WO2018211880A1 - 光ファイバ母材の製造方法および光ファイバ母材 - Google Patents
光ファイバ母材の製造方法および光ファイバ母材 Download PDFInfo
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- WO2018211880A1 WO2018211880A1 PCT/JP2018/015562 JP2018015562W WO2018211880A1 WO 2018211880 A1 WO2018211880 A1 WO 2018211880A1 JP 2018015562 W JP2018015562 W JP 2018015562W WO 2018211880 A1 WO2018211880 A1 WO 2018211880A1
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
- C03B37/01453—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering for doping the preform with flourine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
- C03B37/01228—Removal of preform material
- C03B37/01231—Removal of preform material to form a longitudinal hole, e.g. by drilling
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01466—Means for changing or stabilising the diameter or form of tubes or rods
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01466—Means for changing or stabilising the diameter or form of tubes or rods
- C03B37/01473—Collapsing
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/07—Impurity concentration specified
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
- C03B2201/50—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with alkali metals
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2205/00—Fibre drawing or extruding details
- C03B2205/08—Sub-atmospheric pressure applied, e.g. vacuum
- C03B2205/09—Sub-atmospheric pressure applied, e.g. vacuum to the outside of the preform or fibre
Definitions
- the present invention relates to a method for manufacturing an optical fiber preform to which an alkali metal is added, and an optical fiber preform manufactured by the manufacturing method.
- porous glass obtained by depositing (sooting) glass fine particles generated by subjecting glass raw materials to flame hydrolysis reaction on rotating starting materials, etc.
- a method of sintering (transparent vitrification) of a material is performed.
- This sintering process is generally performed in a He atmosphere.
- transparent glass can be easily obtained when sintered in a gas atmosphere having high solubility in glass.
- residual bubbles are generated in the obtained transparent glass in an Ar or N 2 atmosphere, but it has been found that a transparent glass free of residual bubbles is easily obtained in a highly soluble He atmosphere. For this reason, the porous base material is generally sintered in a He atmosphere.
- the optical fiber preform including the glass portion sintered as described above is spun into a thin optical fiber having an outer diameter of 100 to 200 ⁇ m in the drawing process.
- a phenomenon hereinafter referred to as “spike” in which the outer diameter (glass diameter) fluctuates by 1 ⁇ m or more suddenly may occur in the drawn optical fiber.
- This is known to be caused by bubbles mainly composed of He generated in the optical fiber preform (99% or more).
- Patent Documents 1 to 3 describe methods for reducing the residual He concentration in the transparent glass after sintering.
- the present invention has been made to solve the above-described problems, and an optical fiber mother including an alkali metal having a structure for effectively suppressing sudden spike generation during drawing of a base material. It aims at providing the manufacturing method of a material, and the optical fiber preform
- the cause of occurrence of spikes (a phenomenon in which fluctuations in the outer diameter of 1 ⁇ m or more occur suddenly in the optical fiber obtained by drawing the preform)
- the transparent glass rod having a predetermined outer diameter after sintering and before addition of alkali metal is recorded with the actual data in which the relationship between the annealing time and the residual He concentration is recorded in advance for each outer diameter.
- the annealing is performed in an atmosphere containing no He gas for the annealing time determined by reference.
- the actual data includes the actual measurement data of the residual He concentration of the manufactured optical fiber preform and the annealing time as an annealing process result of the transparent glass rod.
- an optical fiber preform that can effectively suppress the occurrence of sudden spikes during drawing of the preform is obtained.
- One aspect of the present embodiment relates to a method of manufacturing an optical fiber preform composed of a core preform and a cladding portion provided on the outer periphery of the core preform.
- the core base material includes one or more glass regions each having silica glass as a main component, and includes a central rod in which an alkali metal addition region is formed along the longitudinal direction.
- the clad portion is also composed of one or a plurality of glass regions each having silica glass as a main component.
- the manufacturing method includes at least a core base material manufacturing process, a cladding part manufacturing process, and a measurement process.
- the core base material manufacturing process includes at least a rod manufacturing process, an adding process, and a diameter expanding process.
- a clad portion composed of one or a plurality of glass regions is formed on the outer periphery of the core base material obtained through the core base material manufacturing step.
- the residual He concentration in the region corresponding to the above-described center rod is measured in the sample preform cut out from the optical fiber preform obtained through the cladding part manufacturing process.
- the core base material manufacturing process includes an annealing time determination process performed between the rod manufacturing process and the adding process, and a first annealing process.
- the annealing time determination step referring to the actual data including the He concentration-time table showing the relationship between the annealing time and the residual He concentration depending on the specific outer diameter of the transparent glass rod, the annealing process for the transparent glass rod is performed. Time is determined.
- the transparent glass rod is annealed in an atmosphere that does not contain He gas, such as at least the determined annealing time, N 2 (nitrogen) gas, Ar (argon) gas.
- the measurement data is updated in addition to the measurement of the residual He concentration in the central region (region corresponding to the central rod) in the sample base material.
- the annealing time determined by the annealing time determination process and the measured residual He concentration are added as the processing results for each outer diameter of the transparent glass rod subjected to annealing in the first annealing process. As a result, the performance data is updated.
- the manufacturing method includes an optical fiber preform obtained through the cladding part manufacturing process between the cladding part manufacturing process and the measurement process in an atmosphere not containing He gas. You may further provide the 2nd annealing process process annealed only for predetermined time.
- the annealing time in the second annealing treatment step may be fixed.
- the annealing time in the first annealing process is preferably longer than the annealing time in the second annealing process.
- the optical fiber preform according to the present embodiment is obtained by the method for manufacturing an optical fiber preform according to the various aspects described above. Specifically, as one aspect thereof, in the optical fiber preform, it is preferable that the maximum value of the residual He concentration in the center rod is adjusted to 0.15 [weight ppm] or less.
- an optical fiber preform containing an alkali metal in glass easily undergoes glass crystallization (crystallization of a glass region containing an alkali metal) by heating. In particular, if there are minute crystal nuclei, bubbles are likely to be generated starting from them.
- the spike can be sufficiently suppressed by adjusting the amount of change with respect to the initial He concentration (residual He concentration at the time of glass clarification by sintering).
- the initial He concentration residual He concentration at the time of glass clarification by sintering.
- the absolute amount of the residual He concentration in the central portion of the base material to which the alkali metal is to be added is adjusted in advance to an appropriate range before the addition of the alkali metal. Stable preform drawing is possible.
- the maximum value of the Cl concentration in the central rod is adjusted to 1000 ppm or less.
- the Cl concentration is high, crystallization of the glass region containing the alkali metal is promoted, and spikes are easily generated during drawing of the base material.
- the Cl concentration is low and the residual He concentration is not more than a predetermined value. Crystallization of a glass region containing an alkali metal becomes particularly remarkable when the annealing time is increased. Therefore, according to the present embodiment, by adjusting the Cl concentration together with the residual He concentration, crystallization of the central portion of the base material containing the alkali metal is effectively suppressed.
- each aspect listed in this [Description of Embodiments of the Invention] is applicable to each of all the remaining aspects or to all combinations of these remaining aspects. .
- An optical fiber preform manufactured by the method for manufacturing an optical fiber preform according to the present embodiment is manufactured according to the flowchart shown in FIG. 1, and includes a core preform and a cladding portion provided on the outer periphery of the core preform. Composed.
- the core base material is composed of one or a plurality of glass regions each having silica glass as a main component, and includes a center rod in which an alkali metal addition region is formed along the longitudinal direction.
- the clad portion is also composed of one or a plurality of glass regions each having silica glass as a main component.
- the core preform is a portion corresponding to the core of the optical fiber obtained by drawing the optical fiber preform, and the clad portion corresponds to the clad of the optical fiber (having a lower refractive index than the core). It is a part to do.
- FIG. 1 is a flowchart for explaining a method of manufacturing an optical fiber preform according to this embodiment.
- the optical fiber preform manufacturing method includes at least a core preform manufacturing process, a cladding part manufacturing process, and a measurement process.
- the core base material manufacturing process includes at least a rod manufacturing process, an adding process, and a diameter expanding process.
- a porous rod sin body in which glass fine particles are deposited along the longitudinal direction is manufactured (step ST10: sooting process).
- a porous rod is manufactured by the VAD (Vapor-phase Axial Deposition) method or the OVD (Outside Vapor Deposition) method.
- VAD Veryr-phase Axial Deposition
- OVD Outside Vapor Deposition
- step ST20 dehydration / sintering step
- the manufactured transparent glass rod with the outer diameter R is once installed in the heating apparatus shown in FIG. 4, and before the addition step, an annealing time determination step (step ST30) and a first annealing treatment step (step ST40). Is performed on the transparent glass rod.
- the annealing time determination process in step ST30 is a process for adjusting the concentration of He remaining in the transparent glass rod in the above-described manufacturing process, and occurs suddenly when drawing the optical fiber preform finally obtained. This is performed in order to suppress the generation of bubbles due to the He gas that causes a spike (an outside diameter fluctuation of 1 ⁇ m or more suddenly occurring in the drawn optical fiber).
- the time of annealing treatment for the transparent glass rod is determined using the actual data 700 stored for each outer diameter of the transparent glass rod and storing the relationship between the annealing time and the residual He concentration.
- the actual data 700 includes a He concentration-time table (theoretical value) indicating the relationship between the annealing time depending on the center rod having a specific outer diameter and the residual He concentration. Further, the relationship (theoretical value) between the annealing time and the residual He concentration depending on other outer diameters can be calculated from known table data (theoretical value).
- the transparent glass rod is annealed in an atmosphere not containing He gas, for example, in an N 2 gas atmosphere for the determined annealing time (step ST40).
- the concentrations of He and Cl remaining in the transparent glass rod are reduced.
- the first annealing process may be performed in an atmosphere such as Ar gas.
- an adding step is applied to the annealed transparent glass rod.
- the adding step after the annealed transparent glass rod is stretched, a hole extending along the longitudinal direction is formed in the central region of the transparent glass rod (step ST50).
- an alkali metal such as K (potassium) is added to the inner peripheral surface of the hole formed in the transparent glass rod by a CVD (Chemical Vapor Deposition) method (step).
- a core base material is obtained by the rod in collapse method (step ST70).
- the transparent glass rod after step ST60 is collapsed to obtain a center rod (step ST71).
- a peripheral core portion is provided on the outer periphery of the central rod by the rod incolapse method (step ST72).
- the rod-in collaps method includes a step of extending the integrated glass body until a desired outer diameter is obtained after integrating the glass rod and the glass tube into which the glass rod is inserted.
- the peripheral core part provided in the outer periphery of a center rod may be comprised by multiple layers, and the rod incollapse method of step ST70 is performed in multiple times (step ST80: diameter expansion process), and a desired outer diameter is obtained.
- a core base material is obtained (step ST73).
- the core base material manufacturing process includes steps ST10 to ST80, and the clad portion in which F (fluorine) is added to the outer periphery of the core base material obtained by the core base material manufacturing process.
- Is formed step ST90: cladding part manufacturing process.
- the clad part manufacturing process of step 90 manufactures a porous rod by depositing glass fine particles while adding F to the outer periphery of the core base material by the OVD method. Thereafter, dehydration and sintering are performed in the heating apparatus shown in FIG. 3, and the obtained sintered body is subjected to stretching treatment in order to obtain an optical fiber preform having a desired outer diameter.
- the clad part manufactured in the clad part manufacturing process in step ST90 may be composed of a plurality of layers having different refractive indexes.
- a second annealing process is performed to adjust the residual He concentration in the cladding part (step ST100), and an optical fiber preform is obtained.
- the second annealing process may be performed under certain conditions (for example, annealing time: 5 hours, annealing temperature: 1050 ° C.) regardless of the outer diameter of the base material.
- the lower limit value of the annealing temperature is preferably set in the range of 900 ° C. to 1000 ° C.
- the upper limit value of the annealing temperature is preferably set in the range of 1000 ° C. to 1100 ° C.
- the annealing time in the first annealing process is set longer than the annealing time in the second annealing process.
- the core base material manufacturing process including steps ST10 to ST80, including the annealing time determining process (step ST30) and the first annealing process (step ST40), and the cladding part manufacturing process of step ST90
- concentration and the update of performance data are performed with respect to the optical fiber preform
- Residual He is quantified by a high-frequency heating type temperature programmed desorption method.
- the weight of the sample in the region to be quantified is used, so unnecessary regions other than the alkali metal addition region (center rod) are removed from the sample base material by pretreatment such as cleaving and polishing. By doing so, the residual He of the center rod can be quantified.
- the maximum value of He concentration is 0.15 [weight ppm] or less for suppressing spikes, and further for suppressing glass crystallization. More preferably, the Cl concentration is 1000 ppm or less.
- the update target of the actual data that is, the annealing target in the first annealing treatment step (step ST40)
- the result data is updated.
- FIG. 2 is a diagram for explaining the above-described sooting process (the cladding part manufacturing process of step ST10 and step ST90 in the core base material manufacturing process).
- the sooting process includes at least a type A VAD (Vapor-phase Axial Deposition) method and a type B OVD (Outside Vapor Deposition) method.
- VAD Vapor-phase Axial Deposition
- OVD Outside Vapor Deposition
- the porous body 220 is formed by a predetermined sooting device.
- This sooting device includes a container having at least an exhaust port and a support mechanism for supporting the porous body 220. That is, the support mechanism is provided with a support bar that can rotate in the direction indicated by the arrow S1, and a starting bar 210 for growing the porous body 220 (soot body) is attached to the tip of the support bar. It has been.
- a burner 230 for depositing the porous body 220 is provided, and a desired material gas (for example, GeCl 4 , SiCl 4 and the like), combustion gases (H 2 and O 2 ), and carrier gases such as Ar and He are supplied.
- the material gas may contain an additive for adjusting the refractive index.
- the support mechanism performs an operation of pulling up the starting bar 210 along the direction indicated by the arrow S2 while rotating the starting bar 210 in the direction indicated by the arrow S1.
- the porous body 220 grows on the lower surface of the starting rod 210 toward the lower side of the starting rod 210, and finally the porous rod 310 (FIG. 3) to be the central rod is obtained. It is done.
- this sooting apparatus also includes a container having at least an exhaust port, and a support mechanism for supporting the mandrel 240 and the porous body deposited on the outer periphery thereof.
- the support mechanism is capable of rotating the mandrel 240 in the direction indicated by the arrow S2 while allowing the mandrel 240 to rotate in the direction indicated by the arrow S1, while depositing a porous body on the outer periphery of the mandrel 240.
- a porous body is obtained on the outer periphery of the mandrel 240.
- the core base material 110 manufactured by the core base material manufacturing process is used as the mandrel 240.
- the apparatus for performing the sooting step by the OVD method is provided with a burner 230 for depositing a porous body on the outer periphery of the mandrel 240, and the refractive index adjustment is performed on the burner 230 from the gas supply system.
- a desired material gas for example, GeCl 4 , SiCl 4, etc.
- a combustion gas H 2 and O 2
- a carrier gas such as Ar or He are supplied.
- FIG. 3 is a view for explaining the dehydration / sintering process in the core base material manufacturing process (step ST20) and the clad manufacturing process (step ST90).
- the apparatus of FIG. 3 performs dehydration and sintering (transparent vitrification) with the porous rod 310 obtained by the sooting apparatus shown in FIG. 2 installed therein.
- the apparatus of FIG. 3 includes a heating container 350 provided with a heater 300.
- the heating container 350 is provided with a gas introduction port 350A and a gas exhaust port 350B.
- a support mechanism is provided on the upper portion of the heating container 350, and the support mechanism rotates the porous rod 310 in the direction indicated by the arrow S3 while supporting the porous rod 310, and By moving the porous rod 310 in the direction indicated by the arrow S4, the relative position of the porous rod 310 with respect to the heater 300 is changed.
- step ST20 In the dehydration process of step ST20, first, the support mechanism moves the porous rod 310 in the direction indicated by the arrow S3 while rotating the porous rod 310 in the direction indicated by the arrow S4, so that the porous rod 310 is heated. Heated by 300. Meanwhile, He gas and Cl gas are introduced into the heating container 350 from the gas inlet 350A, and these introduced gases are discharged from the gas outlet 350B. Through this step, OH groups in the porous rod 310 are removed.
- the support mechanism moves the porous rod 310 after the dehydration process in the direction indicated by the arrow S4 while rotating the porous rod 310 in the direction indicated by the arrow S3.
- the quality rod 310 is heated by the heater 300.
- the heating temperature of the porous rod 310 is about 1500 ° C.
- only He gas is introduced into the heating container 350 from the gas inlet 350A, and the introduced He gas is discharged from the gas outlet 350B. Through this step, a transparent glass rod 320A is obtained.
- the transparent glass rod 320A having the outer diameter R obtained through the sintering process as described above is annealed by the annealing apparatus shown in FIG. 4 before the alkali metal is added (step ST40: first annealing). processing).
- the annealing apparatus in FIG. 4 has a heating container 400 provided with a heater 410.
- the heating container 400 has a gas introduction port 400A for supplying only N 2 gas (atmosphere not containing He gas) and an exhaust port 400B for exhausting the N 2 gas.
- a thermometer 420 is installed in the heating container 400, and the temperature control unit 430 controls the heating temperature of the heater 410 so that the temperature in the heating container 400 (set to 1050 ° C.) is managed. .
- the first annealing process by the temperature control unit 430 is performed for the annealing time determined with reference to the performance data 700 in step ST30.
- FIG. 5 shows an addition process in which an alkali metal is added to the transparent glass rod 500 in which the holes 510 are thus formed by a CVD method.
- potassium (K) is added as an alkali metal to the inner surface of the hole 510 provided in the transparent glass rod 500.
- Potassium bromide (KBr) is used as a raw material (KBr vapor is generated by heating KBr with an external heat source).
- the transparent glass rod 500 is heated from the outside by a burner (oxyhydrogen burner) 520 while introducing KBr vapor into the hole 510 of the transparent glass rod 500 using oxygen as a carrier gas.
- the transparent glass rod 500 is rotated in the direction indicated by the arrow S5, and the burner 520 moves a plurality of times along the direction indicated by the arrow S6.
- K element is diffused and added to the inner surface of the hole 510 formed in the transparent glass rod 500.
- the rod-in collaps in step ST ⁇ b> 70 is a solidification of the transparent glass rod 500 (step ST ⁇ b> 71), and the formation of the peripheral core portion on the solidified transparent glass rod (center rod 600). (Step ST72) and a stretching process (Step ST73). That is, the transparent glass rod 500 to which the alkali metal is added in step ST60 is solidified in step ST71, and the center rod 600 is obtained.
- step ST72 of FIG. 6 the center rod 600 obtained in step ST71 is inserted into the insertion hole 625 formed in the glass tube 620 to be the peripheral core portion along the direction indicated by the arrow S8.
- the center rod 600 and the glass tube 620 are integrated by heating.
- the rod-in collapse method in step ST72 may be performed a plurality of times.
- the core preform 110 having a desired outer diameter is obtained by stretching the integrated rod.
- the core base material 110 includes a central core portion 111 and a peripheral core portion 112, and the central core portion 111 is a region corresponding to the above-described central rod 600.
- step ST90 in which the cladding part is provided on the outer periphery of the core base material 110 manufactured as described above, first, the outer periphery of the core base material 110 is subjected to the type B OVD method shown in FIG. A porous body (soot body) is deposited. Subsequently, the obtained porous body is subjected to a dehydration process, a sintering process (glass clarification), and a stretching process by the apparatus shown in FIG. 3 to obtain an optical fiber preform having a predetermined outer diameter. .
- the obtained optical fiber preform is subjected to a second annealing process (step ST100).
- This second annealing process is also performed by the annealing apparatus shown in FIG. 4, but the annealing time may be a fixed time (for example, 5 hours) regardless of the outer diameter of the optical fiber preform.
- the annealing temperature is about 1050 ° C. Therefore, the annealing time of the second annealing process may be shorter than the annealing time of the first annealing process (step ST60).
- FIG. 7 shows the optical fiber preform 100 that has been subjected to the second annealing described above.
- the optical fiber preform 100 after the second annealing treatment includes a core preform 110 and a cladding portion 120 provided on the outer periphery thereof.
- the core base material 110 includes a central core portion 111 (corresponding to the central rod 600 in FIG. 6) to which an alkali metal is added, and a peripheral core portion 112.
- a part 100A of the optical fiber preform 100 is cut from the optical fiber preform 100 as a sample preform.
- the residual He concentration in a region (center core portion 111) corresponding to the center rod of the cut sample base material 100A is measured. Further, the measured residual He concentration is added to the result data 700 together with the annealing time for the first annealing process determined in step ST30.
- FIG. 8 shows an example of the refractive index distribution of the optical fiber preform 100 manufactured as described above.
- the refractive index profile 150 shown in FIG. 8 no impurity for adjusting the refractive index is added to the core portion (core base material) 110, but F is added to the cladding portion 120.
- the refractive index of the cladding part is set lower than the refractive index of the core part 110.
- the performance data 700 used in the annealing time determination step of step ST30 is, for example, as shown in FIG. 9, after annealing time and annealing processing for each outer diameter of the center rod (corresponding to the center core portion 111).
- the relationship of the residual He concentration is recorded.
- the actual data 700 is added with the measured values of the annealing time and the residual He concentration determined in step ST30 every time the optical fiber preform 100 is manufactured, that is, every time the measurement process of step ST110 is performed. , Updated from time to time.
- the heat treatment time on the horizontal axis means the annealing time
- the He concentration on the vertical axis means the residual He concentration.
- the annealing time for the center rod of the outer diameter RT Is determined. That is, when the outer diameter R of the center rod whose relationship between the residual He concentration C [weight ppm] and the annealing time T [hour] is known is set as the reference outer diameter (the center rod having the outer diameter R is referred to as the reference rod).
- An optical fiber is obtained by drawing the optical fiber preform 100 manufactured as described above. That is, as shown in FIG. 11, one end of the optical fiber preform 100 is drawn in the direction indicated by the arrow S ⁇ b> 9 while being heated by the heater 900, so that the refractive index distribution shown in FIG. An optical fiber having the same shape is obtained.
- DESCRIPTION OF SYMBOLS 100 Optical fiber base material, 110 ... Core base material (core part), 111, 600 ... Center rod (center core part), 112 ... Peripheral core part, 120 ... Cladding part, 230, 520 ... Burner, 410, 900 ... Heater, 420 ... thermometer, 430 ... temperature controller, 700 ... result data (including He concentration-time table).
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- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Description
最初に本願発明の実施形態の内容をそれぞれ個別に列挙して説明する。
本願発明に係る光ファイバ母材の製造方法および光ファイバ母材の具体例を、以下に添付の図面を参照しながら詳細に説明する。なお、本発明は、これら例示に限定されるものではなく、特許請求の範囲によって示され、また、特許請求の範囲と均等の意味および範囲内での全ての変更が含まれることが意図されている。また、図面の説明において同一の要素には同一符号を付して重複する説明を省略する。
Claims (4)
- 長手方向に沿ってアルカリ金属の添加領域が形成された中心ロッドを含む、シリカガラスを主成分とするコア母材と、前記コア母材の外周に設けられた、シリカガラスを主成分とするクラッド部と、を備えた光ファイバ母材の製造方法であって、
前記長手方向に沿ってガラス微粒子が堆積された多孔質ロッドに対するClガスを含む雰囲気中での脱水処理、および、前記脱水処理後の多孔質ロッドに対するHeガスを含む雰囲気中での焼結を経て得られる、前記中心ロッドとなるべき所定外径の透明ガラスロッドを製造するロッド製造工程と、前記長手方向に沿って、前記透明ガラスロッド内に前記アルカリ金属を添加する添加工程と、前記添加工程を経て得られた前記中心ロッドの外周に周辺コア部を形成する拡径工程と、を含むコア母材製造工程と、
前記コア母材製造工程を経て得られた前記コア母材の外周に前記クラッド部を形成するクラッド部製造工程と、
前記クラッド部製造工程を経て得られた前記光ファイバ母材から切り出されたサンプル母材のうち、前記中心ロッドに相当する領域内における残留He濃度を測定する測定工程と、を備え、
前記コア母材製造工程は、前記ロッド製造工程と前記添加工程との間に行われる工程として、前記透明ガラスロッドの特定外径に依存する、アニール時間と残留He濃度との関係を示すテーブルを含む実績データを参照して、前記透明ガラスロッドに対するアニール処理の時間を決定するアニール時間決定工程と、少なくとも決定された前記アニール時間、前記Heガスを含まない雰囲気中で前記透明ガラスロッドをアニールする第1アニール処理工程と、を含み、
前記測定工程は、前記第1アニール処理工程においてアニール対象となった前記透明ガラスロッドに関する外径ごとの処理実績として、前記アニール時間決定工程により決定されたアニール時間と、測定された前記残留He濃度を追加していくことにより、前記実績データを更新する、
ことを特徴とする光ファイバ母材の製造方法。 - 前記クラッド部製造工程と前記測定工程の間において、前記クラッド部製造工程を経て得られた前記光ファイバ母材を、前記Heガスを含まない雰囲気中で所定時間だけアニールする第2アニール処理工程を更に備えたことを特徴とする請求項1に記載の光ファイバ母材の製造方法。
- 前記第1アニール処理工程におけるアニール時間が、前記第2アニール処理工程におけるアニール時間よりも長いことを特徴とする請求項2に記載の光ファイバ母材の製造方法。
- 長手方向に沿ってアルカリ金属の添加領域が形成された中心ロッドを含む、シリカガラスを主成分とするコア母材と、前記コア母材の外周に設けられた、シリカガラスを主成分とするクラッド部と、を備えた光ファイバ母材であって、
前記中心ロッドにおけるCl濃度の最大値が1000ppm以下であり、かつ、前記中心ロッドにおける残留He濃度の最大値が0.15[重量ppm]以下であることを特徴とする光ファイバ母材。
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JP2019519127A JP7070561B2 (ja) | 2017-05-15 | 2018-04-13 | 光ファイバ母材の製造方法および光ファイバ母材 |
CN201880031335.6A CN110636992B (zh) | 2017-05-15 | 2018-04-13 | 光纤母材的制造方法及光纤母材 |
DKPA201970751A DK180664B1 (en) | 2017-05-15 | 2019-12-06 | Method for producing optical fiber preform, and optical fiber preform |
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