WO2013118389A1 - 光ファイバ母材製造方法、光ファイバ母材、及び、光ファイバ - Google Patents
光ファイバ母材製造方法、光ファイバ母材、及び、光ファイバ Download PDFInfo
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- WO2013118389A1 WO2013118389A1 PCT/JP2012/082369 JP2012082369W WO2013118389A1 WO 2013118389 A1 WO2013118389 A1 WO 2013118389A1 JP 2012082369 W JP2012082369 W JP 2012082369W WO 2013118389 A1 WO2013118389 A1 WO 2013118389A1
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- alkali metal
- optical fiber
- metal salt
- raw material
- glass pipe
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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]
- C03B37/018—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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
- C03B37/01815—Reactant deposition burners or deposition heating means
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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]
- C03B37/018—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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
-
- 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
- C03B2201/075—Hydroxyl ion (OH)
-
- 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
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
-
- 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
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
- C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with 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
- C03B2201/20—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
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/80—Feeding the burner or the burner-heated deposition site
- C03B2207/90—Feeding the burner or the burner-heated deposition site with vapour generated from solid glass precursors, i.e. by sublimation
Definitions
- the present invention relates to an optical fiber preform manufacturing method, an optical fiber preform, and an optical fiber.
- a diffusion method is known as a method of adding an alkali metal element into quartz glass (see, for example, Patent Documents 1 and 2).
- the diffusion method is to heat the glass pipe with an external heat source or generate plasma in the glass pipe while introducing the raw material vapor such as alkali metal element or alkali metal salt as the raw material into the glass pipe.
- An alkali metal element is diffusely added to the inner surface of the glass pipe.
- the glass pipe After adding the alkali metal element in the vicinity of the inner surface of the glass pipe in this way, the glass pipe is heated to reduce the diameter. After the diameter reduction, the thickness of the inner surface of the glass pipe is etched for the purpose of removing transition metal elements and the like (for example, Ni and Fe) that are added simultaneously with the addition of the alkali metal element. After etching, the glass pipe is heated and solidified to produce an alkali metal element-added core rod. An optical fiber preform is manufactured by synthesizing a clad portion outside the alkali metal element-added core rod. And an optical fiber can be manufactured by drawing this optical fiber preform.
- transition metal elements and the like for example, Ni and Fe
- the diffusion coefficient of alkali metal elements in quartz glass is one digit or more larger than the diffusion coefficient of transition metal elements such as Ni and Fe. That is, the alkali metal element diffuses faster than the transition metal element. Therefore, in the above etching step, even if the glass surface is etched to a certain thickness to remove the transition metal element, it is possible to leave the alkali metal element added to the quartz glass. However, since the diffusion coefficient of the alkali metal element and the diffusion coefficient of the OH group in the quartz glass are about the same, if the OH group is added simultaneously in the step of diffusing the alkali metal element, the alkali metal element remains. However, it is difficult to completely remove the OH group.
- alkali metal salt raw materials are highly hygroscopic and often contain a large amount of adsorbed water, and sometimes contain hydrated water.
- Patent Document 1 describes that KBr as an alkali metal salt raw material was heated to a temperature of 1000 ° C., melted and dehydrated.
- the KBr vapor pressure at a temperature of 1000 ° C. is as high as 3 kPa, there is a problem that a large amount of raw material is consumed simultaneously with dehydration.
- the alkali metal salt raw material is melted, the alkali metal element and moisture may react to form an alkali hydroxide. Further, if the temperature is 550 ° C. or higher, quartz glass and moisture may react to form Si—OH groups.
- the optical fiber in which the alkali metal element is added to the core may contain a relatively large amount of OH groups, and there is a problem that the transmission loss in the wavelength 1.38 ⁇ m band may be increased.
- the present invention has been made to solve the above-described problems, and is an optical fiber mother suitable for manufacturing an optical fiber to which an alkali metal element is added and having a low transmission loss in a wavelength of 1.38 ⁇ m band by drawing.
- An object is to provide a method by which a material can be produced.
- An optical fiber preform manufacturing method includes (1) an alkali metal salt vapor generated by heating an alkali metal salt raw material having an average particle diameter of 1 mm or less and heating the alkali metal salt raw material. Is supplied to the inside of the glass pipe from one end side of the quartz-based glass pipe together with the carrier gas, and the glass pipe is heated by a heat source that moves relatively in the longitudinal direction of the glass pipe to oxidize the alkali metal to cause the glass pipe to be oxidized. A thermal diffusion process for thermally diffusing inside, (2) a solidification process for producing a core rod by solidifying the glass pipe after the thermal diffusion process, and (3) a core rod produced by this solidification process. And a clad part adding step of adding a clad part to the periphery of the substrate.
- the optical fiber preform manufacturing method can include a drying step of heating and drying the alkali metal salt raw material at a temperature of 270 ° C. or higher before the thermal diffusion step.
- the alkali metal salt raw material can be heated and dried at a temperature lower than the melting point of the alkali metal salt raw material.
- the drying step includes a first drying step of heating and drying the alkali metal salt raw material at a temperature below the melting point of the alkali metal salt raw material, and an alkali at a temperature equal to or higher than the melting point of the alkali metal salt raw material after the first drying step.
- a second drying step of heating and drying the metal salt raw material can include a drying step of heating and drying the alkali metal salt raw material at a temperature of 270 ° C. or higher before the thermal diffusion step.
- the glass pipe may contain chlorine (Cl) and fluorine as additives, and the average concentration of chlorine and fluorine may be 10 atomic ppm or more, and the concentration of other additives may be 10 atomic ppm or less. Further, in the thermal diffusion step, the alkali metal can be thermally diffused inside the glass pipe so that the alkali metal concentration is 500 atomic ppm or more at the maximum value.
- the optical fiber preform according to one aspect of the present invention is manufactured by the above-described optical fiber preform manufacturing method according to one aspect of the present invention, and the average concentration of OH groups in the core portion is 0.002 mol ⁇ ppm or less. It is characterized by.
- An optical fiber according to an aspect of the present invention is manufactured by drawing the optical fiber preform according to the above-described aspect of the present invention, and an increase in transmission loss due to OH group absorption in a wavelength of 1.38 ⁇ m band is 0.1 dB. / Km or less.
- an optical fiber preform suitable for manufacturing an optical fiber to which an alkali metal element is added and has a low transmission loss in the wavelength 1.38 ⁇ m band.
- the optical fiber preform manufacturing method of the present embodiment includes a drying process, a thermal diffusion process, a solidification process, and a cladding part adding process.
- the drying step the alkali metal salt raw material having an average particle diameter of 1 mm or less, preferably 0.5 mm or less, is heated and dried at a temperature of 270 ° C. or higher and lower than the melting point.
- the thermal diffusion process the alkali metal salt vapor generated by heating the alkali metal salt raw material is supplied into the glass pipe from the one end side of the quartz-based glass pipe together with the carrier gas, and is relative to the longitudinal direction of the glass pipe.
- the glass pipe is heated by a heat source that moves to, and an alkali metal element is oxidized and thermally diffused inside the glass pipe.
- the glass rod after the thermal diffusion process is solidified to produce a core rod.
- the cladding portion adding step the cladding portion is added around the core rod manufactured in the solidification step to manufacture an optical fiber preform.
- the average particle diameter of the alkali metal salt raw material in this embodiment was measured by acquiring an image of the alkali metal salt raw material with an optical microscope and converting the image image into the size of the particles of the alkali metal salt raw material.
- the number of alkali metal salt raw material particles measured here was several thousand, and the median value (median value) of the particle size distribution was defined as the average particle size.
- FIG. 1 is a graph showing the results of temperature-programmed desorption gas analysis (TDS) in a nitrogen atmosphere for potassium bromide (KBr) as an alkali metal salt raw material.
- TDS temperature-programmed desorption gas analysis
- KBr potassium bromide
- the KBr used at this time was crystalline and had a particle size of about 3 mm.
- the alkali metal raw material is heated from 270 ° C. to 600 ° C. over 10 minutes and then kept at 600 ° C.
- moisture desorption is reduced to almost the background level by heating for about 20 minutes. This indicates that the amount of adsorbed water near the surface of the KBr solid starts rapid desorption at around 270 ° C. and can be removed by heating at 270 ° C. or higher for 30 minutes.
- FIG. 2 is a graph showing the relationship between temperature and desorbed water content for potassium bromide (KBr) as an alkali metal salt raw material. As shown in the figure, it can be seen that the desorption rate does not increase at a temperature of 270 ° C. or higher. Thus, it is preferable to treat the alkali metal salt raw material at a temperature of 270 ° C. or higher.
- the particle diameter of the alkali metal salt raw material may be reduced and the surface area per volume of the alkali metal salt raw material may be increased.
- the particle diameter D corresponds to the diameter of the sphere, so the surface area per volume is 6 / D. Therefore, the smaller the particle diameter D, the larger the surface area per volume, the more the adsorbed water on the solid surface of the alkali metal salt raw material than the hydrated water contained in the solid of the alkali metal salt raw material, and the easier the drying. Become.
- FIG. 5 is a diagram for explaining a thermal diffusion process in the optical fiber preform manufacturing method.
- the quartz glass pipe 1 used contains 100 atomic ppm of Cl and 6,000 atomic ppm of fluorine, the concentration of other additives is below the detection limit (about 1 ppm), and the outer diameter is 32 mm. The inner diameter was 15 mm.
- a handling glass pipe 5 was connected to one end of the glass pipe 1, a part of the handling glass pipe 5 was used as a raw material reservoir, and an alkali metal salt raw material 3 was installed in the raw material reservoir.
- the first comparative example was prototyped with an average particle size of KBr, which is an alkali metal salt raw material, of about 3 mm.
- a prototype of the second comparative example was made with an average particle size of KBr, which is an alkali metal salt raw material, of about 1.5 mm.
- the prototype of the first example was made with the average particle size of KBr, which is an alkali metal salt raw material, being about 1.0 mm.
- a prototype of the second example was made with the average particle size of KBr as the alkali metal salt raw material being about 0.5 mm.
- a prototype of the third example was made by setting the average particle size of KBr, which is an alkali metal salt raw material, to about 0.2 mm. A part of the glass pipe 1 may be used as a raw material reservoir.
- 3 SLM (3 L / min converted to the standard state) of dry nitrogen (dew point of ⁇ 76 ° C. or less) as a carrier gas is introduced into the raw material reservoir, while the external heat source (electric furnace) 2 supplies the outside of the raw material reservoir.
- the alkali metal salt raw material 3 in the raw material reservoir was dried by maintaining the state heated to 500 ° C. for 30 minutes.
- the temperature of the raw material reservoir is adjusted to 860 ° C., and 1 SLM dry oxygen is introduced into the raw material reservoir and the glass pipe 1 as a carrier gas so that the outer surface of the glass pipe 1 reaches a temperature of 2000 ° C. Heated by an external heat source (oxyhydrogen burner) 4.
- oxyhydrogen burner was moved at a speed of 30 mm / min, and this was carried out a total of 15 times to diffuse potassium to the inner surface of the glass pipe.
- the glass pipe 1 in which the alkali metal element was diffused was heated by the oxyhydrogen burner 4 so that the inner diameter was reduced to about 4 mm.
- the glass pipe 1 is heated to a temperature of 2000 ° C. with an oxyhydrogen burner 4 while supplying SF 6 and Cl 2 from the gas supply unit to the glass pipe 1, so that the inner surface has a diameter of about 5 mm. Vapor phase etching of the inner surface of the glass pipe 1 was performed until it was.
- the glass pipe 1 to which the alkali metal element has been added is heated to about 1400 ° C. with the oxyhydrogen burner 4 while evacuating the internal pressure in the pipe to about 100 kPa in absolute pressure.
- solidification was performed to obtain an alkali metal-added glass rod having an outer diameter of about 25 mm.
- the outside of the glass rod is sufficiently ground until the OH group disappears (specifically, until the outer diameter becomes about 70% or less after the solidification).
- a core rod was used.
- a second core having a diameter about three times the diameter of the first core rod was provided outside the first core rod.
- the second core rod is made of a silica-based glass to which Cl is added on an average of 6,000 ppm and other additives are 1 ppm or less.
- a quartz-based glass in which the first core and the second core were combined to form a core portion, and further, fluorine element serving as a first cladding portion was added to the outside thereof was synthesized.
- the relative refractive index difference of the first clad portion with respect to the second core portion was about ⁇ 0.33% when the refractive index of the first clad portion was the smallest.
- a silica-based glass doped with fluorine having a relative refractive index difference with respect to the second core portion of about ⁇ 0.23% is synthesized as a second cladding portion, and this is combined with an optical fiber preform. did.
- optical fiber preform optical fibers according to the first and second comparative examples and the first to third examples were manufactured.
- FIG. 4 is a graph showing the relationship between transmission loss increase ⁇ OH (see FIG. 3) due to OH group absorption at a wavelength of 1.38 ⁇ m in each optical fiber and the particle size of the alkali metal salt raw material.
- the transmission loss increase ⁇ OH is 0.31 dB, respectively. / Km, about 0.27 dB / km.
- the transmission loss increase ⁇ OH is 0.062 dB / km, 0.013 dB / km, and 0.014 dB / km.
- the average particle size of the alkali metal salt raw material is desirably about 1 mm or less.
- the OH group is present at 1 mol ⁇ ppm in the core portion of the silica glass optical fiber, it is said that it has an absorption loss ⁇ OH of about 60 dB / km in the wavelength 1.3 ⁇ m band. Therefore, when the absorption loss ⁇ OH is 0.1 dB / km or less, the average concentration of OH groups in the core portion of the optical fiber preform is 0.002 mol ⁇ ppm or less.
- This OH group is not only an OH group mixed from the alkali metal salt raw material, but also an optical fiber preform such as a process of performing thermal diffusion of an alkali metal element or a solidification process of a quartz glass pipe to which an alkali metal element is added. All OH groups in the core of the optical fiber preform are included, such as OH group contamination in the manufacturing process and OH groups contained in the quartz glass pipe itself used as the substrate.
- the average particle size of the alkali metal salt raw material is about 0.5 mm or less, the absorption loss ⁇ OH due to OH groups is 0.05 dB / km or less, and the average concentration in the core portion of the optical fiber preform is 0.001 mol ⁇ ⁇ . It is below ppm and is extremely reduced. Therefore, the average particle size of the alkali metal salt raw material is more preferably 0.5 mm or less.
- the optical fibers according to the first to third examples have a difference in transmission loss increase ⁇ OH due to OH group absorption at a wavelength of 1.38 ⁇ m as shown in FIG. 4 due to the difference in particle size of the raw material KBr. It had the following common characteristics.
- the potassium addition concentration (average value in the core) was about 2 atomic ppm.
- the transmission loss (wavelength 1300 nm) was 0.285 to 0.300 dB / km, and the transmission loss (wavelength 1550 nm) was 0.155 to 0.165 dB / km.
- the chromatic dispersion (wavelength 1550 nm) was +20.0 to +21.5 ps / nm / km, and the dispersion slope (wavelength 1550 nm) was +0.055 to +0.065 ps / nm 2 / km.
- the effective area (wavelength 1550 nm) was 125 to 145 ⁇ m 2 and the mode field diameter (wavelength 1550 nm) was 12 to 14 ⁇ m.
- the fiber cutoff wavelength (2 m) was 1400-1600 nm, and the cable cutoff wavelength (2 m) was 1300-1500 nm.
- Polarization mode dispersion (C and L bands) is 0.001 to 0.15 ps / ⁇ km, and nonlinear refractive index (wavelength 1550 nm, random polarization state) N2 is 2.1 to 2.2 ⁇ 10 ⁇ 20 m. 2 / W, and the nonlinear coefficient (wavelength 1550 nm, random polarization state) was 0.6 to 0.7 (W ⁇ km) ⁇ 1 .
- an optical fiber with low transmission loss was obtained.
- an optical fiber is manufactured using an optical fiber preform including an alkali metal-added silica glass rod manufactured by thermal diffusion of an alkali metal element into a silica glass pipe as a core part or a part of the core part.
- an alkali metal salt having an average particle diameter of about 1 mm or less as the raw material of the alkali metal element, the absorption loss increase ⁇ OH due to the OH group in the optical fiber is 0.1 dB / km or less, preferably 0.3. It is possible to reduce it to 05 dB / km or less.
- the alkali metal salt raw material is preferably dried at a temperature of 270 ° C. or higher and lower than the melting point of the alkali metal salt raw material (preferably 550 ° C. or lower).
- the alkali metal salt raw material desorbs the hydrated water contained therein at its melting point. Complete removal is considered difficult by drying at temperatures below the melting point. Therefore, the alkali metal salt raw material having a particle size of 1 mm or less is dried at a temperature of 270 ° C. or higher and lower than the melting point of the alkali metal salt raw material (preferably 550 ° C.
- the moisture present in the alkali metal salt raw material is It is more preferable to desorb the adsorbed water on the surface that occupies most of the surface, and then dry the alkali metal salt raw material at a temperature equal to or higher than the melting point of the alkali metal salt raw material to slightly desorb the hydrated water inside the raw material. It is thought that.
- the average particle diameter of KBr which is an alkali metal salt raw material was set to about 1 mm.
- the drying process is different from the method mentioned above. That is, in this trial drying process, first, an external heat source (electric furnace) is introduced while introducing dry nitrogen (dew point of ⁇ 76 ° C. or less) of carrier gas 3SLM (3 L / min in terms of standard state) into the raw material reservoir. The first drying step of drying the alkali metal salt raw material 3 in the raw material reservoir was performed by maintaining the state where the outside of the raw material reservoir was heated to 500 ° C. for 30 minutes.
- 3SLM dry nitrogen was introduced into the raw material reservoir as a carrier gas while the temperature of the external heat source (electric furnace) 2 was raised to 750 ° C. and the alkali metal salt raw material 3 was melted.
- the second drying step was carried out for 5 minutes.
- the prototype drying process of the fourth embodiment includes a first drying process in which the alkali metal salt raw material 3 is heated and dried at a temperature lower than the melting point of the alkali metal salt raw material 3 (for example, 500 ° C.), And a second drying step of heating and drying the alkali metal salt raw material 3 at a temperature equal to or higher than the melting point of the alkali metal salt raw material 3 (for example, 750 ° C.).
- the transmission loss increase ⁇ OH (see FIG. 3) due to OH group absorption at the wavelength of 1.38 ⁇ m of the optical fiber according to the fourth embodiment obtained in this way is as low as 0.011 dB / km. As a result. This further reduces the transmission loss increase ⁇ OH of the optical fiber according to the first embodiment, in which the average particle diameter of the alkali metal salt raw material is about 1.0 mm, from 0.062 dB / km.
- the increase in transmission loss ⁇ OH at other wavelengths of the optical fiber according to the fourth example was 0.286 dB / km at a wavelength of 1300 nm and 0.156 dB / km at a wavelength of 1550 nm.
- the drying step after performing the first drying step at a temperature of 270 ° C. or higher and lower than the melting point of the alkali metal salt raw material (preferably 550 ° C. or lower), the melting point of the alkali metal salt raw material or higher is achieved. It is preferable to carry out the second drying step at a temperature of.
- the core of the optical fiber preform contains an alkali metal element, Cl or fluorine, but it is desirable that the concentration of other additives such as transition metals such as Ge, Al, P, Fe, Ni, and Cu be as small as 1 ppm or less. By doing so, it is possible to reduce the transmission loss of the optical fiber at a wavelength of 1550 nm to 0.18 dB / km or less. In this case, it is desirable to use quartz-based glass to which fluorine is added as the cladding portion of the optical fiber preform so that the refractive index of the cladding portion is lower than the average refractive index of the core portion.
- the core of the optical fiber preform preferably contains an alkali metal element having a peak value of 500 atomic ppm or more.
- the transmission loss at a wavelength of 1550 nm of an optical fiber manufactured using this optical fiber preform can be reduced to 0.17 dB / km.
- the structure and characteristics of the optical fiber are as follows, for example.
- the transmission loss of the optical fiber at a wavelength of 1550 nm is preferably as low as 0.180 dB / km or less, more preferably 0.170 dB / km or less, and further preferably 0.160 dB / km or less.
- the effective area may be about 70 to 160 ⁇ m 2 at a wavelength of 1550 nm.
- the chromatic dispersion at the wavelength of 1550 nm may be +15 to +22 ps / nm / km.
- the zero dispersion wavelength may be 1250 nm or more and 1350 nm or less.
- the dispersion slope may be +0.05 to +0.07 ps / nm 2 / km at a wavelength of 1550 nm.
- the transmission loss at a wavelength of 1380 nm is preferably as low as 0.8 dB / km or less, more preferably 0.4 dB / km or less, and most preferably 0.3 dB / km or less.
- the polarization mode dispersion in the wavelength 1550 nm band may be 0.2 ps / ⁇ km or less.
- the cable cutoff wavelength is preferably 1530 nm or less, more preferably 1450 nm or less, which is a pump wavelength used for Raman amplification, and may be 1260 nm or less as in a standard single mode fiber.
- the diameter of the core part is about 5 to 15 ⁇ m, and the relative refractive index difference between the core part and the cladding part ((core part refractive index ⁇ cladding part refractive index) / core part refractive index) is about 0.1 to 0.7%. It is.
- the diameter of the outer circumference of the glass portion of the optical fiber may be about 110 to 150 ⁇ m, and the diameter of the outer circumference of the optical fiber coated with resin is preferably about 200 to 300 ⁇ m.
- Such an optical fiber is suitably used particularly as an optical transmission line of an optical transmission system for long-distance optical communication.
- an optical fiber preform suitable for manufacturing an optical fiber to which an alkali metal element is added and has a low transmission loss in the wavelength 1.38 ⁇ m band.
Abstract
Description
Claims (8)
- 平均粒径が1mm直径以下であるアルカリ金属塩原料を用い、このアルカリ金属塩原料を加熱して生成したアルカリ金属塩の蒸気をキャリアガスとともに石英系のガラスパイプの一端側から前記ガラスパイプの内部に供給し、前記ガラスパイプの長手方向に相対的に移動する熱源により前記ガラスパイプを加熱して、アルカリ金属を酸化反応させて前記ガラスパイプの内側に熱拡散させる熱拡散工程と、
この熱拡散工程後の前記ガラスパイプを中実化してコアロッドを作製する中実化工程と、
この中実化工程で作製されたコアロッドの周囲にクラッド部を付加するクラッド部付加工程と、
を備えることを特徴とする光ファイバ母材製造方法。 - 前記熱拡散工程の前に前記アルカリ金属塩原料を270℃以上の温度で加熱して乾燥する乾燥工程を備える、ことを特徴とする請求項1に記載の光ファイバ母材製造方法。
- 前記乾燥工程において、前記アルカリ金属塩原料の融点未満の温度で前記アルカリ金属塩原料を加熱して乾燥する、ことを特徴とする請求項2に記載の光ファイバ母材製造方法。
- 前記乾燥工程は、前記アルカリ金属塩原料の融点未満の温度で前記アルカリ金属塩原料を加熱して乾燥する第1の乾燥工程と、前記第1の乾燥工程の後に、前記アルカリ金属塩原料の融点以上の温度で前記アルカリ金属塩原料を加熱して乾燥する第2の乾燥工程と、を含む、ことを特徴とする請求項2に記載の光ファイバ母材製造方法。
- 前記ガラスパイプが塩素およびフッ素を含み、塩素およびフッ素それぞれの平均濃度が10原子ppm以上であり、その他の添加剤の濃度が10原子ppm以下である、ことを特徴とする請求項1~4の何れか1項に記載の光ファイバ母材製造方法。
- 前記熱拡散工程において、アルカリ金属の濃度が最大値で500原子ppm以上となるようにアルカリ金属を前記ガラスパイプの内側に熱拡散させる、ことを特徴する請求項1~5の何れか1項に記載の光ファイバ母材製造方法。
- 請求項1~6の何れか1項に記載の光ファイバ母材製造方法により製造され、コア部のOH基の平均濃度が0.002mol・ppm以下である、ことを特徴とする光ファイバ母材。
- 請求項7に記載の光ファイバ母材を線引することで製造され、波長1.38μm帯におけるOH基吸収による伝送損失増が0.1dB/km以下である、ことを特徴とする光ファイバ。
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EP12867846.3A EP2813477B1 (en) | 2012-02-09 | 2012-12-13 | Optical fiber preform manufacturing method, optical fiber preform, and optical fiber |
US14/376,929 US9340444B2 (en) | 2012-02-09 | 2012-12-13 | Optical fiber preform manufacturing method, optical fiber preform, and optical fiber |
CN201280069472.1A CN104159858B (zh) | 2012-02-09 | 2012-12-13 | 光纤母材制造方法、光纤母材以及光纤 |
DK12867846.3T DK2813477T3 (en) | 2012-02-09 | 2012-12-13 | METHOD FOR MANUFACTURING OPTICAL FIBER PREFORM, OPTICAL FIBER PREFORM, AND OPTICAL FIBER |
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CN103472529A (zh) * | 2013-09-10 | 2013-12-25 | 烽火通信科技股份有限公司 | 低损耗光纤及其制造方法 |
WO2016021576A1 (ja) * | 2014-08-06 | 2016-02-11 | 古河電気工業株式会社 | 光ファイバ母材および光ファイバの製造方法 |
WO2018110234A1 (ja) | 2016-12-12 | 2018-06-21 | 住友電気工業株式会社 | 光ファイバ母材製造方法、光ファイバ母材、および光ファイバ |
WO2019044833A1 (ja) * | 2017-08-31 | 2019-03-07 | 住友電気工業株式会社 | 光ファイバ母材の製造方法、及び、光ファイバの製造方法 |
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JP5903896B2 (ja) * | 2012-01-11 | 2016-04-13 | 住友電気工業株式会社 | 光ファイバ母材製造方法 |
CN111007593B (zh) * | 2019-05-12 | 2022-05-13 | 桂林电子科技大学 | 基于热扩散融嵌芯毛细管光纤微小粒子输运装置 |
JP7159974B2 (ja) * | 2019-05-23 | 2022-10-25 | 住友電気工業株式会社 | 光ファイバの製造方法、および光ファイバの製造装置 |
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CN104159858B (zh) | 2016-08-24 |
CN104159858A (zh) | 2014-11-19 |
DK2813477T3 (en) | 2017-09-11 |
EP2813477A4 (en) | 2015-10-14 |
US20150299022A1 (en) | 2015-10-22 |
US9340444B2 (en) | 2016-05-17 |
JPWO2013118389A1 (ja) | 2015-05-11 |
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EP2813477A1 (en) | 2014-12-17 |
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