A highly uniform and high concentration of Pr 3+ Preparation method of doped silica-based glass optical fiber

Abstract

The application relates to a doped optical fiber preparation process and discloses a high-uniformity and high-concentration Pr 3+ The application discloses a preparation method of a doped quartz-based glass optical fiber. Rare earth oxide Pr2O3, silica powder SiO2 and aluminum oxide Al2O3 are weighed, mechanically mixed, ball milled, dried, sieved, pre-sintered to be transformed into cristobalite, drawn into a glass rod containing a core by using a tube melting method, and processed to remove the outer cladding of the glass rod to obtain a core rod with adjustable diameter. The tube rod method is combined with a high-purity quartz tube to form an optical fiber preform rod. Finally, the optical fiber preform rod has high uniformity, low loss and high concentration of Pr 3+ The application discloses a drawing method of a doped quartz optical fiber. The aluminum oxide Al2O3 is introduced to improve the solubility of the rare earth ion Pr 3+ in the quartz glass and reduce the melting point of the quartz raw material. The rare earth doping concentration is adjustable. The raw material is transformed into cristobalite by pre-sintering, and the effect of reducing the bubbles of the core glass and improving the uniformity of the core glass is remarkable by combining the vacuum tube melting method.

Description

Technical Field

[0001] This invention relates to the fabrication process of doped optical fibers, and more particularly to rare earth ion Pr 3+ Methods for preparing doped quartz-based glass optical fibers. Background Technology

[0002] Rare-earth-doped silica-based optical fibers are used as gain media in fiber lasers and fiber amplifiers. Currently, the most commonly used rare-earth-doped fiber is rare-earth-doped silica glass fiber. The solubility of rare-earth ions in silica glass alone is 460 ppm, which limits the solubility of rare-earth ions in silica glass, making it difficult to increase the doping concentration. Low rare-earth doping concentration directly limits the output power of the fiber, mainly manifested in insufficient gain medium quantity and decreased pump absorption efficiency. Furthermore, low rare-earth ion concentration results in insufficient laser gain per unit length of fiber, requiring compensation by increasing fiber length, but this increases transmission loss.

[0003] Core glass uniformity refers to whether the glass has a uniform structure during manufacturing, free from impurities, bubbles, crystal defects, or uneven density. Poor core glass uniformity will lead to disadvantages such as increased transmission loss, reduced mechanical strength, and enhanced nonlinear effects in the fabricated optical fiber.

[0004] To address the above problems, this invention proposes a method for achieving high uniformity and high concentration of Pr. 3+ A method for preparing doped silica-based glass optical fibers, aiming to solve the problem of Pr in silica-based glass. 3+ To address the problems of low ion doping concentration, poor uniformity, and high transport loss, a solution is needed to achieve high uniformity, low loss, and high Pr concentration. 3+ Fabrication of doped quartz-based glass optical fibers. Summary of the Invention

[0005] The technical solution of this invention is as follows: a Pr with high uniformity and high concentration 3+ A method for preparing doped silica-based glass optical fibers includes the following steps:

[0006] (1) Weigh out rare earth oxide Pr2O3, silicon dioxide powder SiO2 and aluminum oxide Al2O3. The molar ratio of rare earth oxide to aluminum oxide is 1:1 to 1:20 and the doping concentration of Pr2O3 is 300ppm to 3800ppm.

[0007] (2) The mechanically mixed pharmaceutical raw materials are ball-milled, dried and sieved.

[0008] (3) Pre-calcining the ball-milled raw material powder, slowly raising the temperature from room temperature to 200°C to ensure that there is no organic solvent residue in the ball-milled and dried raw material, then raising the temperature to 1550°C to 1650°C at a rate of 2°C / min to 5°C / min, holding for more than 2 hours to fully transform it into the cristobalite phase, and then cooling it to room temperature with the furnace.

[0009] (4) Transfer the cristobalite block into a high-purity quartz tube sealed at one end, and connect the other end to a vacuum pump with a vacuum level of 10. 2 Pa~10 5 Pa controls the ratio of the inner diameter to the outer diameter of the quartz tube to control the ratio of the fiber core and cladding of the drawn optical fiber.

[0010] (5) Install the quartz tube on the drawing tower and use the tube melting method to melt it at a high temperature of 1715℃~1800℃ (higher than the melting point of cristobalite 1713℃). The raw material melting time is 1h~4h. Then, raise the temperature of the drawing tower to 1850℃~1950℃. After the material head falls off, the glass rod is drawn by controlling the rod feeding speed and the fiber filament speed.

[0011] (6) Grind the glass rod to remove the outer quartz cladding glass, and polish the resulting core rod. The core rod diameter accounts for 20% to 80% of the glass rod, and the core rod diameter can be processed to 1 mm to 5 mm.

[0012] (7) The polished fiber core rod is combined with a high-purity quartz tube to form an optical fiber preform by using the tube-rod method. The ratio of the fiber core to the cladding is controlled by controlling the diameter of the fiber core rod and the outer diameter of the quartz tube. The ratio is in the range of 1:5 to 1:25.

[0013] (8) Install the optical fiber preform on the drawing tower, raise the temperature of the drawing tower to 1850℃~2100℃, and after the preform head falls off, control the preform feeding speed and the optical fiber drawing speed to perform Pr doping. 3+ Drawing of quartz optical fiber.

[0014] The key point of this invention is to increase the Pr content in quartz glass by adding alumina (Al2O3) in different proportions than rare earth oxide (Pr2O3). 3+ The solubility of Pr is higher than that of Pr 3+ Single doping 460ppm, Pr 3+The solubility in quartz glass can be increased to up to 3800 ppm. The raw material is ball-milled, dried, and sieved, then pre-fired to transform it into cubic quartz blocks. After vacuum melting using an in-tube melting method for a period of time, a glass rod is drawn. The outer quartz cladding is removed from the glass rod, and after polishing, a uniform core rod with an adjustable diameter is obtained. The polished core rod is combined with a high-purity quartz tube using a tube-rod method to form an optical fiber preform. The ratio of core to cladding is controlled by adjusting the diameter of the core rod and the outer diameter of the quartz tube. The drawn optical fiber exhibits Pr 3+ It has advantages such as high ion doping concentration, high uniformity, low loss and adjustable core diameter. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a process flow diagram of an embodiment of the present invention;

[0017] Figure 2 The image shown is an XRD pattern of the raw materials after pre-calcination in an embodiment of the present invention.

[0018] Figure 3 This is a view of the end face of a glass rod drawn by in-tube melting according to an embodiment of the present invention;

[0019] Figure 4 This is a diagram illustrating the assembly of optical fiber preforms according to an embodiment of the present invention.

[0020] Figure 5 This is a view of the end face of a glass optical fiber drawn by the rod-tube method according to an embodiment of the present invention;

[0021] Figure 6 Images of glass optical fibers from embodiments of the present invention;

[0022] Figure 7 The ASE spectrum of the glass optical fiber under 445nm pump is shown in this invention.

[0023] Figure 8 The ASE spectrum of the glass optical fiber under 589 nm pump is shown in the present invention.

[0024] Figure 9 This is a line scan of the XPS fiber end face diameter of the glass optical fiber used in this invention.

[0025] Figure 10This is an elemental distribution diagram of the XPS fiber end face of the glass optical fiber used in this invention.

[0026] Figure 11 This is the absorption spectrum of the glass optical fiber used in this invention. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the technical solutions in the specific embodiments of this invention are described clearly and completely below to further illustrate this invention. Obviously, the specific embodiments described are only a part of the embodiments of this invention, and not all of them.

[0028] Example 1: This example is a high-uniformity and high-concentration Pr 3+ Methods for preparing doped silica-based glass optical fibers, such as Figure 1 As shown, it includes the following steps:

[0029] (1) The designed glass composition is 97.91SiO2-0.19Pr2O3-1.9Al2O3 (mol%). The raw materials used are silicon dioxide, praseodymium oxide, and aluminum oxide, with n(Pr2O3):n(Al2O3) = 1:10 and the doping concentration of Pr2O3 is 1900ppm. The raw materials are weighed according to the composition. In this case, the total amount of glass oxide is 50g.

[0030] (2) The mechanically mixed pharmaceutical raw materials are ball-milled, dried and sieved. The ball-milling time is 8 hours and the ball-milling particle size is distributed in the range of 10nm to 500nm.

[0031] (3) The sieved raw material powder was pre-calcined by slowly raising the temperature from room temperature to 200°C to ensure that there was no organic solvent residue in the raw material after ball milling and drying. Then, the temperature was raised to 1650°C at a rate of 5°C / min and held for 2 hours to allow it to fully transform into the cristobalite phase. Finally, it was cooled to room temperature in the furnace. The XRD pattern of the obtained cristobalite block is shown in the figure. Figure 2 As shown.

[0032] (4) Transfer the cristobalite block into a high-purity quartz tube sealed at one end, and connect the other end to a vacuum pump with a vacuum level of 8×10⁻⁶. 2 Pa, quartz tube outer diameter 25mm, inner diameter 20mm, wall thickness 2.5mm.

[0033] (5) Install the quartz tube on the drawing tower and use the in-tube melting method to melt it at a high temperature of 1750℃. The raw material melting time is 2 hours, and a vacuum is maintained throughout the process. Then, raise the temperature of the drawing tower to 1900℃. After the material head falls, it is pulled to the auxiliary traction wheel for optical fiber traction. The glass rod is drawn by controlling the rod feeding speed and the optical fiber drawing speed. The end face diagram of the drawn glass rod is shown in the figure. Figure 3 As shown.

[0034] (6) The glass rod is ground to remove the outer quartz cladding glass, and the resulting core rod is polished to obtain a core rod with a diameter of 3mm.

[0035] (7) Using the tube-rod method, the polished fiber core rod is combined with a high-purity quartz tube to form an optical fiber preform, such as... Figure 4 As shown, the diameter of the core rod is 3mm, and the outer diameter of the quartz tube is 30mm, that is, the ratio of the core rod diameter to the outer diameter of the quartz tube is 1:10.

[0036] (8) Install the optical fiber preform on the drawing tower, raise the temperature of the drawing tower to 2000℃, and after the preform head falls off, control the preform feeding speed and the optical fiber drawing speed to perform Pr doping. 3+ The drawing of quartz optical fibers, such as Figure 5 and Figure 6 As shown, the obtained high uniformity and high concentration of Pr 3+ The doped silica-based glass fiber has a diameter of 125 μm and a core diameter of 12.5 μm.

[0037] (9) For the drawn Pr 3+ ASE spectra were measured under 445 nm and 589 nm pumps using doped quartz-based glass optical fibers, such as... Figure 7 and Figure 8 As shown. Figure 9 For Pr 3+ Line scan of the end face diameter of XPS fiber doped with quartz-based glass fiber; Figure 10 For Pr 3+ Elemental distribution diagram of XPS fiber end face of doped quartz-based glass fiber; Figure 11 For Pr 3+ Absorption spectrum of doped silica-based glass fiber.

[0038] Figure 7 and Figure 8 Pr is 1900 ppm 3+ The amplified spontaneous emission spectrum of the doped silica-based glass fiber shows that this fiber is expected to achieve laser output in the 600nm, 615nm, 645nm, 880nm and 1057nm bands. Figure 9 The graph shows the compositional gradient of the fiber end face. As can be seen from the graph, the fiber prepared by this process is a step-index fiber. Figure 10 This is a spatial distribution diagram of the elements on the fiber end face. The core elements are uniformly distributed and do not dissolve with the cladding. Figure 11The figure shows the absorption spectrum of the optical fiber. As can be seen from the figure, the background loss of the optical fiber is 0.588dB / m (663nm), the absorption of blue light is 80dB / m (450nm), and the absorption of yellow light is 60dB / m (589nm). It has strong absorption in the blue and yellow light bands, which is suitable for matching with 450nm blue semiconductor lasers and 589nm dye lasers. The low absorption loss in the 600nm-800nm ​​band is beneficial for laser output in the red and deep red light bands.

[0039] Example 2: This example is a high-uniformity and high-concentration Pr 3+ The method for preparing doped silica-based glass optical fibers includes the following steps:

[0040] (1) The designed glass composition is 92.02SiO2-0.38Pr2O3-7.6Al2O3 (mol%). The raw materials used are silicon dioxide, praseodymium oxide, and aluminum oxide, with n(Pr2O3):n(Al2O3) = 1:20 and the doping concentration of Pr2O3 is 3800ppm. The raw materials are weighed according to the composition. In this case, the total amount of glass oxide is 50g.

[0041] (2) The mechanically mixed pharmaceutical raw materials are ball-milled, dried and sieved. The ball-milling time is 10 hours and the ball-milling particle size is distributed in the range of 10nm to 500nm.

[0042] (3) The raw material powder after sieving is pre-calcined by slowly raising the temperature from room temperature to 200°C to ensure that there is no organic solvent residue in the raw material after ball milling and drying. Then, the temperature is raised to 1550°C at 2°C / min and kept at that temperature for 4 hours. Finally, the powder is cooled to room temperature in the furnace.

[0043] (4) Transfer the cristobalite block into a high-purity quartz tube sealed at one end, and connect the other end to a vacuum pump with a vacuum level of 10. 2 Pa, quartz tube outer diameter 25mm, inner diameter 15mm, wall thickness 5mm.

[0044] (5) Install the quartz tube on the drawing tower and use the tube melting method to melt it at a high temperature of 1720℃. The raw material melting time is 4 hours. The vacuum state is maintained throughout the process. Then, the temperature of the drawing tower is raised to 1850℃. After the material head falls, it is pulled to the auxiliary traction wheel for optical fiber traction. The glass rod is drawn by controlling the rod feeding speed and the optical fiber drawing speed.

[0045] (6) The glass rod is ground to remove the outer quartz cladding glass, and the resulting core rod is polished to obtain a core rod with a diameter of 1 mm.

[0046] (7) The polished fiber core rod is combined with a high-purity quartz tube to form an optical fiber preform using the tube-rod method. The fiber core rod is 1mm thick, and the high-purity quartz tube has an outer diameter of 25mm and an inner diameter of 1mm.

[0047] (8) Install the optical fiber preform on the drawing tower, raise the temperature of the drawing tower to 2000℃, and after the preform head falls off, control the preform feeding speed and the optical fiber drawing speed to perform Pr doping. 3+ Drawing of quartz optical fiber.

[0048] Example 3: This example is a high-uniformity and high-concentration Pr 3+ The method for preparing doped silica-based glass optical fibers includes the following steps:

[0049] (1) The designed glass composition is 98.95SiO2-0.05Pr2O3-1Al2O3 (mol%). The raw materials used are silicon dioxide, praseodymium oxide, and aluminum oxide, with n(Pr2O3):n(Al2O3) = 1:20 and the doping concentration of Pr2O3 is 500ppm. The raw materials are weighed according to the composition. In this case, the total amount of glass oxide is 50g.

[0050] (2) The mechanically mixed pharmaceutical raw materials are ball-milled, dried and sieved. The ball-milling time is 8 hours and the ball-milling particle size is distributed in the range of 10nm to 500nm.

[0051] (3) The raw material powder after sieving is pre-calcined by slowly raising the temperature from room temperature to 200°C to ensure that there is no organic solvent residue in the raw material after ball milling and drying. Then, the temperature is raised to 1600°C at 4°C / min, held for 4 hours, and then cooled to room temperature with the furnace.

[0052] (4) Transfer the cristobalite block into a high-purity quartz tube sealed at one end, and connect the other end to a vacuum pump with a vacuum level of 10. 3 Pa, quartz tube outer diameter 30mm, inner diameter 20mm, wall thickness 5mm.

[0053] (5) Install the quartz tube on the drawing tower and use the tube melting method to melt it at a high temperature of 1800℃. The raw material melting time is 2 hours. The whole process is kept in a vacuum state. Then, the temperature of the drawing tower is raised to 1850℃. After the material head falls, it is pulled to the auxiliary traction wheel for optical fiber traction. The glass rod is drawn by controlling the rod feeding speed and the optical fiber drawing speed.

[0054] (6) The glass rod is ground to remove the outer quartz cladding glass, and the resulting core rod is polished to obtain a core rod with a diameter of 2mm.

[0055] (7) The polished fiber core rod is combined with a high-purity quartz tube to form an optical fiber preform using the tube-rod method. The fiber core rod is 2mm thick, and the high-purity quartz tube has an outer diameter of 30mm and an inner diameter of 2mm.

[0056] (8) Install the optical fiber preform on the drawing tower, raise the temperature of the drawing tower to 2000℃, and after the preform head falls off, control the preform feeding speed and the optical fiber drawing speed to perform Pr doping. 3+ Drawing of quartz optical fiber.

[0057] The optical fibers prepared in the above three cases have advantages such as high rare earth ion doping concentration and adjustable concentration, good uniformity, low loss, adjustable core diameter, simple process, and low production cost.

[0058] The main technical features, basic principles, and related advantages of the present invention have been described above. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the concept or basic characteristics of the invention. Therefore, the above-described embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0059] Furthermore, it should be understood that although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-uniformity and high-concentration Pr 3+ A method for preparing doped silica-based glass optical fibers, characterized in that: Rare earth oxides, silica powder, and alumina were weighed and mechanically mixed. The resulting raw materials were then ball-milled, dried, and sieved. The powder was then pre-calcined to transform it into a cristobalite phase. A glass rod containing a fiber core was drawn using an in-tube melting method. The outer cladding of the glass rod was removed to obtain a core rod with an adjustable diameter. This core rod was then combined with a high-purity quartz tube using a tube-rod method to form an optical fiber preform. Finally, high-uniformity, low-loss, and high-concentration Pr were achieved. 3+ Drawing of doped silica optical fibers; The process of drawing a glass rod containing a fiber core using the in-tube melting method involves transferring a block of cristobalite into a high-purity quartz tube sealed at one end, with the other end connected to a vacuum pump at a vacuum level of 10. 2 Pa~10 5 Pa uses an in-tube melting method to melt the raw material at a high temperature of 1715℃~1800℃ for 1h~4h. Then the temperature of the drawing tower is raised to 1850℃~1950℃. After the material head falls off, the glass rod is drawn by controlling the rod feeding speed and the fiber filament speed. The molar ratio of rare earth oxides to aluminum oxide is 1:1 to 1:20, and the doping concentration of rare earth oxides is 300ppm to 3800ppm. The rare earth oxide is Pr₂O₃; The specific process of pre-calcining the raw material powder is as follows: slowly raise the temperature from room temperature to 200°C to ensure that there is no organic solvent residue in the raw material powder, then raise the temperature to 1550°C to 1650°C at a rate of 2°C / min to 5°C / min, hold for more than 2 hours to fully transform it into the cristobalite phase, and then cool it to room temperature with the furnace.

2. A high-uniformity and high-concentration Pr as described in claim 1 3+ A method for preparing doped silica-based glass optical fibers, characterized in that: The process of removing the outer cladding of the glass rod involves grinding the drawn glass rod to remove the outer quartz cladding glass, and polishing the resulting core rod. The diameter of the core rod accounts for 20% to 80% of the glass rod, and the core rod diameter can be processed to 1 mm to 5 mm.

3. A high-uniformity and high-concentration Pr as described in claim 1 3+ A method for preparing doped silica-based glass optical fibers, characterized in that: The process of combining a core rod with a high-purity quartz tube to form an optical fiber preform involves using the tube rod method to combine a polished core rod with a high-purity quartz tube to form an optical fiber preform. The ratio of the core to the cladding is controlled within the range of 1:5 to 1:25 by controlling the diameter of the core rod and the outer diameter of the quartz tube.

4. A high-uniformity and high-concentration Pr as described in claim 1 3+ A method for preparing doped silica-based glass optical fibers, characterized in that: High concentration of Pr 3+ The process of drawing doped silica optical fiber involves installing an optical fiber preform on a drawing tower, heating the tower to 1850℃~2100℃, and after the preform head falls off, Pr doping is achieved by controlling the preform feed speed and the optical fiber drawing speed. 3+ Drawing of quartz optical fiber.

5. A high-uniformity and high-concentration Pr as described in claim 1 3+ A method for preparing doped silica-based glass optical fibers, characterized in that: The mechanically mixed pharmaceutical raw materials were ball-milled for 8 hours, and the ball milling particle size distribution was in the range of 10nm to 500nm.

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