform distribution of phosphors in the fiber core.

[0028] 3. The core-cladding structure uses phosphor and OE as the fiber core and low-refractive-index PDMS as the cladding, which forms an effective waveguide interface optically and ensures the overall flexibility and bending performance of the optical fiber mechanically.

[0029] 4. The preparation process adopts low-temperature curing technology, which avoids the damage of high-temperature processes to phosphors, thereby maximizing the preservation of the crystal structure and luminescence properties of Nd:Sc2Si2O7 phosphors.

[0030] 5. It provides practical device solutions for Nd:Sc2Si2O7 phosphors in fields such as flexible biomedicine and wearable sensing that require miniaturization and shape adaptation of light sources. Attached Figure Description

[0031] Figure 1 The Sc prepared in Example 1 1.99 Si2O7:0.01Nd 3+ X-ray powder diffraction pattern of phosphor.

[0032] Figure 2 The Sc prepared in Example 1 1.99 Si2O7:0.01Nd 3+ Photograph of phosphor-composite flexible optical fiber under natural light.

[0033] Figure 3 Nd prepared in Examples 1 to 3 x Sc 2-x Photoluminescence spectrum of Si2O7 phosphor under 808 nm laser excitation.

[0034] Figure 4 Nd prepared in Examples 1 to 3 x Sc 2-x Photoluminescence spectrum of Si2O7 phosphor composite flexible optical fiber under 808 nm laser excitation. Detailed Implementation

[0035] To better understand the present invention, the following embodiments are provided for further explanation. However, the described embodiments are merely some, not all, of the embodiments of the present invention, and the scope of protection claimed by the present invention is not limited thereto. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] Example 1 The phosphor composition (S1) in this embodiment is: chemical composition Nd 0.01 Sc 1.99Si₂O₇. The raw materials selected were neodymium carbonate, scandium oxide, and silicon dioxide with a purity of 99.99%. The main raw materials were weighed according to stoichiometric ratio. 10 wt.% of a composite flux (composed of sodium chloride and boric acid in a 1:1 mass ratio) was added to the main raw materials. The mixture was then ground in a mortar for 30 minutes, passed through a 250-mesh sieve, and subsequently transferred to a dense corundum crucible. The temperature was increased to 1300℃ at a heating rate of 20℃ / min and sintered for 8 hours. The furnace was then cooled to room temperature. The sample was removed, ground, and passed through a 650-mesh sieve to obtain Sc. 1.99 Si2O7:0.01Nd 3+ Fluorescent powder.

[0037] Sc 1.99 Si2O7:0.01Nd 3+ Phosphor and methylphenyl silicone rubber (optical encapsulant OE 6550) were mixed at a mass ratio of 1:100, stirred evenly, and then placed in a vacuum drying oven for 1 hour to obtain a uniform, bubble-free fiber core precursor solution. The fiber core precursor solution was injected into a tubular mold and cured at 60°C for 90 minutes. The mold was then removed to obtain a flexible fiber core. The surface of the flexible fiber core was dipped in PDMS solution, removed, and rotated clockwise for 30 seconds and counterclockwise for 10 seconds at 800 r / min. This process was repeated, and by controlling the spin coating process parameters, a uniform PDMS cladding with a thickness of approximately 50 µm could be obtained. The precursor flexible optical fiber was then cured at 60°C for 90 minutes to obtain a composite Sc 1.99 Si2O7:0.01Nd 3+ Flexible optical fiber with phosphor.

[0038] The XRD patterns of the phosphors were measured using an Aeris powder X-ray diffractometer (PANalytical Corporation, Netherlands); the photoluminescence spectra of the phosphors were measured using a Zolix Omin 3007 spectrometer (Beijing, China), with an 808 nm laser as the excitation source; and the fluorescence spectra of the flexible optical fiber were measured using a near-infrared fiber optic spectrometer (Ocean Optics, Shanghai, China), with an 808 nm laser as the excitation source.

[0039] Sc prepared in Example 1 1.99 Si2O7:0.01Nd 3+ A comparison of the X-ray powder diffraction pattern of the phosphor and the standard card (ICDD 96-152-8086) is shown below. Figure 1 As shown, XRD pattern analysis indicates that the obtained sample phase is Sc2Si2O7, belonging to the monoclinic crystal system, and Nd 3+Ion doping does not introduce other phases or impurities. For example... Figure 3 As shown, the phosphor prepared in Example 1 4 F 3 / 2 → 4 I 11 / 2 The main emission peak corresponding to the transition is centered at 1089 nm, with a full width at half maximum (FWHM) of 30 nm and a fluorescence branching ratio as high as 74.7%. Flexible optical fiber prepared in Example 1. 4 F 3 / 2 → 4 I 11 / 2 The emission peak corresponding to the transition is split, with split peaks at 1065 nm, 1079 nm, 1089 nm, and 1115 nm, respectively. The peak intensity at 1079 nm is the highest, with a full width at half maximum (FWHM) of 21 nm. This transition covers the spectral range from 970 nm to 1230 nm. Figure 4 As shown. Figure 2 The image shows the flexible optical fiber prepared in Example 1 under natural light. The flexible optical fiber is easy to bend and knot, which proves that the flexible optical fiber has good mechanical flexibility and deformability, and has good potential in the field of wearable devices.

[0040] Example 2 The phosphor composition (S2) in this embodiment is: chemical composition Nd 0.06 Sc 1.94 Si₂O₇. The raw materials selected were neodymium oxide, scandium carbonate, and silicon dioxide with a purity of 99.99%. The main raw materials were weighed according to stoichiometric ratio. 5 wt.% of a composite flux (composed of lithium fluoride and sodium fluoride in a 1:1 mass ratio) was added to the main raw materials. The mixture was then ground in a mortar for 10 minutes, passed through a 250-mesh sieve, and subsequently transferred to a dense corundum crucible. The temperature was increased to 1500℃ at a heating rate of 10℃ / min and sintered for 4 hours. The mixture was then cooled to room temperature in the furnace. The sample was removed, ground, and passed through a 650-mesh sieve to obtain Sc. 1.94 Si2O7:0.06Nd 3+ Fluorescent powder.

[0041] Sc 1.94 Si2O7:0.06Nd 3+Phosphor and methylphenyl silicone rubber (optical sealing adhesive OE 6550) were mixed at a mass ratio of 1:50, stirred evenly, and then placed in a vacuum drying oven for 2 hours to obtain a uniform, bubble-free fiber core precursor solution. The fiber core precursor solution was injected into a tubular mold and cured at 80°C for 60 minutes. The mold was then removed to obtain a flexible fiber core. The surface of the flexible fiber core was dipped in MSR solution, removed, and rotated clockwise for 30 seconds and counterclockwise for 10 seconds at 1000 r / min. The flexible fiber core was then dipped in PDMS solution, removed, and rotated counterclockwise for 30 seconds and clockwise for 10 seconds at 1000 r / min. By controlling the above spin coating process parameters, a uniform PDMS cladding with a thickness of approximately 50 µm could be obtained. Then, the precursor flexible optical fiber was cured at 80°C for 60 minutes to obtain a composite Sc 1.94 Si2O7:0.06Nd 3+ Flexible optical fiber with phosphor.

[0042] The XRD patterns of the phosphors were measured using an Aeris powder X-ray diffractometer (PANalytical Corporation, Netherlands); the photoluminescence spectra of the phosphors were measured using a Zolix Omin 3007 spectrometer (Beijing, China), with an 808 nm laser as the excitation source; and the fluorescence spectra of the flexible optical fiber were measured using a near-infrared fiber optic spectrometer (Ocean Optics, Shanghai, China), with an 808 nm laser as the excitation source.

[0043] Sc prepared in Example 2 1.94 Si2O7:0.06Nd 3+ fluorescent powder 4 F 3 / 2 → 4 I 11 / 2 The main emission peak corresponding to the transition is centered at 1089 nm, with a full width at half maximum (FWHM) of 30 nm and a fluorescence branching ratio as high as 73.4%. Figure 3 As shown. Flexible optical fiber prepared in Example 2. 4 F 3 / 2 → 4 I 11 / 2 The emission peak corresponding to the transition is split, with split peaks at 1065 nm, 1079 nm, 1089 nm, and 1115 nm, respectively. The peak intensity at 1079 nm is the highest, with a full width at half maximum (FWHM) of 20 nm. This transition covers the spectral range from 970 nm to 1230 nm. Figure 4 As shown.

[0044] This spectral change primarily stems from a fundamental shift in the testing system and material morphology. Firstly, phosphor testing involves near-surface detection, where the signal is strongly averaged by multiple scattering between particles. Flexible optical fibers, employing an end-pump-end-probe waveguide operating mode, utilize pump light propagating within the fiber core and the waveguide's directional collection of fluorescence to create a highly spatially selective signal extraction mechanism, effectively distinguishing the characteristic differences of luminescent centers in different micro-regions. Secondly, the transformation of phosphors from a loosely packed state to a polymer-encapsulated composite waveguide restructures their physicochemical environment. The anisotropic microscopic shrinkage stress generated during polymer curing acts on the dispersed phosphor particles, leading to Nd: 3+ The local crystal field where the ion is located undergoes a non-uniform, minute distortion. This perturbation causes... 4 F 3 / 2 and 4 I 11 / 2 Stark splitting of the energy level allows characteristic emissions corresponding to different local environments (such as 1079 nm and 1089 nm) to be distinguished and highlighted in the selective collection of the waveguide. The peak intensity at 1079 nm is the highest, indicating that a specific stress environment may favor this energy level transition. This confirms that the phosphor has been successfully transformed into a composite waveguide material tightly bonded to the polymer matrix, forming a functional system with novel spectral characteristics. Flexible fiber structures can, to some extent, overcome the problems of the Nd:Sc2Si2O7 phosphor's morphology being difficult to directly apply, and the uneven powder dispersion and easy agglomeration and sedimentation leading to fiber optical quality degradation during composite fabrication of flexible fibers. This is of great significance for promoting its practical application in cutting-edge fields such as flexible optoelectronics and bio-integrated optics.

[0045] Example 3 The phosphor composition (S3) in this embodiment is: chemical composition Nd 0.07 Sc 1.93 Si₂O₇. The raw materials selected were neodymium oxide, scandium oxide, and silicon dioxide with a purity of 99.99%. The raw materials were weighed according to stoichiometric ratios. 0.5 wt.% of barium fluoride flux was added to the main raw materials, and the mixture was ground in a mortar for 60 min, passed through a 250-mesh sieve, and then transferred to a dense corundum crucible. The temperature was increased to 1600℃ at a heating rate of 5℃ / min and sintered for 2 hours. The mixture was then cooled to room temperature in the furnace, and the sample was removed, ground, and passed through a 650-mesh sieve to obtain Sc. 1.93 Si2O7:0.07Nd 3+ Fluorescent powder.

[0046] Sc 1.93 Si2O7:0.07Nd 3+Phosphor and methylphenyl silicone rubber (optical sealing adhesive OE 6550) were mixed at a mass ratio of 1:10, stirred evenly, and then placed in a vacuum drying oven for 3 hours to obtain a uniform, bubble-free fiber core precursor solution. The fiber core precursor solution was injected into a tubular mold and cured at 100°C for 30 minutes. The mold was then removed to obtain a flexible fiber core. The surface of the flexible fiber core was dipped in FPS solution, removed, and rotated clockwise for 30 seconds and counterclockwise for 10 seconds at 1200 r / min. The flexible fiber core was then dipped in PDMS solution, removed, and rotated counterclockwise for 30 seconds and clockwise for 10 seconds at 1200 r / min. By controlling the above spin coating process parameters, a uniform PDMS cladding with a thickness of approximately 50 µm can be obtained. The precursor flexible optical fiber was then cured at 100°C for 30 minutes to obtain a composite Sc 1.93 Si2O7:0.07Nd 3+ Flexible optical fiber with phosphor.

[0047] The XRD patterns of the phosphors were measured using an Aeris powder X-ray diffractometer (PANalytical Corporation, Netherlands); the photoluminescence spectra of the phosphors were measured using a Zolix Omin 3007 spectrometer (Beijing, China), with an 808 nm laser as the excitation source; and the fluorescence spectra of the flexible optical fiber were measured using a near-infrared fiber optic spectrometer (Ocean Optics, Shanghai, China), with an 808 nm laser as the excitation source.

[0048] Phosphor prepared in Example 3 4 F 3 / 2 → 4 I 11 / 2 The main emission peak corresponding to the transition is centered at 1089 nm, with a full width at half maximum (FWHM) of 30 nm and a fluorescence branching ratio of 76.4%. Figure 3 As shown. Flexible optical fiber prepared in Example 3. 4 F 3 / 2 → 4 I 11 / 2 The emission peak corresponding to the transition is split, with split peaks at 1065 nm, 1079 nm, 1089 nm, and 1115 nm, respectively. The peak intensity at 1079 nm is the highest, with a full width at half maximum (FWHM) of 22 nm. This transition covers the spectral range from 970 nm to 1230 nm. Figure 4 As shown.

[0049] The above embodiments demonstrate that the flexible optical fiber provided by this invention can effectively generate and transmit near-infrared light in the 1.1 µm band, successfully transforming high-performance phosphor materials into directly integrateable flexible light source devices. This has significant value in promoting the miniaturization and flexible application of light sources in this band. The fabrication method described in this invention is process-controllable and has good repeatability, providing a feasible path for the fabrication and large-scale production of this type of composite functional optical fiber.

[0050] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A 1.1 µm near-infrared flexible optical fiber, characterized in that: It comprises a core and a cladding structure, wherein the core comprises a phosphor and a first transparent elastomer material, the phosphor having the general chemical formula Nd. x Sc 2-x Si2O7, where x is Nd 3+ The doping molar fraction of ions, and 0.01≤x≤0.07, the cladding comprises a second transparent elastomer material.

2. The flexible optical fiber according to claim 1, characterized in that: The first transparent elastomer material is selected from one or more of silicone elastomers, transparent polyurethane elastomers, acrylate polymers, or polycarbonates. The second transparent elastomer material is selected from one or more of silicone elastomers, fluoropolymers, or modified materials thereof; The refractive index of the second transparent elastomer material is lower than that of the first transparent elastomer material.

3. The flexible optical fiber according to claim 1, characterized in that: The mass ratio of phosphor to first transparent elastomer material in the fiber core is 1:10 to 1:

100.

4. The method for fabricating the 1.1 µm near-infrared flexible optical fiber according to claim 1, characterized in that: Includes the following steps: (1) According to the general chemical formula Nd x Sc 2-x The stoichiometric ratio of raw materials containing neodymium, scandium and silicon compounds was used to prepare Si2O7. A flux was added, and the mixture was ground and mixed evenly. The mixture was then sieved. (2) The sieve material obtained in step (1) is placed in an air atmosphere and subjected to high-temperature sintering treatment. After cooling to room temperature, it is taken out and ground to obtain the Nd. x Sc 2-x Si2O7 phosphor; (3) Mix the phosphor described in step (2) with the first transparent elastomer material evenly to form a fiber core precursor solution, and perform degassing treatment; (4) The fiber core precursor solution obtained in step (3) is injected into a tubular mold for thermosetting, and then demolded to obtain a flexible fiber core; (5) The second transparent elastomer precursor is coated on the outer surface of the flexible fiber core obtained in step (4) by spin coating, and then thermosetting is performed to form a cladding to obtain a flexible optical fiber with a core-cladding structure.

5. The preparation method according to claim 4, characterized in that: In step (1), The neodymium-containing compound is selected from neodymium oxide or neodymium carbonate; the scandium-containing compound is selected from scandium oxide or scandium carbonate; the silicon-containing compound is selected from silicon dioxide; The flux is selected from at least one or more of lithium fluoride, sodium fluoride, barium fluoride, boric acid, and sodium chloride; The total amount of flux added is 0.5 wt.% to 10 wt.% of the total mass of the main raw materials; the grinding and mixing time is 10 to 60 minutes.

6. The preparation method according to claim 4, characterized in that: In step (2), The heating rate of the sintering process is 5~20℃ / min, the sintering temperature is 1300~1600℃, and the holding time is 2~8 hours.

7. The preparation method according to claim 4, characterized in that: In step (3), The degassing process is carried out under vacuum conditions, and the settling time is 1 to 3 hours.

8. The preparation method according to claim 4, characterized in that: In step (4), The curing temperature is 60~100℃, and the curing time is 30~90 minutes.

9. The preparation method according to claim 4, characterized in that: In step (5), The spin coating operation is performed at a speed of 800~1200 r / min; The curing temperature is 60~100℃, and the curing time is 30~90 minutes.

10. The application of the 1.1 µm near-infrared flexible optical fiber according to any one of claims 1-3 or the 1.1 µm near-infrared flexible optical fiber prepared by the preparation method according to any one of claims 4-9 in wearable devices, flexible displays, biomedical sensing and near-infrared illumination.

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