Preparation method of high-uniformity and high-concentration Pr < 3 + > doped quartz-based glass optical fiber

Abstract

The invention relates to a preparation process of doped optical fibers, and discloses a preparation method of high-uniformity and high-concentration Pr < 3 + > doped quartz-based glass optical fibers, which comprises the following steps of: weighing rare earth oxide Pr2O3, silicon dioxide powder SiO2 and aluminum oxide Al2O3, mechanically mixing, performing ball milling, drying and sieving treatment, performing pre-sintering treatment to convert into cristobalite phase, and sintering to obtain the high-uniformity and high-concentration Pr < 3 + > doped quartz-based glass optical fibers. The method comprises the following steps: drawing a glass rod containing a fiber core by using an in-tube melting method, processing to remove an external cladding of the glass rod to obtain a fiber core rod with an adjustable diameter, combining the fiber core rod with a high-purity quartz tube by using a tube-rod method to form an optical fiber preform, and finally drawing the high-uniformity, low-loss and high-concentration Pr < 3 + >-doped silica optical fiber. Aluminum oxide Al2O3 is introduced, so that the solubility of rare earth ions Pr < 3 + > in quartz glass is improved, the melting point of a quartz raw material is reduced, and the doping concentration of rare earth is adjustable; the raw materials are converted into cristobalite phases through pre-sintering treatment, and the effects of reducing bubbles of the fiber core glass and improving the uniformity of the fiber core glass are remarkable in combination with a vacuum tube inner melting method.

Description

Technical Field

[0001] The present invention relates to a process for preparing doped optical fiber, in particular to a process for preparing rare earth ion Pr 3+ A method for preparing doped silica-based glass optical fiber. Background Art

[0002] Rare-earth-doped silica-based optical fibers serve as gain media for 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 alone in silica glass is 460 ppm. The limited solubility of rare-earth ions in silica glass makes it difficult to increase the doping concentration. Low rare-earth doping concentrations directly limit the fiber's output power, primarily manifesting as insufficient gain medium and reduced pump absorption efficiency. Furthermore, low rare-earth ion concentrations result in insufficient laser gain per unit length of the fiber, necessitating compensation by increasing the fiber length, which in turn increases transmission losses.

[0003] Core glass uniformity refers to whether the glass is structurally uniform during the manufacturing process, free of impurities, bubbles, crystal defects, or uneven density. Poor core glass uniformity can lead to defects such as increased transmission loss, reduced mechanical strength, and enhanced nonlinear effects in the resulting optical fiber.

[0004] In view of the above problems, the present invention proposes a high uniformity and high concentration Pr 3+ Preparation method of doped silica-based glass optical fiber to solve the problem of Pr 3+ The problems of low ion doping concentration, poor uniformity and high transmission loss are solved, thus achieving high uniformity, low loss and high concentration Pr 3+ Preparation of doped silica-based glass optical fibers. Summary of the Invention

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

[0006] (1) Weigh 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 Pr2O3 doping concentration is 300 ppm to 3800 ppm.

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

[0008] (3) Pre-sinter the raw material powder after ball milling, slowly raise 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 raise the temperature to 1550 ° C ~ 1650 ° C at a rate of 2 ° C / min ~ 5 ° C / min, keep the temperature for more than 2 hours to fully transform it into the quartz phase, and then cool it to room temperature with the furnace.

[0009] (4) Transfer the cristobalite block into a high-purity quartz tube with one end sealed and the other end connected to a vacuum pump with a vacuum degree 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 core and cladding of the drawn optical fiber.

[0010] (5) The quartz tube is installed on the drawing tower and melted at a high temperature of 1715℃~1800℃ (higher than the melting point of cristobalite 1713℃) using the in-tube melting method. The raw material melting time is 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 optical fiber winding speed.

[0011] (6) The drawn glass rod is ground to remove the external quartz cladding glass, and the obtained core rod is polished. The diameter of the core rod accounts for 20% to 80% of the glass rod, and the diameter of the core rod can be processed to 1 mm to 5 mm.

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

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

[0014] The present invention focuses on increasing the Pr content in quartz glass by adding aluminum oxide Al2O3 in a different proportion than the rare earth oxide Pr2O3. 3+ The solubility of Pr 3+ Doped alone 460ppm, Pr 3+The solubility in quartz glass can be increased to 3800ppm; the raw materials are ball-milled, dried, and sieved, and then pre-sintered to transform the raw materials into cristobalite blocks. After a period of vacuum melting using the tube melting method, the glass rod is drawn, and the quartz cladding outside the glass rod is removed. After polishing, a fiber core rod with good uniformity and adjustable diameter is obtained; the polished fiber core rod is combined with a high-purity quartz tube using the tube-rod method to form an optical fiber preform rod. By controlling the diameter of the fiber core rod and the outer diameter of the quartz tube, the ratio of the fiber core and the cladding is controlled. The drawn optical fiber has Pr 3+ It has the advantages of high ion doping concentration, high uniformity, low loss and adjustable fiber core diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the drawings required for describing the specific implementation or the prior art will be briefly introduced below. Obviously, the drawings described below are only one implementation of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

[0017] Figure 2 This is the XRD pattern of the raw materials after pre-calcination in the embodiment of the present invention;

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

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

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

[0021] Figure 6 This is a picture of the glass optical fiber according to an embodiment of the present invention;

[0022] Figure 7 ASE spectrum of the glass fiber under 445nm pumping for the present invention;

[0023] Figure 8 ASE spectrum of the glass fiber under 589nm pumping for the present invention;

[0024] Figure 9 This is a line scan of the XPS fiber end face diameter of the glass optical fiber implemented in the present invention;

[0025] Figure 10This is the XPS optical fiber end face element distribution diagram of the glass optical fiber implemented in the present invention;

[0026] Figure 11 Fiber absorption spectrum of the glass optical fiber used in the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the technical solutions in the specific implementation methods of the present invention are clearly and completely described below to further illustrate the present invention. Obviously, the specific implementation methods described are only part of the implementation methods of the present invention, rather than all styles.

[0028] Example 1: This example is a high uniformity and high concentration Pr 3+ Preparation method of doped silica-based glass optical fiber, such as Figure 1 As shown, the following steps are included:

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

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

[0031] (3) The sieved raw material powder was pre-calcined and slowly heated from room temperature to 200 °C to ensure that there was no organic solvent residue in the raw material after ball milling and drying. The temperature was then raised to 1650 °C at 5 °C / min and kept at this temperature for 2 h to fully transform it into the cristobalite phase. The powder was then cooled to room temperature in the furnace. The XRD pattern of the obtained cristobalite block was as follows: Figure 2 shown.

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

[0033] (5) The quartz tube is installed on the drawing tower and melted at a high temperature of 1750℃ using the in-tube melting method. The raw material melting time is 2h and the vacuum state is maintained throughout the process. Then the temperature of the drawing tower is raised to 1900℃. After the material head falls off, it is pulled to the auxiliary pulling wheel for optical fiber pulling. The glass rod is drawn by controlling the rod feeding speed and the optical fiber drawing speed. The end face of the drawn glass rod is shown as follows: Figure 3 shown.

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

[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 rod, such as Figure 4 As shown, the diameter of the core rod is 3 mm, and the outer diameter of the quartz tube is 30 mm, that is, the diameter of the core rod: the outer diameter of the quartz tube = 1:10.

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

[0037] (9) The drawn Pr 3+ Doped silica-based glass fiber was tested for ASE spectrum at 445nm and 589nm pumps, such as Figure 7 and Figure 8 shown. Figure 9 Pr 3+ XPS fiber end face diameter line scan of doped silica-based glass fiber; Figure 10 Pr 3+ XPS element distribution map of the fiber end face of doped silica-based glass fiber; Figure 11 Pr 3+ Fiber absorption spectrum of doped silica-based glass fiber.

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

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

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

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

[0042] (3) Pre-sinter the sieved raw material powder by slowly heating it 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, heat it to 1550°C at a rate of 2°C / min, keep it at that temperature for 4 hours, and then cool it to room temperature with the furnace.

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

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

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

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

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

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

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

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

[0051] (3) Pre-sinter the sieved raw material powder by slowly heating it 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, heat it to 1600°C at 4°C / min, keep it at this temperature for 4 hours, and then cool it to room temperature with the furnace.

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

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

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

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

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

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

[0058] The above describes the main technical features and basic principles of the present invention and the related advantages. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments and that the present invention can be implemented in other specific forms without departing from the concept or essential characteristics of the present invention. Therefore, from all perspectives, the above-mentioned specific embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing description, and it is intended that all changes that come within the meaning and range of equivalents of the claims be included within the present invention.

[0059] In addition, it should be understood that although this specification is described according to various implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A high uniformity and high concentration Pr 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: Weigh rare earth oxides, silica powder and alumina, ball mill the mechanically mixed raw materials, dry and sieve them, then pre-sinter the raw powder to transform it into cristobalite phase, use the tube melting method to draw a glass rod containing a fiber core, remove the outer cladding of the glass rod to obtain a fiber core rod with adjustable diameter, use the tube-rod method and combine it with a high-purity quartz tube to form an optical fiber preform, and finally perform high uniformity, low loss and high concentration Pr 3+ Drawing of doped silica optical fibers.

2. A high uniformity and high concentration Pr as claimed in claim 1 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: The molar ratio of rare earth oxide to aluminum oxide is 1:1 to 1:20, and the doping concentration of rare earth oxide is 300 ppm to 3800 ppm.

3. A high uniformity and high concentration Pr as claimed in claim 1 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: The rare earth oxide is Pr2O3.

4. A high uniformity and high concentration Pr as claimed in claim 1 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: The specific process of pre-sintering the raw material powder is to 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~1650°C at a rate of 2°C / min~5°C / min, keep it warm for more than 2 hours to fully transform it into cristobalite phase, and then cool it to room temperature with the furnace.

5. A high uniformity and high concentration Pr as claimed in claim 1 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: The process of drawing a glass rod containing a fiber core using the in-tube melting method is to transfer the cristobalite block into a high-purity quartz tube with one end closed and the other end connected to a vacuum pump with a vacuum degree of 10 2 Pa~10 5 Pa uses the tube melting method to melt at a high temperature of 1715℃~1800℃, and the raw material melting time is 1h~4h. Then the temperature of the drawing tower is raised to 1850℃~1950℃. After the material head falls, the glass rod is drawn by controlling the rod feeding speed and the optical fiber winding speed.

6. A high uniformity and high concentration Pr as claimed in claim 1 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: The process of removing the outer cladding of the glass rod is to grind the drawn glass rod to remove the outer quartz cladding glass and polish the obtained core rod. The diameter of the core rod accounts for 20% to 80% of the glass rod, and the diameter of the core rod can be processed to 1mm to 5mm.

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

25.

8. A high uniformity and high concentration Pr as claimed in claim 1 3+ A method for preparing a doped silica-based glass optical fiber, characterized in that: High concentration of Pr 3+ The drawing process of doped quartz optical fiber is as follows: the optical fiber preform is installed on the drawing tower, the drawing tower temperature is raised to 1850℃~2100℃, and after the material head falls, the Pr doping is carried out by controlling the preform feeding speed and the optical fiber drawing speed. 3+ Drawing of silica optical fiber.

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

Images