A photo-cured rare earth ion doped silica glass, its preparation method and application

Abstract

This invention belongs to the field of rare earth ion-doped glass manufacturing technology, specifically disclosing a photocurable rare earth ion-doped silica glass, its preparation method, and its application. The invention first mixes a polyhedral oligomeric silsesquioxane containing acrylic acid groups, an acrylate crosslinking agent, and a photoinitiator to obtain a photosensitive resin matrix; then, a rare earth organic complex is incorporated and mixed uniformly to obtain a rare earth ion-doped silica precursor; next, selective exposure curing is performed using ultraviolet lithography or two-photon direct writing, followed by development; after development, a non-sintering heat treatment is performed to obtain the photocurable rare earth ion-doped silica glass. This invention achieves stable and uniform dispersion of rare earth ions in the photosensitive precursor system, and can complete high-conformity glass conversion at a relatively low temperature, while simultaneously achieving controllable and predictable doping concentration.

Description

Technical Field

[0001] This invention relates to the field of rare earth ion-doped glass manufacturing technology, and in particular to a photocurable rare earth ion-doped silica glass, its preparation method, and its application. Background Technology

[0002] Rare-earth ion-doped glasses, due to their unique 4f energy level structure and efficient photoluminescence properties, have become important optical glass matrix materials, widely used in laser generation, optical temperature sensing, and photonic chips. However, with the miniaturization and on-chip integration of optoelectronics and integrated optical systems, traditional rare-earth-doped glass fabrication methods are no longer sufficient to meet the demands for high spatial resolution, complex three-dimensional structure construction, and compatibility with multiple materials.

[0003] In recent years, photopolymerization-assisted additive manufacturing technology has made progress in the field of glass micro and nanostructure fabrication. It can achieve high-precision processing of complex three-dimensional geometric structures and obtain high-transmittance silica glass structures after subsequent heat treatment, providing a new technical path for the fabrication of rare earth-doped silica glass devices.

[0004] In existing technologies, one approach uses an organic-inorganic hybrid photosensitive resin containing silica nanoparticles. After stereolithography printing, the organic components are removed to obtain a porous silica intermediate. Rare earth ions are then introduced through solution impregnation and densified to form a luminescent glass. This method relies on pore-assisted infiltration for ion doping, resulting in complex processes and limited spatial distribution control. Another approach introduces rare earth salts in the photosensitive ink stage. Rare earth ions are adsorbed or loaded onto the surface of silica nanoparticles and then dispersed in a photocurable resin for printing. This method can achieve a certain degree of spatially selective doping, but the rare earth ions mostly exist in a physically adsorbed form, leaving room for improvement in doping stability and uniformity. Furthermore, there is a scheme that embeds pre-fabricated phosphor particles into a silicon matrix to form a fluorescent composite material. This type of method relies on the intrinsic luminescence of crystalline fluorescent particles rather than ion-level doping of rare earth ions in the silicon-oxygen network. For high-resolution processing, two-photon direct writing technology can utilize transparent photosensitive ink containing silica nanoparticles to construct submicron-level structures and convert them into silica glass through heat treatment. Current methods typically involve directly adding rare earth salts to the ink for doping, but the dispersibility and stability of rare earth salts in photosensitive systems still have room for improvement. Furthermore, current printing precursors based on photopolymerization technology mainly consist of silica nanoparticles and a large amount of organic photosensitive resin materials. To obtain pure, transparent glass, subsequent high-temperature debinding, sintering, or densification processes are required, resulting in high heat treatment temperatures (above 1000℃), making it incompatible with low-melting-point materials.

[0005] Therefore, in order to meet the requirements of micro-nano structure patterning and on-chip integration, how to achieve uniform and stable dispersion of rare earth ions in silicon dioxide precursors and final silicon dioxide structures, complete high-conformity glass conversion at lower temperatures, and achieve controllable and predictable doping concentration remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the present invention proposes a rare-earth ion-doped silica glass photosensitive precursor for micro / nano structure fabrication and its preparation method. Through coordination compatibility and low-temperature segmented conversion processes, the problems of uneven rare-earth ion dispersion, high heat treatment temperature, morphological distortion, and difficulty in quantitatively controlling the doping concentration during microstructure fabrication are solved. To achieve the above objectives, the present invention adopts the following technical solution: To achieve the above objectives, the present invention adopts the following technical solution: A photocurable rare-earth ion-doped silica glass, the raw materials for which are prepared include the following components: Polyhedral oligomeric silsesquioxanes containing acrylic acid groups, acrylate crosslinking agents, photoinitiators, and rare earth organic complexes; The mass ratio of the polyhedral oligomeric silsesquioxane containing acrylic acid groups, the acrylate crosslinking agent, and the photoinitiator is 80~95:3~15:0.5~5; The mass ratio of the rare earth organic complex to the sum of the acrylic acid-containing polyhedral oligomeric silsesquioxane, acrylate crosslinking agent, and photoinitiator is ≤1:25; The rare earth organic complex includes erbium-polyether coordination complexes.

[0007] Preferably, the rare earth organic complex further includes a ytterbium-β-diketone ligand complex; The molar ratio of erbium to ytterbium in the rare earth organic complex is 1:5~20.

[0008] Preferably, the method for preparing the rare earth organic complex includes: Polyether is dissolved in an alcohol solvent to obtain a polyether solution, and a rare earth element compound is dissolved in an alcohol solvent to obtain a rare earth element solution; the rare earth element solution and the polyether solution are mixed to carry out a coordination reaction, and the solvent is removed to obtain a rare earth organic complex.

[0009] Preferably, the rare earth element-containing compound includes an erbium source compound or a mixture of an erbium source compound and a ytterbium source compound; The erbium source compound includes one or more of erbium nitrate, erbium chloride, and erbium acetate; The ytterbium source compound includes one or more of ytterbium acetylacetonate, ytterbium acetate, and ytterbium octanoate.

[0010] Preferably, the acrylate crosslinking agent includes one or more of trimethylolpropane ethoxylated triacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate; The photoinitiator includes one or more of 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexylphenyl methyl ketone, and 2,2-dimethoxy-2-phenylacetophenone.

[0011] Another object of the present invention is to provide a method for preparing photocurable rare earth ion-doped silica glass, comprising the following steps: 1) Mix polyhedral oligomeric silsesquioxane containing acrylic acid groups, acrylate crosslinking agents, and photoinitiators to obtain a photosensitive resin matrix; 2) The rare earth organic complex was mixed with the photosensitive resin matrix and degassed to obtain a rare earth ion-doped silica precursor; 3) Selective exposure and curing of rare earth ion-doped silicon dioxide precursors are performed using ultraviolet lithography or two-photon direct writing to form predetermined two-dimensional or three-dimensional microstructures; 4) Use a developer to remove unexposed or uncured areas, and then develop the product; 5) The developed rare earth ion-doped photosensitive resin is subjected to non-sintering heat treatment to obtain photocurable rare earth ion-doped silica glass.

[0012] Preferably, the predetermined two-dimensional structure etched by ultraviolet light in step 3); Two-photon direct writing yields the predetermined three-dimensional structure.

[0013] Preferably, the developer in step 4) includes isopropanol and / or ethanol; The development time is 5 to 20 minutes.

[0014] Preferably, the non-sintering heat treatment in step 5) is a segmented gradient heating heat treatment; The segmented gradient heating heat treatment operation is as follows: heat up to 250~320℃ and hold for 0.5~3 h, then heat up to 360~430℃ and hold for 0.5~3 h, then heat up to 600~660℃ and hold for 0.5~3 h to complete the segmented gradient heating heat treatment. The heating rate is 0.2~5℃ / min.

[0015] Another objective of this invention is to provide an application of the photocurable rare-earth ion-doped silica glass prepared by the above-mentioned method in the preparation of rare-earth-doped optical waveguides, microcavities, microstructure light-emitting units, and integrated photonic devices.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: This invention introduces polyether as a coordinating and compatible molecule into a photosensitive polyhedral oligomeric silsesquioxane precursor system, enabling Er... 3+ The rare earth ions form a stable coordination structure with the ether oxygen atoms in the polyether, thereby effectively improving the solubility, dispersibility, and system stability of rare earth ions in weakly polar organic-inorganic hybrid systems. Compared with the direct incorporation of rare earth salts into photosensitive resins, this invention can significantly reduce the local enrichment and aggregation tendency of rare earth ions in the precursor, thereby reducing the risk of scattering loss, luminescence quenching, and processing defects. Simultaneously, the polyether has a certain coating and steric hindrance effect on the rare earth ions, which is beneficial for maintaining the uniform distribution of rare earth components during solution mixing, photocuring, and subsequent non-sintering heat treatment. Therefore, this invention can obtain a uniformly dispersed and processably stable rare earth-doped photosensitive precursor, and provides a foundation for the subsequent preparation of rare earth-doped silica glass microstructures with uniform composition and stable performance.

[0017] This invention employs a polyhedral oligomeric silsesquioxane monomer containing photopolymerizable functional groups as the main inorganic precursor framework, and combines it with a multifunctional acrylate crosslinking agent and a photoinitiator to construct a precursor system with good photocuring response. This system possesses both a high silicon-oxygen content and good film-forming properties, exposure responsiveness, and pattern retention, meeting the requirements of micro / nano fabrication processes such as UV lithography and two-photon direct writing for material rheology, photosensitivity, and structural stability. Through the above design, this invention achieves effective coordination between the introduction of rare-earth functional components and microstructure processing performance. This invention further achieves the conversion of the precursor into amorphous silica glass at temperatures below 700°C through a segmented gradient heat treatment process. This conversion process does not rely on traditional high-temperature sintering densification mechanisms, but rather achieves glass conversion through the gradual removal of organic components, the gradual condensation of the silicon-oxygen framework, and the in-situ reconstruction of the continuous Si-O-Si network. Compared with existing high-temperature melting or sintering processes, this invention significantly reduces the heat treatment temperature, which is beneficial for improving structural integrity and processing compatibility. This invention is particularly suitable for on-chip micro / nano structures, complex three-dimensional structures, and heat-sensitive integrated device substrates.

[0018] The precursor system constructed in this invention is compatible with both ultraviolet lithography and two-photon direct writing methods. It can be used for the rapid replication of large-area two-dimensional regular patterns, as well as for the layer-by-layer construction of high-resolution, high-degree-of-freedom three-dimensional microstructures. Compared with existing technologies that rely on porous intermediate impregnation, post-doping, or multi-step densification processes, this invention achieves an integrated process of uniform doping, patterning, and glass conversion in the precursor stage, offering advantages such as simplified process, good repeatability, and strong scalability.

[0019] Furthermore, this invention establishes a mass conservation mapping relationship between the amount of rare earth added in the precursor and the rare earth concentration in the final glass. By measuring the mass loss coefficient during the thermal conversion of the precursor, the feed concentration in the precursor can be inferred from the doping concentration in the target glass, thereby achieving predictable setting and quantitative control of the doping content. This method overcomes the shortcomings of existing technologies that rely on experience-based feeding and result in large deviations in the final doping concentration, which is beneficial for improving the consistency of material composition, the repeatability of device performance, and the stability of process scale-up applications.

[0020] In summary, this invention demonstrates excellent overall technical performance in terms of uniform rare earth ion dispersion, low-temperature non-sintering glass conversion, microstructure morphology preservation, and predictable control of doping concentration. It has promising application prospects in the fabrication of optical waveguides, microcavity resonators, on-chip gain devices, light-emitting microstructures, and other integrated photonic devices. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 For Er 3+ Schematic diagram of coordination interaction between ether oxygen atoms in PEG segments; Figure 2 The TG / DTG curve of the rare earth ion-doped silica precursor with patterned microstructure prepared in Example 1 of this invention; Figure 3 The images show SEM characterizations of the photocurable rare-earth ion-doped silica glasses prepared in Examples 1 and 3 before and after non-sintering heat treatment. Figure 3 In the image, a is a SEM image of the rare-earth ion-doped silica precursor with patterned microstructure prepared in Example 1; b is a SEM image of the rare-earth ion-doped silica precursor with patterned microstructure prepared in Example 3; c is a SEM image of the photocurable rare-earth ion-doped silica glass (without sintering heat treatment) prepared in Example 1; d is a SEM image of the photocurable rare-earth ion-doped silica glass (without sintering heat treatment) prepared in Example 3; e is a SEM image of the lettering "Northwest University" processed using the photocurable rare-earth ion-doped silica glass described in Example 3; and f is a pseudo-color fluorescence image of the lettering "Northwest University" processed using the photocurable rare-earth ion-doped silica glass described in Example 3, captured by an infrared confocal system under 980nm wavelength excitation. Detailed Implementation

[0023] This invention provides a photocurable rare-earth ion-doped silica glass, the raw materials for which are prepared contain the following components: Polyhedral oligomeric silsesquioxanes containing acrylic acid groups, acrylate crosslinking agents, photoinitiators, and rare earth organic complexes.

[0024] In this invention, a polyhedral oligomeric silsesquioxane monomer provides a silicon-oxygen backbone precursor network, a crosslinking agent adjusts the crosslinking density and mechanical strength, and a photoinitiator ensures the efficiency of the photocuring reaction.

[0025] In this invention, the mass ratio of the polyhedral oligomeric silsesquioxane containing acrylic acid groups, the acrylate crosslinking agent, and the photoinitiator is 80~95:3~15:0.5~5, preferably 85~90:5~10:1~4, and more preferably 88:8:2~3.

[0026] In this invention, the mass ratio of the rare earth organic complex to the sum of the polyhedral oligomeric silsesquioxane containing acrylic acid groups, the acrylate crosslinking agent and the photoinitiator is ≤1:25, preferably 1:25~50, more preferably 1:25~40, and even more preferably 1:25~30.

[0027] In this invention, the rare earth organic complex includes an erbium-polyether coordination complex.

[0028] In this invention, the rare earth organic complex also includes a ytterbium-β-diketone ligand complex.

[0029] In this invention, the molar ratio of erbium to ytterbium in the rare earth organic complex is 1:5 to 20, preferably 1:8 to 15, and more preferably 1:10.

[0030] In this invention, Er 3+ Instead of being added directly to the photosensitive resin as an inorganic salt, it first coordinates with the ether oxygen atoms in the polyether (such as PEG) molecular chain to form a stable complex structure. The PEG molecular chain is rich in -COC- ether oxygen structures, Er... 3+ As a high charge density ion, it readily forms coordinate bonds with ether oxygen; after coordination, it forms a "molecular encapsulation" structure, effectively reducing Er. 3 + This invention addresses the localized aggregation tendency in weakly polar photosensitive resins, improving the dispersion stability of rare earth elements in the precursor. Furthermore, it avoids the disruption of the photocurable network crosslinking density by excessive polyether (such as PEG), controls the system viscosity and photolithographic resolution, and ensures the continuity of the inorganic network after thermal conversion.

[0031] In this invention, Yb 3+ If added in the form of inorganic salts, it will react with Er 3+Competitive PEG coordination; leading to Er 3+ Reduced free and dispersed properties; this invention uses organic ligands to stabilize Yb 3+ This avoids competition for PEG coordination sites and reduces the organic content in the organic precursor, thereby improving the stability of the co-doped system. Additionally, Yb 3+ It has a strong absorption cross section near 980 nm, through energy transfer (Yb 3+ →Er 3+ ) Improve Er 3+ Increased excitation efficiency, improved 1.5 μm luminescence intensity, and reduced Er. 3+ Risk of concentration quenching when using mono-doped formulations.

[0032] In this invention, the method for preparing the rare earth organic complex includes: dissolving a polyether in an alcohol solvent to obtain a polyether solution, dissolving a rare earth element compound in an alcohol solvent to obtain a rare earth element solution; mixing the rare earth element solution with the polyether solution to carry out a coordination reaction, and removing the solvent to obtain the rare earth organic complex.

[0033] In this invention, the coordination molar ratio of erbium to the ether oxygen atom in the polyether is 1:3 to 10, preferably 1:4 to 8, and more preferably 1:5.

[0034] In this invention, the rare earth element-containing compound includes an erbium source compound or a mixture of an erbium source compound and a ytterbium source compound, that is, only an erbium source compound or both an erbium source compound and a ytterbium source compound can be added.

[0035] In this invention, the erbium source compound includes one or more of erbium nitrate, erbium chloride, and erbium acetate, and also includes the corresponding hydrates.

[0036] In this invention, the ytterbium source compound includes one or more of ytterbium acetylacetonate, ytterbium acetate, and ytterbium octanoate.

[0037] In this invention, the acrylate crosslinking agent includes one or more of trimethylolpropane ethoxylated triacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate; the photoinitiator includes one or more of 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexylphenyl ketone, and 2,2-dimethoxy-2-phenylacetophenone.

[0038] This invention also provides a method for preparing photocurable rare-earth ion-doped silica glass, comprising the following steps: 1) Mix polyhedral oligomeric silsesquioxane containing acrylic acid groups, acrylate crosslinking agents, and photoinitiators to obtain a photosensitive resin matrix; 2) The rare earth organic complex was mixed with the photosensitive resin matrix and degassed to obtain a rare earth ion-doped silica precursor; 3) Selective exposure and curing of rare earth ion-doped silicon dioxide precursors are performed using ultraviolet lithography or two-photon direct writing to form predetermined two-dimensional or three-dimensional microstructures; 4) Use a developer to remove unexposed or uncured areas, and then develop the product; 5) The developed rare earth ion-doped photosensitive resin is subjected to non-sintering heat treatment to obtain photocurable rare earth ion-doped silica glass.

[0039] In this invention, the predetermined two-dimensional structure is etched by ultraviolet light in step 3); the predetermined three-dimensional structure is obtained by two-photon direct writing.

[0040] In this invention, the ultraviolet light wavelength of the ultraviolet lithography in step 3) is preferably 300~405 nm, specifically 320 nm, 350 nm, 365 nm, 380 nm, or 400 nm.

[0041] In this invention, the exposure is performed in multiple cycles, with the preferred exposure time being 5 to 20 seconds, specifically 8 seconds, 10 seconds, 12 seconds, 15 seconds, or 18 seconds; the number of exposures can be 1 to multiple times.

[0042] In this invention, the preferred wavelength of the femtosecond laser used for two-photon direct writing is 700-900 nm, specifically 720 nm, 750 nm, 780 nm, 800 nm, 820 nm, 850 nm, or 880 nm; the preferred processing power of the femtosecond laser is 3-10 mW, specifically 4 mW, 6 mW, 5 mW, 7 mW, 8 mW, or 9 mW; and the preferred scanning speed is 20-100 μm / s, specifically 30 μm / s, 40 μm / s, 50 μm / s, 60 μm / s, 70 μm / s, 80 μm / s, or 90 μm / s.

[0043] In this invention, the developer in step 4) includes isopropanol and / or ethanol; the development time is 5 to 20 minutes, specifically 6 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes, 16 minutes, or 18 minutes, and the specific development time is based on the fact that the uncured components are fully removed and the structure is not damaged.

[0044] In this invention, the non-sintering heat treatment in step 5) is a segmented gradient heating heat treatment; the segmented gradient heating heat treatment is performed as follows: heating to 250~320℃ and holding for 0.5~3 h, then heating to 360~430℃ and holding for 0.5~3 h, then heating to 600~660℃ and holding for 0.5~3 h, thus completing the segmented gradient heating heat treatment; wherein, the first heating temperature can specifically be 260℃, 280℃, 300℃, 310℃, the second heating temperature can specifically be 380℃, 400℃, 410℃, 420℃, and the third heating temperature can specifically be 610℃, 620℃, 640℃, 650℃; the holding times for the three stages are independent and can be 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, respectively. h; the heating rate is 0.2~5℃ / min, specifically.

[0045] In this invention, the non-sintering heat treatment refers to: within a temperature range not exceeding 700°C, by segmentally removing organic components and promoting in-situ reconstruction of the Si-O-Si network, the precursor is directly transformed into a continuous amorphous SiO2 glass structure without the need for the traditional high-temperature sintering densification step.

[0046] In this invention, a segmented gradient heating heat treatment is performed under an oxidizing atmosphere. The mechanism consists of three stages: the first stage (250~320℃) removes low-molecular-weight residues and some organic segments; the second stage (360~430℃) involves the cleavage of the organic cross-linked network, leading to the gradual formation of a Si-O-Si structure; and the third stage (600~660℃) involves the rearrangement of the silicon-oxygen network, forming a continuous amorphous silicon dioxide network. This process does not rely on traditional high-temperature sintering densification but achieves glass transformation through molecular-level organic removal and in-situ inorganic network reconstruction. Its advantages include reducing the risk of structural collapse, maintaining the microstructure morphology, and suitability for integrating photonic devices.

[0047] In this invention, the mass loss coefficient k of the precursor-to-glass conversion is measured before the heat treatment. Based on the law of conservation of mass, the rare earth concentration Cp in the precursor (referring to rare earth ion-doped silica precursor) and the rare earth concentration Cg in the target glass are set to satisfy Cp=Cg(1-k), where k is 0.50~0.80, specifically 0.55, 0.60, 0.65, 0.70, and 0.75. Let k (mass loss ratio) be the mass loss coefficient of the precursor converted to glass after heat treatment. Under the condition that the volatilization loss of rare earth elements is negligible, the final rare earth concentration Cg in the glass and the rare earth concentration Cp in the precursor satisfy the mass conservation relationship Cp=Cg(1-k). Based on this, Cp can be deduced from the target Cg, achieving predictable and controllable setting of the doping concentration.

[0048] The present invention also provides an application of the photocurable rare earth ion-doped silica glass prepared by the above preparation method in the preparation of rare earth-doped optical waveguides, microcavities, microstructure light-emitting units and integrated photonic devices.

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Example 1

[0051] 1. Preparation method of photosensitive precursor

[0052] (1) Preparation of photosensitive resin matrix

[0053] Polyhedral oligomeric silsesquioxane (POSS monomer, structural formula shown in Formula 1) containing acrylic acid groups was mixed at a mass fraction of 89 wt% with trimethylolpropane ethoxylated triacrylate at a mass fraction of 9 wt%. The mixture was magnetically stirred at room temperature for 20 min. Then, 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone photoinitiator was added to the mixture at a mass fraction of 2 wt%. The mixture was magnetically stirred at room temperature for 24 h to ensure thorough mixing. Afterward, the mixture was placed in a 75°C constant temperature vacuum oven for 12 h to remove air bubbles and promote complete dissolution of the photoinitiator, resulting in a pale yellow photosensitive POSS resin, which is the photosensitive resin matrix.

[0054] (2) Preparation of PEG solution

[0055] Take 10g of polyethylene glycol, vacuum dry it, and then dissolve it in anhydrous ethanol to prepare a 20 wt% PEG / ethanol solution.

[0056] (3) Preparation of rare earth ethanol solution

[0057] Dissolve 53 mg of erbium nitrate pentahydrate and 0.56 g of ytterbium acetylacetonate in an appropriate amount of anhydrous ethanol, wherein Er 3+ With Yb 3+ The molar ratio was 1:10, resulting in a rare earth salt ethanol solution.

[0058] (4) Er 3+ -PEG coordination complexation reaction

[0059] Under continuous stirring, the rare earth ethanol solution obtained in step (3) was added dropwise to the PEG / ethanol solution obtained in step (2) at a constant rate, so that Er 3+It coordinates with the ether oxygen atom in the PEG chain segment (see schematic diagram). Figure 1 (As shown). The Er 3+ The molar ratio of PEG to ether oxygen atoms is controlled at 1:6 to ensure the formation of a stable coordination structure. In practice, PEG is added in excess to further improve Er. 3+ The dispersion stability in the system was improved and its compatibility with the POSS matrix was enhanced. The mixture was then stirred in a closed system at 60°C for 3 hours and ultrasonically treated at 30°C for 30 minutes to obtain a clear rare earth coordination solution.

[0060] (5) Obtaining rare earth organic complexes

[0061] The above solution was dried in a vacuum oven at 70°C for 24 hours to remove the ethanol solvent, yielding a rare earth organic complex, wherein Yb 3+ It exists in the form of a β-diketone complex, Er 3+ It forms a coordination structure with the PEG molecular chain.

[0062] (6) Preparation of rare earth ion-doped silica precursor

[0063] The rare earth organic complex was added to the photosensitive POSS resin prepared in step (1) at a mass ratio of 1:25; the mixture was stirred at room temperature for 3 hours to ensure uniform dispersion; and then allowed to stand for 24 hours to eliminate air bubbles in the system, thus obtaining a rare earth ion-doped silica precursor.

[0064] Formula 1:

[0065] 2. Microstructure photolithography forming method

[0066] Ultraviolet lithography forming method

[0067] (1) Cleaning the substrate

[0068] A quartz glass plate measuring 10 mm × 10 mm and 0.5 mm in thickness was selected as the substrate and ultrasonically cleaned with acetone, isopropanol, and ultrapure water for 10 minutes in sequence to remove surface impurities. The cleaned substrate was then placed in a ventilated area to air dry.

[0069] (2) Spin coating to form a film

[0070] A suitable amount of rare-earth ion-doped silica precursor was dropped onto the substrate surface and spin-coated using a spin coater. The spin coating process consisted of two stages: the first stage involved a spin coater speed of 800 rpm for 15 s, and the second stage involved a spin coater speed of 2500 rpm for 30 s. The resulting film thickness was 40 μm.

[0071] (3) Ultraviolet exposure

[0072] Patterning was performed using ultraviolet light with a wavelength of 365 nm. The mask was made of film-grade plastic. After preparing the mask, the quartz substrate was placed on the operating table of the photolithography machine and fixed with a suction cup. The mask was then attached to a glass baffle above the operating table to prevent contact with the liquid resin and contamination. Finally, exposure was performed for 10 seconds, followed by a 10-second pause, repeated once to ensure complete photocuring.

[0073] (4) Development

[0074] After exposure, the sample is immersed in isopropanol for development for 15 minutes to remove precursor material from unexposed areas.

[0075] (5) Cleaning and drying

[0076] After development, the sample was rinsed with ethanol and ultrapure water in sequence to remove residual developer; then it was naturally dried in a ventilated environment to obtain a rare earth ion-doped silica precursor with patterned microstructure.

[0077] 3. Non-sintering heat treatment

[0078] The cured structure was subjected to non-sintering heat treatment using a tube furnace with air as the heating atmosphere and a gradient heating scheme. The specific steps were as follows: the temperature was raised at a constant rate of 1℃ / min throughout the process, first from room temperature to 280℃ and held constant for 1 hour; then the temperature was raised to 395℃ at the same rate and held constant for 1 hour; then the temperature was raised to 625℃ and held constant for 1 hour; during the cooling stage, the furnace temperature was lowered from 625℃ to room temperature at a rate of 3℃ / min, thus obtaining photocurable rare earth ion-doped silica glass with an erbium doping concentration of 300ppm and a ytterbium doping concentration of 3000ppm.

[0079] Thermal analysis test

[0080] The rare-earth ion-doped silica precursor with patterned microstructures obtained in Example 1 (sample cured after development, without sintering heat treatment) was subjected to thermogravimetric analysis (TG / DTG) in air using a thermogravimetric analyzer. The heating range was from room temperature to 1000℃, and the heating rate was 5℃ / min. The TG / DTG curves showed that the precursor began to lose weight in the approximately 260–300℃ range, underwent significant weight loss in the approximately 360–420℃ range, and the weight loss leveled off above 600℃, gradually forming inorganic matter. Based on this, a segmented gradient heating heat treatment was determined to achieve the gradual removal of organic components and in-situ reconstruction of the silica network. The relevant curves are illustrated below. Figure 2 As shown.

[0081] Example 2

[0082] Based on Example 1, only Er is adjusted 3+ With Yb 3+ The designed concentrations (specific designed concentrations are shown in Table 1) were used to prepare samples 1-7 (sample 5 in Example 1). Their actual concentrations were then tested, and errors were detected. The results are shown in Table 1. Samples 1-4 are Er 3+ Single-doped systems, samples 5-7 are Er 3+ / Yb 3+ Co-doped system (Er 3+ Yb 3+ =1:10). The “design concentration” is the feed design value derived by back-calculating the mass loss coefficient k during the precursor-to-silica glass conversion process based on the rare earth ion concentration in the target glass and the mass conservation relationship. The “actual concentration” is the measured value obtained by testing the elemental content of the glass sample obtained after non-sintering heat treatment. The Er and Yb elemental contents were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and converted into corresponding ion concentrations. The “error (%)” in Table 1 is calculated according to the formula “error = |actual concentration - design concentration| / target concentration”. When the target concentration is 0, if the measured value is lower than the instrument detection limit, it is expressed as "< detection limit".

[0083] Table 1 Comparison of Design Concentration and Actual Concentration

[0084] As can be seen from Table 1, the design value of doping concentration differs from the actual value by no more than 1.5%, and the higher the doping concentration, the smaller the error control.

[0085] Example 3

[0086] The only difference between this embodiment and Embodiment 1 is that it uses two-photon direct writing for curing.

[0087] Two-photon direct writing method

[0088] (1) Light source parameters

[0089] A femtosecond laser is used as the light source, with a laser center wavelength of 780 nm, a pulse width of 140 fs, and a repetition frequency of 80 MHz.

[0090] (2) Focusing system

[0091] Focusing was performed using an objective lens with a numerical aperture (NA) of 1.25 and a magnification of 100×.

[0092] (3) Processing parameters

[0093] The laser power incident on the objective lens is 6 mW, and the scanning speed is 50 μm / s.

[0094] (4) Three-dimensional structure construction

[0095] By using a nano-positioning platform to perform layer-by-layer scanning, a three-dimensional structure can be constructed by stacking layers.

[0096] Experimental Example 1

[0097] The photocurable rare-earth ion-doped silica glasses prepared in Examples 1 and 3 were characterized by SEM before and after non-sintering heat treatment. The characterization results are as follows: Figure 3 As shown, where, Figure 3 In the image, a is a SEM image of the rare-earth ion-doped silica precursor with patterned microstructure prepared in Example 1; b is a SEM image of the rare-earth ion-doped silica precursor with patterned microstructure prepared in Example 3; c is a SEM image of the photocurable rare-earth ion-doped silica glass (without sintering heat treatment) prepared in Example 1; d is a SEM image of the photocurable rare-earth ion-doped silica glass (without sintering heat treatment) prepared in Example 3; e is a SEM image of the lettering "Northwest University" processed using the photocurable rare-earth ion-doped silica glass described in Example 3; and f is a pseudo-color fluorescence image of the lettering "Northwest University" processed using the photocurable rare-earth ion-doped silica glass described in Example 3, captured by an infrared confocal system under 980nm wavelength excitation. Figure 3 It can be seen that the precursor of the present invention can be formed into two-dimensional / three-dimensional microstructures by ultraviolet lithography or two-photon direct writing, and the microstructure maintains the overall morphology and achieves uniform shrinkage after non-sintering heat treatment; at the same time, the obtained glass microstructure exhibits near-infrared luminescence response under 980 nm excitation, indicating that rare earth ions are effectively introduced into the glass network and maintain the luminescence function.

[0098] Example 4

[0099] Based on Example 1, using the amount of polyhedral oligomeric silsesquioxane containing acrylic groups as a benchmark, only the formulation values ​​were adjusted: the mass ratio of POSS monomer containing acrylic groups, crosslinking agent, and photoinitiator was adjusted to 80:15:5; the mass ratio of rare earth organic complex to the resin matrix (POSS + crosslinking agent + initiator) was adjusted to 1:25; Er 3+ The theoretical coordination molar ratio of the polyether oxygen atom to the polyether is 1:6; the remaining preparation steps (coordination, solvent removal, mixing, degassing, UV lithography / development, and non-sintering heat treatment) are the same as in Example 1. The obtained sample was subjected to non-sintering heat treatment to obtain a rare earth ion-doped silica glass microstructure.

[0100] Example 5

[0101] Based on Example 1, using the amount of polyhedral oligomeric silsesquioxane containing acrylic groups as a benchmark, only the formulation values ​​were adjusted: the mass ratio of POSS monomer containing acrylic groups, crosslinking agent, and photoinitiator was adjusted to 88:8:2; the mass ratio of rare earth organic complex to resin matrix was 1:25; Er 3+ The theoretical coordination molar ratio of the polyether oxygen atom to the polyether is 1:6; the remaining steps are the same as in Example 1. The obtained sample is subjected to non-sintering heat treatment to obtain a rare earth ion-doped silica glass microstructure.

[0102] Example 6

[0103] Based on Example 1, using the amount of polyhedral oligomeric silsesquioxane containing acrylic groups as a benchmark, only the formulation values ​​were adjusted: the mass ratio of POSS monomer containing acrylic groups, crosslinking agent, and photoinitiator was adjusted to 95:3:2; the mass ratio of rare earth organic complex to resin matrix was 1:25; Er 3+ The theoretical coordination molar ratio of the polyether oxygen atom to the polyether is 1:6; the remaining steps are the same as in Example 1. The obtained sample is subjected to non-sintering heat treatment to obtain a rare earth ion-doped silica glass microstructure.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0105] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photocurable rare-earth ion-doped silica glass, characterized in that, Its preparation raw materials include the following components: Polyhedral oligomeric silsesquioxanes containing acrylic acid groups, acrylate crosslinking agents, photoinitiators, and rare earth organic complexes; The mass ratio of the polyhedral oligomeric silsesquioxane containing acrylic acid groups, the acrylate crosslinking agent, and the photoinitiator is 80~95:3~15:0.5~5; The mass ratio of the rare earth organic complex to the sum of the acrylic acid-containing polyhedral oligomeric silsesquioxane, acrylate crosslinking agent, and photoinitiator is ≤1:25; The rare earth organic complex includes erbium-polyether coordination complexes.

2. The photocurable rare-earth ion-doped silica glass according to claim 1, characterized in that, The rare earth organic complex also includes ytterbium-β-diketone ligand complexes; The molar ratio of erbium to ytterbium in the rare earth organic complex is 1:5~20.

3. A photocurable rare-earth ion-doped silica glass according to claim 1 or 2, characterized in that, The preparation method of the rare earth organic complex includes: Polyether is dissolved in an alcohol solvent to obtain a polyether solution, and a rare earth element compound is dissolved in an alcohol solvent to obtain a rare earth element solution; the rare earth element solution and the polyether solution are mixed to carry out a coordination reaction, and the solvent is removed to obtain a rare earth organic complex.

4. The photocurable rare-earth ion-doped silica glass according to claim 3, characterized in that, The rare earth element-containing compounds include erbium-based compounds or mixtures of erbium-based compounds and ytterbium-based compounds; The erbium source compound includes one or more of erbium nitrate, erbium chloride, and erbium acetate; The ytterbium source compound includes one or more of ytterbium acetylacetonate, ytterbium acetate, and ytterbium octanoate.

5. The photocurable rare-earth ion-doped silica glass according to claim 4, characterized in that, The acrylate crosslinking agent includes one or more of trimethylolpropane ethoxylated triacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate; The photoinitiator includes one or more of 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexylphenyl methyl ketone, and 2,2-dimethoxy-2-phenylacetophenone.

6. A method for preparing a photocurable rare-earth ion-doped silica glass according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) Mix polyhedral oligomeric silsesquioxane containing acrylic acid groups, acrylate crosslinking agents, and photoinitiators to obtain a photosensitive resin matrix; 2) The rare earth organic complex was mixed with the photosensitive resin matrix and degassed to obtain a rare earth ion-doped silica precursor; 3) Selective exposure and curing of rare earth ion-doped silicon dioxide precursors are performed using ultraviolet lithography or two-photon direct writing to form predetermined two-dimensional or three-dimensional microstructures; 4) Use a developer to remove unexposed or uncured areas, and then develop the product; 5) The developed rare earth ion-doped photosensitive resin is subjected to non-sintering heat treatment to obtain photocurable rare earth ion-doped silica glass.

7. The method for preparing photocurable rare-earth ion-doped silica glass according to claim 6, characterized in that, The predetermined two-dimensional structure etched by ultraviolet light in step 3); Two-photon direct writing yields the predetermined three-dimensional structure.

8. A method for preparing photocurable rare-earth ion-doped silica glass according to claim 6 or 7, characterized in that, The developer mentioned in step 4) includes isopropanol and / or ethanol; The development time is 5 to 20 minutes.

9. The method for preparing photocurable rare-earth ion-doped silica glass according to claim 8, characterized in that, The non-sintering heat treatment described in step 5) is a segmented gradient heating heat treatment; The segmented gradient heating heat treatment operation is as follows: heat up to 250~320℃ and hold for 0.5~3 h, then heat up to 360~430℃ and hold for 0.5~3 h, then heat up to 600~660℃ and hold for 0.5~3 h to complete the segmented gradient heating heat treatment. The heating rate is 0.2~5℃ / min.

10. The application of the photocurable rare-earth ion-doped silica glass prepared by the preparation method according to any one of claims 6 to 9 in the preparation of rare-earth doped optical waveguides, microcavities, microstructure light-emitting units and integrated photonic devices.

Images