Preparation device and preparation method of soft glass optical fiber preform

Abstract

The invention discloses a soft glass optical fiber preform preparation device and method, the preparation device comprises a base, a first driving unit, a second driving unit, a mold, a heating furnace and a control unit, one side of the base is provided with an upright guide rail, the guide rail is in sliding connection with a supporting arm, the supporting arm is connected with the output end of the first driving unit, and the second driving unit is connected with the mold. The furnace shell of the heating furnace is connected with the output end of the second driving unit, the mold is fixed in the hearth, the upper part of the mold is open, the mold is used for shaping the poured cladding glass liquid and fiber core glass liquid to obtain the soft glass optical fiber preform, and the heating furnace is used for heating and insulating the mold; the control unit is used for controlling operation of the first driving unit and the second driving unit and the temperature of the heating furnace. The preparation device and the preparation method disclosed by the invention can improve the utilization rate of the molten glass, improve the quality and concentricity of the optical fiber preform, are suitable for molds with different mold cavity diameters, and realize high-efficiency and high-quality preparation of the soft glass optical fiber preform.

Description

Technical Field

[0001] The invention belongs to the technical field of soft glass optical fiber preparation, and in particular relates to a soft glass optical fiber preform rod preparation device and a preparation method. Background Art

[0002] The 3~5 micron mid-infrared band has important application and research value in the fields of biomedicine, environmental monitoring, atmospheric remote sensing, military confrontation, etc. The most widely used quartz glass optical fiber is limited by its high phonon energy (~1100cm -1 ), which causes the transmission loss of quartz fiber to increase sharply when the wavelength is greater than ~2.3μm, and it cannot be used for the generation and transmission of 3~5μm mid-infrared lasers. Soft glass fibers represented by fluorotellurite glass fibers, fluoride glass fibers, and chalcogenide glass fibers have gradually become ideal gain media for mid-infrared fiber lasers due to their advantages such as low phonon energy and high rare earth ion doping concentration.

[0003] As the basic material for optical fiber drawing, the quality of optical fiber preform directly determines the quality of optical fiber. High-quality optical fiber preform not only has high glass purity, but also has good concentricity and low defect rate to ensure that the final optical fiber has the advantages of low loss and high transmission rate. At present, the preparation methods of soft glass optical fiber are mainly double crucible method and preform method. The double crucible method requires the glass liquid to be in a molten state for a long time during the preparation of optical fiber, so it has high requirements on the stability of glass. In addition, bubbles and crystallization are prone to exist at the interface of optical fiber core and cladding, which increases the loss of optical fiber. The preform method mainly includes drilling method, extrusion method, spiral tube method and suction injection method. The drilling method can produce optical fiber with any core-cladding ratio and any cross-sectional shape, but it cannot deal with the problem of impurity contamination at the interface of the core and cladding, so it is difficult to obtain low-loss optical fiber. The extrusion method can prepare optical fiber with any core-cladding ratio and any cross-sectional structure by designing a mold, but the commonly used ceramic mold is usually disposable, resulting in high cost, and the secondary heating during the extrusion process is easy to cause crystallization of glass. The spiral tube method reduces the impurity contamination between the core and the cladding to a certain extent, but there will be a small gap between the core and the cladding, and the residual air is difficult to remove when the optical fiber is drawn, which affects the optical performance of the optical fiber. The suction injection method is a process method with great potential at present. It mainly relies on manual operation. By pouring the molten cladding glass liquid and the core glass liquid into the mold in turn, using the thermal expansion and contraction effect, when the viscosity of the glass liquid reaches a suitable state, the mold is manually lifted, and the low-viscosity core glass liquid at the center of the mold enters the cladding glass liquid under the action of the cladding suction, thereby forming an optical fiber preform with a core-cladding interface without pollution.

[0004] However, there are still some technical difficulties in the preparation of optical fiber preforms by the traditional suction injection method. On the one hand, the cone length formed by the core glass liquid entering the cladding glass liquid is short, resulting in low material utilization; on the other hand, the cast preform is prone to defects such as bubbles, and the concentricity of the preform is difficult to accurately control. In view of these problems, the process flow and preparation equipment of the suction injection method still need to be further optimized to improve the material utilization and optical performance of the preform. Summary of the invention

[0005] In order to overcome the problems in the prior art of low utilization rate of molten glass material, poor quality and concentricity of optical fiber preform caused by fast cooling rate of molten glass, the present invention provides a soft glass optical fiber preform preparation device and preparation method which can improve the utilization rate of molten glass, enhance the quality and concentricity of optical fiber preform and are suitable for molds with different cavity diameters.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a soft glass optical fiber preform preparation device, the soft glass optical fiber preform is composed of core glass and cladding glass, the preparation device comprises a base, a first driving unit, a second driving unit, a mold, a heating furnace and a control unit, one side of the base is equipped with an upright guide rail, the guide rail is slidably connected with a support arm, the support arm is connected with the output end of the first driving unit, the first driving unit is used to drive the support arm to move up and down, the furnace shell of the heating furnace is connected with the output end of the second driving unit, the second driving unit is used to drive the heating furnace to tilt left and right, the mold is fixed in the furnace chamber, the upper part of the mold is open, the mold is used to shape the poured cladding glass liquid and the core glass liquid to obtain the soft glass optical fiber preform, the heating furnace is used to heat and keep the mold warm, and the control unit is used to control the operation of the first driving unit and the second driving unit and the temperature of the heating furnace.

[0007] The soft glass optical fiber preform preparation device of the present invention can realize the high-efficiency and high-quality preparation of soft glass optical fiber preform. In the process of preparing the soft glass optical fiber preform, the mold is heated and insulated by a heating furnace to delay the cooling of the glass liquid poured in the mold, ensuring that more core glass liquid is absorbed into the cladding glass liquid, thereby forming an optical fiber preform with a longer taper length and improving the utilization rate of the glass liquid; by synchronously tilting the heating furnace and the mold, the cladding glass liquid and the core glass liquid are poured respectively when the mold is tilted to both sides, which can effectively reduce the bubbles generated during the pouring process, obtain a higher quality optical fiber preform, and solve the problem of insufficient concentricity of the core and cladding of the optical fiber preform.

[0008] Preferably, the first driving unit includes a first motor, a screw rod and a nut, an upper mounting plate and a lower mounting plate are fixed to one side of the base, the upper mounting plate and the lower mounting plate are respectively located above and below the guide rail, the screw rod is uprightly mounted on the upper mounting plate and the lower mounting plate, the first motor is uprightly mounted on the lower side of the lower mounting plate, the first motor is controlled by the control unit, the output shaft of the first motor is connected to the screw rod, the nut is threadedly connected to the screw rod, and the nut is fixed to the support arm.

[0009] Preferably, the second driving unit comprises a second motor, the second motor is horizontally mounted on the support arm, the second motor is controlled by the control unit, and the output shaft of the second motor is connected to the furnace shell.

[0010] Preferably, a slot is provided at the entrance of the furnace of the heating furnace, and a buckle matched with the slot is fixed on the top of the mold, and the slot is used to clamp the buckle.

[0011] Preferably, the mold is formed by radially splicing a plurality of modules, the mold cavity of the mold is cylindrical, and the top of the mold cavity is connected with a conical liquid guide groove with a large upper opening and a small lower opening.

[0012] Preferably, the bottom of the mold cavity is connected to a conical liquid storage tank with a small upper opening and a large lower opening.

[0013] Preferably, a slider is fixed to one side of the support arm, and the slider is slidably connected to the guide rail.

[0014] Preferably, the base includes a pedestal and a mainboard, the mainboard is upright fixed on the pedestal, the guide rail is installed on one side of the mainboard, an upper limit switch and a lower limit switch are installed on one side of the mainboard, the upper limit switch and the lower limit switch are installed at two extreme positions of the up and down movement stroke of the support arm, and a sensing rod matching the upper limit switch and the lower limit switch is fixed on the support arm.

[0015] A method for preparing a soft glass optical fiber preform using the above-mentioned preparation device comprises the following steps: (1) adjusting the heating furnace to a horizontal position through the second driving unit, fixing the mold in the furnace, and then raising the temperature of the heating furnace to a preset temperature; (2) the heating furnace is tilted to the left to a preset angle by the second driving unit, and the molten cladding glass liquid is poured into the mold from the left side of the mold. Subsequently, the heating furnace is tilted to the right to a preset angle by the second driving unit, and the molten core glass liquid is poured into the mold from the right side of the mold. (3) The heating furnace is restored to a horizontal position by the second driving unit, and the support arm and the heating furnace are synchronously moved upward to a preset position by the first driving unit, so that the core glass liquid flows into the cladding glass liquid. After cooling, the soft glass optical fiber preform having a core-cladding structure is formed in the mold.

[0016] Preferably, in step (1), the temperature of the heating furnace is raised to 50-600°C; in step (2), the angle range of the heating furnace tilting to the left and to the right is 0-90°; in step (3), the upward movement speed of the support arm and the heating furnace is 1-30 mm / s, and the upward movement range is 1-70 cm.

[0017] Compared with the prior art, the present invention has the following advantages: the soft glass optical fiber preform preparation device and preparation method of the present invention can realize the high-efficiency and high-quality preparation of soft glass optical fiber preform. In the process of preparing the soft glass optical fiber preform, the mold is heated and insulated by a heating furnace to delay the cooling of the glass liquid poured in the mold, ensuring that more core glass liquid is absorbed into the cladding glass liquid, thereby forming an optical fiber preform with a longer taper length and improving the utilization rate of the glass liquid; by synchronously tilting the heating furnace and the mold, the cladding glass liquid and the core glass liquid are poured respectively when the mold is tilted to both sides, which can effectively reduce the bubbles generated during the pouring process, obtain a higher quality optical fiber preform, and solve the problem of insufficient concentricity of the core and cladding of the optical fiber preform. The soft glass optical fiber preform preparation device of the present invention is applicable to molds with different cavity diameters, so as to produce optical fiber preforms with different taper lengths and different thicknesses, and has the significant advantages of high efficiency and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the appearance of the soft glass optical fiber preform preparation device in Example 1 and Example 2; Figure 2 It is a schematic diagram of the state when the heating furnace in Example 1 and Example 2 is in a horizontal position; Figure 3 It is a schematic diagram of the state when the heating furnace in Example 1 and Example 2 is tilted 45° to the left; Figure 4 Schematic diagram of the state when the heating furnace in Example 1 and Example 2 is tilted 45° to the right; Figure 5 This is a perspective view of the structure of the mold in Example 1; Figure 6 It is a perspective structural diagram of the mold in Example 2; Figure 7 This is a cross-sectional picture of an optical fiber drawn from the soft glass optical fiber preform prepared in Example 3; Figure 8 is a cross-sectional picture of an optical fiber drawn from the soft glass optical fiber preform prepared in Example 4; The specific reference numerals in the figure are as follows: 11-base, 12-main board, 13-upper mounting plate, 14-lower mounting plate, 15-upper limit switch, 16-lower limit switch, 2-guide rail, 21-slider, 3-support arm, 31-sensing rod, 4-mold, 41-buckle, 42-mold cavity, 43-conical liquid guide groove, 44-conical liquid storage groove, 5-heating furnace, 51-resistance wire, 52-furnace, 53-card slot, 6-first motor, 61-screw rod, 62-nut, 7-second motor, 8-control unit. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the embodiments of the drawings. Components or structures not limited in the present invention all adopt conventional technical means in the art.

[0020] Embodiment 1: A soft glass optical fiber preform preparation device, wherein the soft glass optical fiber preform is composed of core glass and cladding glass, such as Figure 1 As shown, the preparation device includes a base, a first driving unit, a second driving unit, a mold 4, a heating furnace 5 and a control unit 8. The base includes a base 11 and a main board 12. The main board 12 is upright and fixed on the base 11. An upright guide rail 2 is installed on one side of the main board 12. The guide rail 2 is slidably connected to a slider 21. The slider 21 is fixed on one side of a support arm 3. The support arm 3 is connected to the output end of the first driving unit. The first driving unit is used to drive the support arm 3 to move up and down. The furnace shell of the heating furnace 5 is connected to the output end of the second driving unit. The second driving unit is used to drive the heating furnace 5 to tilt left and right. The mold 4 is fixed in the furnace chamber 52. The upper part of the mold 4 is open. The mold 4 is used to shape the poured cladding glass liquid and the core glass liquid to obtain a soft glass optical fiber preform. The heating furnace 5 is heated by a resistance wire 51. The heating furnace 5 is used to heat and keep the mold 4 warm. The control unit 8 is used to control the operation of the first driving unit and the second driving unit and the temperature of the heating furnace 5.

[0021] In Example 1, the first driving unit includes a first motor 6, a screw rod 61 and a nut 62. An upper mounting plate 13 and a lower mounting plate 14 are fixed to one side of a main board 12. The upper mounting plate 13 and the lower mounting plate 14 are respectively located above and below the guide rail 2. The screw rod 61 is uprightly mounted on the upper mounting plate 13 and the lower mounting plate 14. The first motor 6 is uprightly mounted on the lower side of the lower mounting plate 14. The first motor 6 is controlled by a control unit 8. The output shaft of the first motor 6 is connected to the screw rod 61. The nut 62 is threadedly connected to the screw rod 61. The nut 62 is fixed to the support arm 3; an upper limit switch 15 and a lower limit switch 16 are installed on one side of the main board 12. The upper limit switch 15 and the lower limit switch 16 are installed at two extreme positions of the up and down movement stroke of the support arm 3. A sensing rod 31 matching the upper limit switch 15 and the lower limit switch 16 is fixed to the support arm 3; the second driving unit includes a second motor 7. The second motor 7 is horizontally mounted on the support arm 3. The second motor 7 is controlled by the control unit 8. The output shaft of the second motor 7 is connected to the furnace shell.

[0022] In Example 1, a slot 53 is provided at the entrance of the furnace 52 of the heating furnace 5, and a buckle 41 adapted to the slot 53 is fixed on the top of the mold 4. The slot 53 is used to clamp the buckle 41. Specifically, Figure 5 As shown, the mold 4 is composed of several modules radially spliced ​​together. The outer diameter of the mold 4 is 50 mm, the inner diameter is 15 mm, and the total height is 150 mm. The mold cavity 42 of the mold 4 is cylindrical, and the top of the mold cavity 42 is connected with a conical liquid guide groove 43 with a large upper opening and a small lower opening, so as to better guide the glass liquid into the mold cavity 42 of the mold 4.

[0023] The soft glass optical fiber preform preparation device of Example 2 is different from that of Example 1 in that the structure of the mold 4 is different. Specifically, Figure 6 As shown, the bottom of the mold cavity 42 is connected to a tapered liquid storage tank 44 with a small upper opening and a large lower opening to accommodate more cladding glass liquid. The liquid storage tank 44 has a height of 30 mm, an upper diameter of 15 mm, and a lower diameter of 30 mm.

[0024] Embodiment 3: A method for preparing a soft glass optical fiber preform rod is implemented by using the preparation device of Embodiment 1, wherein cladding glass and core glass are prepared into an optical fiber preform rod, wherein the composition of the cladding glass is 60TeO2-20ZnO-8La2O3-12WO3, the composition of the core glass is 60TeO2-18ZnO-8La2O3-14WO3, and the refractive index of the core glass is higher than that of the cladding glass. The method for preparing an optical fiber preform rod comprises the following steps: (1) The heating furnace 5 is adjusted to a horizontal position by the second motor 7, such as Figure 2 As shown, the mold 4 is fixed in the furnace 52, and then the temperature of the heating furnace 5 is raised to 400°C, which is close to the transition temperature Tg of the glass liquid component; (2) The heating furnace 5 is tilted 45° to the left by the second motor 7, as shown in FIG. Figure 3 As shown, 50 g of molten cladding glass liquid is poured into the mold 4 from the left side of the mold 4 through the crucible 91, and then the heating furnace 5 is tilted to the right by 45° through the second motor 7, as shown in FIG. Figure 4 As shown, 30 g of molten core glass liquid is poured into the mold 4 from the right side of the mold 4 through the crucible 92; (3) The heating furnace 5 is restored to a horizontal position by the second motor 7, and the support arm 3 and the heating furnace 5 are synchronously moved up 70 cm at an upward speed of 10 mm / s by the first motor 6, so that the core glass liquid flows into the cladding glass liquid, and a soft glass optical fiber preform with a core-cladding structure is obtained in the mold 4. Then the mold 4 together with the soft glass optical fiber preform is taken out from the furnace 52 of the heating furnace 5, and put into an annealing furnace, and annealed and cooled at 380°C until the soft glass optical fiber preform is taken out after cooling to room temperature. After testing, the effective length of the soft glass optical fiber preform is about 300 mm, and the core is in a pointed cone shape in the cladding, and the minimum diameter of the tip is 1-2 mm. The soft glass optical fiber preform prepared in Example 3 is drawn into an optical fiber, Figure 7 This is a cross-sectional picture of the drawn optical fiber. The minimum core diameter of the optical fiber is about 13.9μm, the concentricity between the cladding and the core is less than 1μm, and the contact interface between the cladding and the core is excellent.

[0025] Example 4: The method for preparing a soft glass optical fiber preform rod implemented by the preparation device of Example 2 is different from that of Example 3 in that, in Example 4, the composition of the cladding glass is 70TeO2-20ZnO-10La2O3, the composition of the core glass is 75TeO2-15ZnO-10La2O3, and the amounts of the cladding glass liquid and the core glass liquid are 80g and 30g, respectively. The bottom of the mold cavity 42 of the mold 4 used is connected to a conical liquid storage tank 44 with a small upper opening and a large lower opening. The effective length of the soft glass optical fiber preform rod prepared in Example 4 is about 500mm, and the core is in a pointed cone shape in the cladding, with a minimum diameter of 1~2mm at the tip. The soft glass optical fiber preform rod prepared in Example 4 is drawn into an optical fiber, Figure 8 This is a cross-sectional picture of the drawn optical fiber. The minimum core diameter of the optical fiber is about 9.6μm, the concentricity of the cladding and the core is less than 1μm, and the contact interface between the cladding and the core is excellent.

[0026] The above embodiments are only preferred examples of the present invention and are not intended to limit the scope of the present invention. Any changes or modifications made by those skilled in the art based on the contents of the present invention should be deemed to fall within the protection scope of the present invention.

Claims

1. A device for preparing a soft glass optical fiber preform, wherein the soft glass optical fiber preform is composed of core glass and cladding glass, characterized in that: The preparation device comprises a base, a first drive unit, a second drive unit, a mold, a heating furnace and a control unit. A vertical guide rail is installed on one side of the base. The guide rail is slidably connected to a support arm. The support arm is connected to the output end of the first drive unit. The first drive unit is used to drive the support arm to move up and down. The furnace shell of the heating furnace is connected to the output end of the second drive unit. The second drive unit is used to drive the heating furnace to tilt left and right. The mold is fixed in the furnace chamber. The upper part of the mold is open. The mold is used to shape the poured cladding glass liquid and core glass liquid to obtain the soft glass optical fiber preform rod. The heating furnace is used to heat and keep the mold warm. The control unit is used to control the operation of the first drive unit and the second drive unit and the temperature of the heating furnace.

2. The soft glass optical fiber preform preparation device according to claim 1, characterized in that: The first driving unit includes a first motor, a screw rod and a nut. An upper mounting plate and a lower mounting plate are fixed to one side of the base. The upper mounting plate and the lower mounting plate are respectively located above and below the guide rail. The screw rod is uprightly mounted on the upper mounting plate and the lower mounting plate. The first motor is uprightly mounted on the lower side of the lower mounting plate. The first motor is controlled by the control unit. The output shaft of the first motor is connected to the screw rod. The nut is threadedly connected to the screw rod, and the nut is fixed to the support arm.

3. The soft glass optical fiber preform preparation device according to claim 1 or 2, characterized in that: The second driving unit comprises a second motor, the second motor is horizontally mounted on the support arm, the second motor is controlled by the control unit, and the output shaft of the second motor is connected to the furnace shell.

4. The soft glass optical fiber preform preparation device according to claim 1, characterized in that: A clamping groove is arranged at the entrance of the furnace of the heating furnace, and a buckle matched with the clamping groove is fixed on the top of the mold, and the clamping groove is used to clamp the buckle.

5. The soft glass optical fiber preform preparation device according to claim 4, characterized in that: The mold is formed by radially splicing a plurality of modules. The mold cavity of the mold is cylindrical, and the top of the mold cavity is connected with a conical liquid guide groove with a large upper opening and a small lower opening.

6. The soft glass optical fiber preform preparation device according to claim 5, characterized in that: The bottom of the mold cavity is connected with a conical liquid storage tank with a small upper opening and a large lower opening.

7. The soft glass optical fiber preform preparation device according to claim 1, characterized in that: A sliding block is fixed on one side of the support arm, and the sliding block is slidably connected to the guide rail.

8. The soft glass optical fiber preform preparation device according to claim 1, characterized in that: The base includes a pedestal and a mainboard, the mainboard is upright fixed on the pedestal, the guide rail is installed on one side of the mainboard, an upper limit switch and a lower limit switch are installed on one side of the mainboard, the upper limit switch and the lower limit switch are installed at two extreme positions of the up and down movement stroke of the support arm, and a sensing rod matching the upper limit switch and the lower limit switch is fixed on the support arm.

9. A method for preparing a soft glass optical fiber preform rod using the preparation device according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) adjusting the heating furnace to a horizontal position through the second driving unit, fixing the mold in the furnace, and then raising the temperature of the heating furnace to a preset temperature; (2) the heating furnace is tilted to the left to a preset angle by the second driving unit, and the molten cladding glass liquid is poured into the mold from the left side of the mold. Subsequently, the heating furnace is tilted to the right to a preset angle by the second driving unit, and the molten core glass liquid is poured into the mold from the right side of the mold. (3) The heating furnace is restored to a horizontal position by the second driving unit, and the support arm and the heating furnace are synchronously moved upward to a preset position by the first driving unit, so that the core glass liquid flows into the cladding glass liquid. After cooling, the soft glass optical fiber preform having a core-cladding structure is formed in the mold.

10. The method for preparing a soft glass optical fiber preform according to claim 9, characterized in that: In step (1), the temperature of the heating furnace is raised to 50-600°C; in step (2), the angle range of the heating furnace tilting to the left and to the right is 0-90°; in step (3), the upward movement speed of the support arm and the heating furnace is 1-30 mm / s, and the upward movement range is 1-70 cm.

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