Manufacturing method of gradient refractive index optical fiber based on photo-thermal refractive glass material
Through the drawing and ion exchange process of photothermal folding glass materials, the radial Ag+ concentration and refractive index gradient distribution of the optical fiber is achieved, solving the problems of high fiber transmission loss and low production efficiency, and achieving high-quality fiber production.
Patent Information
- Application Number
- CN202510520527.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-18
AI Technical Summary
The existing photothermal refracted glass fibers have problems with high transmission loss and long production time during the production process, especially the gradient refractive index fibers have scattering losses at the interface between the core layer and the cladding, and have low production efficiency.
Optical-grade homogeneous optical fiber preform rods are made using photothermal folded glass materials. Through drawing and ion exchange processes, silver ions are formed to be distributed along the radial gradient, so as to achieve the homology between the core layer and the cladding, reduce interface defects, and ion exchange is used to exchange molten salts such as sodium ions to form a refractive index gradient.
It significantly reduces the fiber production time, reduces transmission loss, ensures the fiber quality, and has no defects in the core layer and cladding interface, improving production efficiency.
Smart Images
Figure CN120328847A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing an optical fiber, belonging to the field of optoelectronics, and particularly to a method for manufacturing a gradient refractive index optical fiber based on a photo-thermo-refractive glass material. Background Art
[0002] Photo-thermo-refractive glass (PTRG) is a new type of photosensitive glass material. After ultraviolet irradiation and heat treatment, sodium fluoride crystals can precipitate in the glass body. The crystallization process is accompanied by a permanent negative refractive index modulation (the refractive index modulation amplitude can be as high as 1000 ppm). Utilizing the photosensitive properties of this material, ultraviolet holographic exposure is performed on the glass material, and heat treatment is carried out at a reasonable temperature, and periodic refractive index modulation can be formed on the glass substrate. Moreover, this glass material also has a series of excellent properties such as good optical uniformity, good light transmittance, and good chemical uniformity. This material can be used for the manufacture of various optical elements, and is particularly suitable for manufacturing volume phase gratings. Such volume phase gratings have excellent frequency selectivity and can be used for frequency selection and frequency stabilization of lasers. They are called the "anchor of stability" of lasers and are indispensable devices for manufacturing high-performance lasers. In addition, such devices can also achieve angle selection, spectral beam combining, pulse compression, etc., and can be used in augmented reality display devices.
[0003] The main components of the most widely used photo-thermo-refractive glass are Na2O–ZnO–Al2O3–SiO2, doped with Ag + , Ce 4+ and F - and other components. The reason for the change in refractive index is the precipitation of NaF crystals with nanoscale size after ultraviolet exposure and heat treatment.
[0004] In recent years, the application of photothermally refractive glass materials in optical fibers and optical waveguide devices has received increasing attention. Researchers have tried various methods to fabricate optical waveguide and optical fiber devices on such materials. For example, unclad optical fibers have been fabricated using photothermally refractive glass materials, and step-index optical fibers have been fabricated by jointly using the rod-in-tube method and thermoplastic rubber materials. In the first type of unclad optical fiber mentioned above, the refractive index is uniformly distributed inside the photothermally refractive glass fiber. In fact, air is used as the cladding. It is difficult to avoid the loss caused by the scattering of the optical guided wave on the fiber surface in this kind of optical fiber. The second type of photothermally refractive glass optical fiber fabricated by the sleeve method has a cladding. However, since the optical fiber fabricated by this sleeve method is a step-index optical fiber and the optical field is strong at the interface between the fiber core and the cladding, the scattering loss caused by microholes and microcracks at this interface is also large, making it difficult to effectively reduce the transmission loss of the optical fiber. In addition, the currently fabricated graded-index optical fibers also have problems such as long fabrication time, which affects the production efficiency and causes invisible waste in the production process. Summary of the Invention
[0005] In order to solve the problems existing in the background technology, the present invention provides a method for fabricating a graded-index optical fiber based on photothermally refractive glass materials.
[0006] The technical solution adopted by the present invention is as follows:
[0007] The method for fabricating a graded-index optical fiber based on photothermally refractive glass materials of the present invention includes:
[0008] The first step: Use a photothermally refractive glass substrate to fabricate an optical-grade homogeneous photothermally refractive glass material block.
[0009] The second step: After machining the optical-grade homogeneous photothermally refractive glass material block, fabricate a cylindrical homogeneous photothermally refractive glass fiber preform.
[0010] The third step: Draw the cylindrical homogeneous photothermally refractive glass fiber preform to fabricate a homogeneous photothermally refractive glass fiber.
[0011] The fourth step: Perform ion exchange on the homogeneous photothermally refractive glass fiber for no more than two hours to fabricate a photothermally refractive glass graded-index optical fiber.
[0012] In the first step described above, the photothermally refractive glass substrate is a silicate glass material containing silver ions Ag + , cerium ions Ce 4+ and fluoride ions F - . The photothermally refractive glass substrate is melted and treated at 1480 - 1500 °C and then cooled to fabricate an optical-grade homogeneous photothermally refractive glass material block.
[0013] After the second step of processing, the silver ions Ag in the photothermally refractive glass homogeneous optical fiber preform + are uniformly distributed along the radial direction of the preform; the refractive index in the photothermally refractive glass homogeneous optical fiber preform is uniformly distributed along the radial direction of the preform.
[0014] After the third step of processing, the silver ions Ag in the photothermally refractive glass homogeneous optical fiber + are uniformly distributed along the radial direction of the fiber; the refractive index in the photothermally refractive glass homogeneous optical fiber is uniformly distributed along the radial direction of the fiber.
[0015] In the fourth step described above, a molten salt containing sodium ions Na + is used for ion exchange, and potassium ions K + , lithium ions Li + or silver ions Ag + are also added to the molten salt.
[0016] In the fourth step described above, the photothermally refractive glass homogeneous optical fiber is placed in a molten salt melted at 300 - 350 °C for ion exchange and kept warm for 0.1 - 2 hours.
[0017] After the fourth step of processing, the silver ions Ag in the photothermally refractive glass graded-index optical fiber + are distributed in a gradient along the radial direction of the fiber, and the silver ions Ag on the central axis of the photothermally refractive glass graded-index optical fiber + have the highest concentration, while the silver ions Ag on the surface + have the lowest concentration; the refractive index in the photothermally refractive glass graded-index optical fiber is distributed in a gradient along the radial direction of the fiber, and the refractive index on the central axis of the photothermally refractive glass graded-index optical fiber is the highest, while the refractive index on the surface is the lowest.
[0018] The beneficial effects of the present invention are as follows:
[0019] In the method for manufacturing the photothermally refractive glass optical fiber of the present invention, ion exchange is carried out after the fiber drawing is completed, and the photothermally refractive glass homogeneous optical fiber is changed into a photothermally refractive glass graded-index optical fiber, which can significantly reduce the manufacturing time of the optical fiber and ensure the manufacturing quality at the same time. A concentration gradient of Ag + is formed in the radial direction of this optical fiber, and at the same time, a radial refractive index gradient of the optical fiber is generated. The inner layer of the optical fiber has a high Ag + concentration and a high refractive index, serving as the core; the outer layer of the optical fiber has a low Ag + concentration and a low refractive index, serving as the cladding. At the same time, the manufactured optical fiber has a core layer and a cladding made of a glass material, and the core layer and the cladding are derived from the same piece of material. Therefore, there are no defects at the interface between the core layer and the cladding, reducing the scattering of light guided waves and lowering the transmission loss of the optical fiber. Description of the Drawings
[0020] Figure 1 It is the process flow chart for manufacturing the graded-index optical fiber of the photothermorefractive glass of the present invention;
[0021] Figure 2 It is the schematic structural diagram of the homogeneous optical fiber preform of the photothermorefractive glass of the present invention;
[0022] Figure 3 It is the Ag + radial distribution diagram of the concentration in the homogeneous optical fiber preform of the photothermorefractive glass of the present invention;
[0023] Figure 4 It is the radial distribution diagram of the refractive index in the homogeneous optical fiber preform of the photothermorefractive glass of the present invention;
[0024] Figure 5 It is the schematic structural diagram of the homogeneous optical fiber of the photothermorefractive glass of the present invention;
[0025] Figure 6 It is the Ag + radial distribution diagram of the concentration in the homogeneous optical fiber of the photothermorefractive glass of the present invention;
[0026] Figure 7 It is the radial distribution diagram of the refractive index in the homogeneous optical fiber of the photothermorefractive glass of the present invention;
[0027] Figure 8 It is the Ag + radial distribution diagram of the concentration in the graded-index optical fiber of the photothermorefractive glass of the present invention;
[0028] Figure 9 It is the radial distribution diagram of the refractive index in the graded-index optical fiber of the photothermorefractive glass of the present invention. Specific Embodiments
[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0030] As Figure 1 shown, the manufacturing method of the graded-index optical fiber based on the photothermorefractive glass material of the present invention is specifically as follows:
[0031] The first step: Use the photothermorefractive glass base material to manufacture and obtain an optical-grade homogeneous photothermorefractive glass material block; the photothermorefractive glass base material contains silver ions Ag + , cerium ions Ce 4+ and fluoride ions F -The silicate glass material has the following glass material components: 68.28 wt% SiO2, 4.8 wt% Al2O3, 12.9 wt% Na2O, 6.6 wt% ZnO, 4.3 wt% NaF, 2.5 wt% KBr, 0.5 wt% Ag2O, 0.02 wt% CeO2, 0.08 wt% Sb2O3, and 0.02 wt% SnO2. An optical-grade homogeneous photothermally refractive glass material block is obtained by subjecting the photothermally refractive glass substrate to melting treatment at 1480 - 1500 °C and then cooling it.
[0032] Step 2: After machining the optical-grade homogeneous photothermally refractive glass material block, a cylindrical homogeneous preform of photothermally refractive glass optical fiber is obtained, and its surface is polished. As Figure 2 shown, the radius R of the homogeneous preform of photothermally refractive glass optical fiber is 1 - 8 mm, and the length L is 5 - 50 cm. Specifically, in implementation, the radius R of the fabricated homogeneous preform of photothermally refractive glass optical fiber is 6 mm, and the length L is 10 cm; the silver ions Ag + in the fabricated homogeneous preform of photothermally refractive glass optical fiber are evenly distributed along its radial direction. As Figure 3 shown, the Ag + concentration at each part in the homogeneous preform of photothermally refractive glass optical fiber is N0; the refractive index in the fabricated homogeneous preform of photothermally refractive glass optical fiber is evenly distributed along its radial direction. As Figure 4 shown, the refractive index at each part in the homogeneous preform of photothermally refractive glass optical fiber is n0. The Ag + concentration and refractive index are both determined by the formula of the photothermally refractive glass substrate.
[0033] Step 3: Using a fiber drawing device, a homogeneous photothermally refractive glass optical fiber is obtained by drawing the cylindrical homogeneous preform of photothermally refractive glass optical fiber. As Figure 5 shown, the radius r of the homogeneous photothermally refractive glass optical fiber is 25 - 100 microns, and the length l can reach several kilometers. Specifically, in implementation, the radius r of the homogeneous photothermally refractive glass optical fiber is 25 microns, and the length l is determined by the size of the preform of photothermally refractive glass gradient-index optical fiber and can reach several kilometers; the silver ions Ag + in the fabricated homogeneous photothermally refractive glass optical fiber are evenly distributed along its radial direction. As Figure 6 shown, the Ag + concentration at each part in the homogeneous photothermally refractive glass optical fiber is N0, and the refractive index in the fabricated homogeneous photothermally refractive glass optical fiber is evenly distributed along its radial direction. As Figure 7 shown, the refractive index at each part in the homogeneous photothermally refractive glass optical fiber is n0.
[0034] Step 4: After performing ion exchange on the photothermal refractive glass homogeneous optical fiber for no more than two hours, a photothermal refractive glass graded-index optical fiber is fabricated; ion exchange is carried out using a molten salt containing sodium ions Na + , and potassium ions K + , lithium ions Li + , or silver ions Ag + are also added to the molten salt. In specific implementation, the molten salt is a mixed molten salt of NaNO3 and KNO3, where the weight ratio of NaNO3 to KNO3 is 3:1 to 10:1. In specific implementation, the weight ratio is 8:1. The photothermal refractive glass homogeneous optical fiber is placed in the molten salt melted at 300 - 350 °C for ion exchange and kept warm for 0.1 - 2 hours. In specific implementation, it is kept warm for 1 hour; the concentration of silver ions Ag + in the fabricated photothermal refractive glass graded-index optical fiber shows a gradient distribution along its radial direction. The concentration of silver ions Ag + on the central axis of the photothermal refractive glass graded-index optical fiber is the highest, and the concentration of silver ions Ag + on the surface is the lowest. As shown in Figure 8 , the concentration of Ag + on the central axis of the photothermal refractive glass graded-index optical fiber is N0, and the concentration of Ag + on the surface is N1 (N0 > N1); the refractive index in the photothermal refractive glass graded-index optical fiber shows a gradient distribution along its radial direction. The refractive index on the central axis of the photothermal refractive glass graded-index optical fiber is the highest, and the refractive index on the surface is the lowest. As shown in Figure 9 , the refractive index on the central axis of the photothermal refractive glass graded-index optical fiber is n0, and the refractive index on the surface is n1 (n0 > n1).
[0035] The above specific implementation manners are used to explain and illustrate the present invention, rather than limiting the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.
Claims
1. A method for fabricating a gradient refractive index optical fiber based on photothermally refractive glass material, characterized in that, Including: The first step: fabricating an optical-grade homogeneous photothermally refractive glass material block using a photothermally refractive glass substrate; The second step: fabricating a cylindrical homogeneous preform of photothermally refractive glass optical fiber by machining the optical-grade homogeneous photothermally refractive glass material block; The third step: fabricating a homogeneous photothermally refractive glass optical fiber by drawing the cylindrical homogeneous preform of photothermally refractive glass optical fiber; The fourth step: fabricating a photothermally refractive glass graded-index optical fiber by performing ion exchange on the homogeneous photothermally refractive glass optical fiber for no more than two hours.
2. The manufacturing method of the gradient refractive index optical fiber based on the photothermal refractive glass material according to claim 1, wherein: In the first step described above, the photothermally refractive glass substrate is a silicate glass material containing silver ions Ag + , cerium ions Ce 4+ and fluoride ions F - . After melting and cooling the photothermally refractive glass substrate at 1480-1500 °C, an optical-grade homogeneous photothermally refractive glass material block is produced and obtained.
3. The manufacturing method of the gradient refractive index optical fiber based on the photothermal refractive glass material according to claim 1, characterized in that: After the second step of processing described above, the silver ions Ag in the photothermally refractive glass homogeneous fiber preform + are uniformly distributed along the radial direction of the preform itself; the refractive index in the photothermally refractive glass homogeneous fiber preform is uniformly distributed along the radial direction of the preform itself.
4. The manufacturing method of the gradient refractive index optical fiber based on the photothermal refractive glass material according to claim 1, characterized in that: After the third step of processing described above, silver ions Ag in the photothermally refractive glass homogeneous optical fiber + are uniformly distributed along the radial direction of the fiber; the refractive index in the photothermally refractive glass homogeneous optical fiber is uniformly distributed along the radial direction of the fiber.
5. The manufacturing method of the gradient refractive index optical fiber based on the photothermal refractive glass material according to claim 1, characterized in that: In the fourth step described above, a molten salt containing sodium ions Na + is used for ion exchange, and potassium ions K + , lithium ions Li + or silver ions Ag + are also added to the molten salt.
6. The manufacturing method of the gradient refractive index optical fiber based on the photothermal refractive glass material according to claim 1, characterized in that: In the fourth step described above, the homogeneous photothermally refractive glass optical fiber is placed in a molten salt melted at 300 - 350 °C for ion exchange and heat preservation for 0.1 - 2 hours.
7. The manufacturing method of the gradient refractive index optical fiber based on the photothermal refractive glass material according to claim 1, characterized in that: After the fourth step of processing described above, silver ions Ag in the photothermal refractive glass graded-index optical fiber + have a gradient distribution along the radial direction of the fiber itself. The concentration of silver ions Ag on the central axis of the photothermal refractive glass graded-index optical fiber + is the highest, and the concentration of silver ions Ag on the surface + is the lowest; the refractive index in the photothermal refractive glass graded-index optical fiber has a gradient distribution along the radial direction of the fiber itself. The refractive index on the central axis of the photothermal refractive glass graded-index optical fiber is the highest, and the refractive index on the surface is the lowest.