A core-clad heterogeneous fluorine-aluminum-based optical fiber and its preparation method

Abstract

The present invention discloses a core-clad heterogeneous fluorine-aluminum-based optical fiber, comprising a core and a cladding, wherein the core is made of a fluorine-aluminum-based glass material, and the cladding is made of a fluorine-phosphorus-based glass material. The raw material components of the fluorine-aluminum-based glass material are: AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2, and the raw material components of the fluorine-phosphorus-based glass material are: AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3. The present invention also discloses a method for preparing a core-clad heterogeneous fluorine-aluminum-based optical fiber. The optical fiber prepared by the present invention has a simple preparation process and can be mass-produced; it has a good core-clad interface and low optical fiber loss; it has greater environmental tolerance and longer storage time; and it has important application prospects in the field of preparation of optical fibers or optical fiber preforms.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber preparation or optical fiber preform preparation, and in particular to a core-clad heterogeneous fluorine-aluminum-based optical fiber and a preparation method thereof. Background Art

[0002] Since the tremendous development of fiber optic devices in the last century, their application has become increasingly important across various fields both domestically and internationally. They overcome the many shortcomings of space optical devices, such as enabling long-distance transmission, being less susceptible to environmental influences, and offering greater stability. Quartz fiber has long held a leading position in fiber optic devices. However, the transmission loss of quartz fiber rises sharply above 2.4 microns, significantly limiting the development of fiber optic devices in the mid-infrared band above 2.4 microns.

[0003] Fluoride and chalcogenide glasses are considered suitable materials for mid-infrared fiber devices due to their wide transmission windows and low phonon energies. While chalcogenide glass fibers have a wider transmission window than fluoride fibers, their transmittance is only around 60%, far less than the 90% of fluoride. In particular, long fiber lengths result in exponential attenuation of light within them. To date, chalcogenide fibers still suffer from high optical losses, limiting their development.

[0004] Fluoride glass materials, with their wide transmission window, high transmittance, low phonon energy, and high rare earth ion doping concentration, have broken the limitations of quartz optical fiber in mid-infrared optical devices and become an ideal material. Recent studies have shown that compared with fluorine zirconium-based and fluorine indium-based glass materials, fluorine aluminum-based glass has better chemical stability and water resistance. Therefore, it is often used as a protective end cap to prevent optical fibers from being corroded by hydroxyl groups in water molecules. It also has only slightly higher phonon energy, and has been proven to be an excellent material for realizing mid-infrared optical fiber devices. However, like other fluoride glasses, it also has a smaller glass transition temperature T x and glass crystallization temperature T g The difference (ΔT=T x -T g ) and poor thermal stability. Optical fiber preforms produced using the rod-to-tube method typically require a second heating process, which causes the glass crystallites to grow exponentially and leads to light scattering. Furthermore, the core-cladding interface of the optical fiber preform or optical fiber produced using this method is poor, which also increases fiber loss.

[0005] Therefore, technicians in this field are committed to developing a core-clad heterogeneous fluorine-aluminum-based optical fiber and a preparation method thereof to overcome the problems existing in the prior art. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to solve the loss problem of fluoride optical fibers, especially fluorine-aluminum-based optical fibers, during manufacturing and the storage problem after preparation.

[0007] To achieve the above objectives, the present invention provides a core-clad heterogeneous fluorine-aluminum-based optical fiber, comprising a core and a cladding, wherein the core is made of a fluorine-aluminum-based glass material, and the cladding is made of a fluorine-phosphorus-based glass material.

[0008] Furthermore, the raw material components of the fluorine-aluminum-based glass material are: AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2.

[0009] Furthermore, the raw material components of the fluorophosphorus-based glass material are: AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3.

[0010] Furthermore, the core and cladding are combined by an injection process to form an optical fiber preform in which the core and cladding are heterogeneous, and then drawn into an optical fiber.

[0011] The present invention also provides a method for preparing a core-clad heterogeneous fluorine-aluminum-based optical fiber, the method comprising the following steps:

[0012] Step 1: Mix the raw materials of the fluorine-phosphorus-based glass material of the cladding in a certain proportion and grind them in a mortar; mix the raw materials of the fluorine-aluminum-based glass material of the core in a certain proportion and grind them in a mortar;

[0013] Step 2: Place the fluorine-phosphorus-based glass material of the cladding and the fluorine-aluminum-based glass material of the core ground in Step 1 into a first crucible and a second crucible, respectively, and melt them in a high-temperature furnace;

[0014] Step 3: Preheat the mold with the cylindrical hole in the center;

[0015] Step 4: First, a molten fluorine-phosphorus-based glass material is poured from a first crucible into the central cylindrical hole of a preheated mold, and then a molten fluorine-aluminum-based glass material is poured from a second crucible into the same mold to form an optical fiber preform having a core-clad structure. The optical fiber preform is cooled to room temperature along with the mold.

[0016] Step 5: Polish the cooled optical fiber preform and load it onto an optical fiber drawing tower to draw the optical fiber to obtain a core-clad heterogeneous fluorine-aluminum-based optical fiber.

[0017] Furthermore, the raw material components of the fluorophosphorus-based glass material are: AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3, and the raw material components of the fluoroaluminum-based glass material are: AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2.

[0018] Furthermore, the melting in a high-temperature furnace in step 2 specifically includes: melting in a furnace at 800 to 1000° C. for more than 30 minutes.

[0019] Furthermore, the ratio of the raw material components in step 1 is adjusted according to the optical performance requirements of the fluorine-aluminum-based optical fiber.

[0020] Furthermore, the diameter of the cylindrical hole in the center of the mold in step 3 is 5 to 20 cm.

[0021] Furthermore, the preheating temperature of the mold in step 3 is determined according to the glass transition temperature and glass crystallization temperature of the fluorine-phosphorus-based glass material and the fluorine-aluminum-based glass material.

[0022] The beneficial effects of the present invention are:

[0023] (1) The optical fiber prepared by the present invention has a simple preparation process and can be mass-produced;

[0024] (2) The optical fiber prepared by the present invention has a good core-clad interface and low optical fiber loss;

[0025] (3) The optical fiber prepared by the present invention has greater environmental tolerance and longer storage time;

[0026] (4) The optical fiber prepared by the present invention has important application prospects in the field of preparation of optical fibers or optical fiber preforms.

[0027] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart for preparing a core-clad heterogeneous fluorine-aluminum-based optical fiber according to a preferred embodiment of the present invention.

[0029] Among them, 1-first crucible, 2-second crucible, 3-fluorophosphorus-based material, 4-fluoroaluminum-based material, 5-mold, 6-optical fiber preform, 7-fiber drawing area, 8-optical fiber cross section. DETAILED DESCRIPTION

[0030] The following describes preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0031] In the drawings, components with identical structures are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrary and are not limited by the present invention. For clarity, the thickness of components in some places in the drawings is appropriately exaggerated. Example

[0032] This embodiment provides a core-clad heterogeneous fluorine-aluminum-based optical fiber, the preparation of which includes the following steps:

[0033] Step 1: Mix the fluorine-aluminum-based fiber core components of AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2 in a certain proportion and grind them in a mortar.

[0034] The raw materials of the fluorophosphorus-based cladding components, AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3, were mixed in a certain proportion and ground in a mortar.

[0035] The ratio of core and cladding components can be adjusted according to the optical performance requirements.

[0036] Step 2: Place the raw materials in step 1 into crucibles and melt them in a furnace at about 900°C for ≥30 minutes.

[0037] Step 3: The fiber preform mold is preheated to a suitable temperature based on the glass transition temperature. The center of the mold has a cylindrical hole with a diameter of 5 to 20 cm.

[0038] Step 4: First, pour the molten cladding material into the hole of the preheated mold, and then pour the molten core material into the same mold. At this time, as the molten liquid shrinks, the core is sucked into the center of the cladding material, forming an optical fiber preform with a core-clad structure.

[0039] The optical fiber preform is cooled to room temperature along with the mold.

[0040] Step 5: The cooled optical fiber preform is polished and loaded onto an optical fiber drawing tower for optical fiber drawing, thereby obtaining a core-clad heterogeneous fluorine-aluminum-based optical fiber.

[0041] The core-clad heterogeneous fluorine-aluminum-based optical fiber provided in this embodiment combines the fluorine-aluminum-based core component of AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2 and the fluorine-phosphorus-based cladding component of AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3 for the first time by using the injection molding process to form an optical fiber preform with a heterogeneous core and cladding, which is then drawn into an optical fiber.

[0042] like Figure 1 As shown, S1: the ground and mixed powdered AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3 fluorophosphorus-based material 3 and the ground and mixed powdered AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2 fluoroaluminum-based material 4 are respectively loaded into the first crucible 1 and the second crucible 2, and melted in a high-temperature furnace at a melting temperature of about 900°C and a melting time of ≥30 minutes to ensure sufficient melting of the powder and formation of the glass body; S2: Subsequently, the preheated mold 5 is taken out from the low-temperature furnace, and the mold 5 has a columnar hole of 5 to 20 cm in the center. First, take out the first crucible 1 from the high-temperature furnace, and pour the liquid fluorophosphorus-based material 3 into the central cylindrical hole of the mold 5; S3: take out the second crucible 2 from the high-temperature furnace, and pour the liquid fluoroaluminum-based material 5 into the cylindrical hole of the mold 5. At this time, the fluoroaluminum-based material 4 is located above the fluorophosphorus-based material 3. As the fluorophosphorus-based material 3 shrinks, the fluoroaluminum-based material 4 is absorbed into the center of the fluorophosphorus-based material 3 to form a fluoroaluminum-based optical fiber preform 6 with a core-clad structure. Then, the mold 5 and the optical fiber preform 6 are annealed together and cooled to room temperature; S4: After the optical fiber preform 6 is taken out of the mold 5, the outer surface is polished. The area of ​​the optical fiber preform with a core-clad structure is an effective fiber drawing area 7. The optical fiber preform 6 is loaded on the drawing tower, and the fiber drawing area 7 is heated and softened. Finally, a core-clad heterogeneous fluoroaluminum-based optical fiber is obtained by controlling the rod feeding speed and the fiber drawing speed. The optical fiber cross section 8 includes a cladding made of a fluorine-phosphorus-based material 3 and a core made of a fluorine-aluminum-based material 4, as shown in FIG. Figure 1 Shown on the right side.

[0043] The beneficial effects of the present invention are:

[0044] (1) The optical fiber prepared by the present invention has a simple preparation process and can be mass-produced;

[0045] (2) The optical fiber prepared by the present invention has a good core-clad interface and low optical fiber loss;

[0046] (3) The optical fiber prepared by the present invention has greater environmental tolerance and longer storage time;

[0047] (4) The optical fiber prepared by the present invention has important application prospects in the field of preparation of optical fibers or optical fiber preforms.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a core-clad heterogeneous fluorine-aluminum-based optical fiber, characterized in that: The core-clad heterogeneous fluorine-aluminum-based optical fiber comprises a core and a cladding, wherein the core is made of a fluorine-aluminum-based glass material, and the cladding is made of a fluorine-phosphorus-based glass material. The core and the cladding are combined by an injection process to form an optical fiber preform in which the core and the cladding are heterogeneous, and the preform is drawn into an optical fiber. The method comprises the following steps: Step 1. Mix the raw materials of the fluorine-phosphorus-based glass material of the cladding in a certain proportion and grind them in a mortar; mix the raw materials of the fluorine-aluminum-based glass material of the core in a certain proportion and grind them in a mortar; the raw materials of the fluorine-aluminum-based glass material are AlF3-BaF2-CaF2-YF3-PbF2-MgF2-NH4HF2, and the raw materials of the fluorine-phosphorus-based glass material are AlF3-BaF2-CaF2-NaF-LiF-SrF2-MgF2-Al(PO3)3; Step 2: Place the fluorine-phosphorus-based glass material of the cladding and the fluorine-aluminum-based glass material of the core ground in Step 1 into a first crucible and a second crucible, respectively, and melt them in a high-temperature furnace; Step 3: Preheat the mold with the cylindrical hole in the center; The preheating temperature of the mold in step 3 is determined according to the glass transition temperature and glass crystallization temperature of the fluorine-phosphorus-based glass material and the fluorine-aluminum-based glass material; Step 4: First, pour the molten fluorine-phosphorus-based glass material from the first crucible into the central cylindrical hole of the preheated mold, and then pour the molten fluorine-aluminum-based glass material from the second crucible into the cylindrical hole of the same mold. At this time, the fluorine-aluminum-based glass material is located above the fluorine-phosphorus-based glass material. As the fluorine-phosphorus-based glass material shrinks, the fluorine-aluminum-based glass material is absorbed into the center of the fluorine-phosphorus-based glass material, forming an optical fiber preform with a core-clad structure. The optical fiber preform is cooled to room temperature along with the mold. Step 5: Polish the cooled optical fiber preform and load it onto an optical fiber drawing tower to draw the optical fiber to obtain a core-clad heterogeneous fluorine-aluminum-based optical fiber.

2. The method for preparing a core-clad heterogeneous fluorine-aluminum-based optical fiber according to claim 1, wherein: The melting in a high-temperature furnace in step 2 specifically includes melting in a furnace at 800 to 1000° C. for more than 30 minutes.

3. The method for preparing a core-clad heterogeneous fluorine-aluminum-based optical fiber according to claim 1, wherein: The diameter of the cylindrical hole in the center of the mold in step 3 is 5 to 20 cm.

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