CN1782756B - Optical fiber preform, method of manufacturing optical fiber preform, and method of manufacturing optical fiber - Google Patents

Optical fiber preform, method of manufacturing optical fiber preform, and method of manufacturing optical fiber Download PDF

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Publication number
CN1782756B
CN1782756B CN 200510126996 CN200510126996A CN1782756B CN 1782756 B CN1782756 B CN 1782756B CN 200510126996 CN200510126996 CN 200510126996 CN 200510126996 A CN200510126996 A CN 200510126996A CN 1782756 B CN1782756 B CN 1782756B
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optical fiber
glass
layer
mother metal
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CN1782756A (en
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折田伸昭
金尾昭博
森平英也
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Furukawa Electric Co Ltd
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Furukawa Electric Co Ltd
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Priority claimed from JP2005117310A external-priority patent/JP4776263B2/en
Priority claimed from JP2005241301A external-priority patent/JP5242006B2/en
Priority claimed from JP2005241302A external-priority patent/JP5242007B2/en
Application filed by Furukawa Electric Co Ltd filed Critical Furukawa Electric Co Ltd
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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
    • C03B37/01205—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
    • C03B37/014—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]
    • C03B37/01413—Reactant delivery systems
    • 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
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/10—Internal structure or shape details
    • C03B2203/22—Radial profile of refractive index, composition or softening point

Abstract

The invention relates to a manufacturing method which does not use expensive helium gas to manufacture the large-scale optical fiber base metal, and can strive for reducing the manufacturing cost of the optical fiber base metal. The method comprises the following steps that: firstly, a porous base metal layer is formed by depositing glass particles at the periphery of a core rod which contains and has a core layer and presents a rod shape; secondly, the porous base metal layer is dehydrated under at least one condition from the following atmospheres that the pressure is reduced, nonactive gas and halogen gas exist, and the nonactive gas and halide gas exist; thirdly, the dehydrated porous base metal layer is sintered into a translucent glass metal base layer which contains independent air bubbles under the condition that the pressure is reduced; fourthly, the translucent glass metal base layer which contains the independent air bubbles is transparentized in the atmosphere of the nonactive gas (except the helium gas), thereby further becoming an inhibitory coating.

Description

The manufacturing approach of fibre parent material, fibre parent material and optical fiber manufacturing method
Technical field
The present invention relates to have the clad of sandwich layer and this sandwich layer of encirclement, mainly be used in the optical fiber manufacturing method of optical communication and the manufacturing approach of fibre parent material.
Background technology
Recently, except that the light transmission characteristic that improves optical fiber, increase day by day for the requirement that reduces the optical fiber price.
As optical fiber manufacturing method, known gas phase tape spool sedimentation (Vapor-phase Axial Deposition method:VAD method), modified CVD method (Modified Chemical Vapor Deposition method:MCVD method), outside vapour deposition (Outside Vapor Deposition method:OVD method), plasma chemical vapor deposition method (Plasma Chemical Vapor Deposition method:PCVD method), sol-gel process, ロ Star De イ Application チ ユ one Block method (Rod-In-Tube method:RIT method) and the manufacturing approach that makes up these.
But these manufacturing approaches are ripe, and room for improvement is few.Therefore, the reduction of realization manufacturing cost is surely not easy.In addition, present situation is that owing to the manufacturing capacity of the set many optical fiber manufacturing installations of the equipment investment of before and after 2000 Christian eras, extensively carrying out is superfluous, investment of appending or exploitation are also very difficult.And these old-fashioned production equipments become the major reason that hinders the reduction manufacturing cost.
Manufacturing environment about present optical fiber; Owing to be aforesaid situation, therefore, the methods for optical fiber manufacture of expectation is at present; When doing one's utmost the existing manufacturing equipment of fully utilization, and optimal combination technology is in the past cut down the optical fiber manufacturing method of manufacturing cost.
For example; Account in the most clad of optical fiber in formation; To be deposited on the plug periphery with the synthetic quartzy type glass granules that generates of the such gas phase of OVD method and form the porous preform layer, it is heat-treated the method for making clear glass mother metal layer is the excellent process as the manufacturing approach of low-cost and high-quality large-scale optical fiber mother metal.
But; To heat-treat the clear glass makeup that forms clear glass mother metal layer with the synthetic porous layer that forms of the such gas phase of OVD method puts; To prevent that sneaking into the impurity that produces from heater is purpose, typically uses the heating furnace of the stove core barrel with silica glass.But, this stove core barrel the clear glassization of porous layer needed near 1600 ℃ temperature under easy softening transform.And, in particular for making large-scale fibre parent material clear glassization, then need the stove core barrel of particle size, but in this particle size stove core barrel, have the problem of permanance.For addressing this problem, the method that has proposed manufacturing jealous glass mother metal in No. 2565712 communique of Jap.P. is its direct wire drawing to be become the method for optical fiber.
Summary of the invention
The present invention carries out in view of above situation, and its purpose is, the manufacturing approach and the optical fiber manufacturing method of fibre parent material that obtains large-scale fibre parent material and can seek to cut down the manufacturing cost of optical fiber.
For solving above-mentioned problem; Achieve the goal; The manufacturing approach of the fibre parent material that the present invention relates to is to have sandwich layer and around the manufacturing approach of the fibre parent material of the clad of this sandwich layer, this method has following operation: the porous preform layer that forms the porous preform layer at the quartzy type glass granules of periphery deposit that has sandwich layer and be the bar-shaped plug that comprises quartzy type glass forms operation; Under reduced pressure, under the atmosphere of non-active gas and halogen gas, under any one the condition at least of the atmosphere of non-active gas and halogen chemical compound gas with the dehydration procedure of above-mentioned porous preform pull-up water; Above-mentioned porous preform layer sintering after under reduced pressure will dewatering reaches the sintering circuit that becomes the translucent glass mother metal layer that contains separated foam; With in non-active gas (except the helium) atmosphere, will contain the above-mentioned translucent glass mother metal layer clear glassization of separated foam and then become the clear glass chemical industry preface of above-mentioned clad.
In addition; The methods for optical fiber manufacture that the present invention relates to is to have sandwich layer and around the optical fiber manufacturing method of the clad of this sandwich layer, this method has following operation: the porous preform layer that forms the porous preform layer at the quartzy type glass granules of periphery deposit that has sandwich layer and be the bar-shaped plug that comprises quartzy type glass forms operation; Under reduced pressure, under the atmosphere of non-active gas and halogen gas, under any one the condition at least of the atmosphere of non-active gas and halogen chemical compound gas with the dehydration procedure of above-mentioned porous preform pull-up water and the above-mentioned porous preform layer sintering after under reduced pressure will dewatering reach the sintering circuit that becomes the translucent glass mother metal layer that contains separated foam; Carrying out wire drawing with the translucent mother metal that will contain above-mentioned plug and above-mentioned translucent glass mother metal layer makes above-mentioned translucent glass mother metal layer become the wire-drawing process of transparent glass layer.
In addition; The methods for optical fiber manufacture that the present invention relates to is the optical fiber manufacturing method that has sandwich layer and center on the clad of this sandwich layer; This method has following operation: form the porous preform layer at the quartzy type glass granules of the periphery deposit of mandrel; Then above-mentioned mandrel is extracted out from above-mentioned porous preform layer, made the production process of the tubular porous plastid of tubular porous plastid; Under reduced pressure, under any one the condition at least of the atmosphere of the atmosphere of non-active gas and halogen gas and non-active gas and halogen chemical compound gas, with the dehydration procedure of above-mentioned tubular porous plastid dehydration; With the above-mentioned tubular porous plastid that will dewater under reduced pressure sintering reach the sintering circuit that becomes the translucent glass cylinder that contains separated foam; Insert the plug insertion operation in the above-mentioned translucent glass cylinder with having above-mentioned sandwich layer and being the bar-shaped plug that comprises quartzy type glass; With the limit the above-mentioned translucent glass cylinder that has inserted above-mentioned plug is heated, the limit wire drawing makes above-mentioned plug and the fusion of above-mentioned translucent glass cylinder is integrated and make above-mentioned translucent glass cylinder become the wire-drawing process of the above-mentioned clad that constitutes clear glass.
Have again; The optical fiber manufacturing method that the present invention relates to be have more than 1 layer or 1 layer sandwich layer and around the optical fiber manufacturing method of the clad more than 1 layer or 1 layer of this sandwich layer, this method has following operation: the periphery deposited glass particulate having above-mentioned sandwich layer and being bar-shaped plug forms the porous preform layer to process the 1st prefabrication production process of the 1st prefabrication; With above-mentioned the 1st prefabrication is carried out processed and sintering processes and the porous preform layer is reached become the dehydration sintering circuit of the translucent glass mother metal layer that contains separated foam; Insert in the glass tube to process the 2nd prefabrication production process of the 2nd prefabrication with above-mentioned the 1st prefabrication that will carry out above-mentioned processed and above-mentioned sintering processes; With the limit above-mentioned the 2nd prefabrication is heated, the limit wire drawing makes above-mentioned translucent glass mother metal layer and above-mentioned glass tube fusion is integrated and make above-mentioned translucent glass mother metal layer become the wire-drawing process of the above-mentioned clad that is made up of clear glass.
In addition; The fibre parent material that the present invention relates to is the fibre parent material that forms at the periphery formation initial package coating of plug; It is characterized in that the initial package coating is the clear glass state that does not contain separated foam for the fore-end that the wire drawing of the inner translucent glass state that contains separated foam, this initial package coating begins side.
Particularly, main points of the present invention are following.
1. the manufacturing approach of a fibre parent material, this method are to have sandwich layer and around the manufacturing approach of the fibre parent material of the clad of this sandwich layer, it is characterized in that having following operation:
Have above-mentioned sandwich layer and be porous preform layer that the bar-shaped quartzy type glass granules of periphery deposit that comprises the plug of quartzy type glass forms the porous preform layer form operation,
Under reduced pressure, under any one condition at least in 3 kinds of environmental baselines of the atmosphere of the atmosphere of non-active gas and halogen gas, non-active gas and halogen chemical compound gas with the dehydration procedure of above-mentioned porous preform pull-up water,
With above-mentioned porous preform layer after will dewatering under the pressure below the 2000Pa sinter to the sintering circuit that becomes the translucent glass mother metal layer that contains separated foam,
With will contain the above-mentioned translucent glass mother metal layer clear glassization of separated foam in the non-active gas atmosphere beyond the helium and then form the clear glass chemical industry preface of above-mentioned clad,
Above-mentioned dehydration procedure is carrying out below 1300 ℃,
Above-mentioned sintering circuit becomes 1.8g/cm in the average density that makes above-mentioned porous preform layer 3More than, not enough 2.2g/cm 3Condition under carry out.
2. according to the manufacturing approach of fibre parent material of above-mentioned 1 record, it is characterized in that,
The inside of contained above-mentioned separated foam is vacuum in the above-mentioned translucent glass mother metal layer.
3. according to the manufacturing approach of fibre parent material of above-mentioned 1 or 2 records, it is characterized in that,
Above-mentioned dehydration procedure and above-mentioned sintering circuit; Carry out through using heating furnace to heat above-mentioned porous preform layer on the whole equably; Described heating furnace is that the stove core barrel that contains quartzy type glass is arranged in the pressure vessel; And be provided with a plurality of well heaters around the above-mentioned stove core barrel and constitute
Clear glass chemical industry preface adopts the heating furnace of the regional type of heating with stove core barrel to carry out, and said stove core barrel is made up of any of quartzy type glass and carbon.
4. optical fiber manufacturing method, this method are to have sandwich layer and around the optical fiber manufacturing method of the clad of this sandwich layer, it is characterized in that having following operation:
Have above-mentioned sandwich layer and be porous preform layer that the bar-shaped quartzy type glass granules of periphery deposit that comprises the plug of quartzy type glass forms the porous preform layer form operation,
Under reduced pressure, under any one condition at least in 3 kinds of environmental baselines of the atmosphere of the atmosphere of non-active gas and halogen gas, non-active gas and halogen chemical compound gas with the dehydration procedure of above-mentioned porous preform pull-up water,
With above-mentioned porous preform layer after will dewatering under the pressure below the 2000Pa sinter to the sintering circuit that becomes the translucent glass of the separated foam that contains vacuum mother metal layer,
Carry out wire drawing with the translucent glass mother metal that will contain above-mentioned plug and above-mentioned translucent glass mother metal layer and make above-mentioned translucent glass mother metal layer become the wire-drawing process of transparent glass layer,
Above-mentioned dehydration procedure is carrying out below 1300 ℃,
Above-mentioned sintering circuit becomes 1.8g/cm in the average density that makes above-mentioned porous preform layer 3More than, not enough 2.2g/cm 3Condition under carry out.
5. methods for optical fiber manufacture, this method are to have sandwich layer and around the optical fiber manufacturing method of the clad of this sandwich layer, it is characterized in that having following operation:
Form the porous preform layer at the quartzy type glass granules of the periphery deposit of mandrel, then above-mentioned mandrel is extracted out from above-mentioned porous preform layer, the production process of the tubular porous plastid of manufacturing tubular porous plastid,
Under reduced pressure, under any one condition at least in 3 kinds of environmental baselines of the atmosphere of the atmosphere of non-active gas and halogen gas and non-active gas and halogen chemical compound gas, with the dehydration procedure of above-mentioned tubular porous plastid dehydration,
With will dewater after above-mentioned tubular porous plastid under reduced pressure sinter to the sintering circuit that becomes the translucent glass cylinder that contains separated foam,
With will have above-mentioned sandwich layer and be the bar-shaped plug that comprises quartzy type glass insert plug in the above-mentioned translucent glass cylinder insert operation,
With the limit the above-mentioned translucent glass cylinder that has inserted above-mentioned plug is heated; The limit wire drawing makes above-mentioned plug and the fusion of above-mentioned translucent glass cylinder is integrated and make above-mentioned translucent glass cylinder become the wire-drawing process of the above-mentioned clad that is made up of clear glass
Above-mentioned dehydration procedure is carrying out below 1300 ℃,
Above-mentioned sintering circuit becomes 1.8g/cm in the average density that makes above-mentioned porous preform layer 3More than, not enough 2.2g/cm 3Condition under carry out.
6. according to the optical fiber manufacturing method of above-mentioned 5 records, it is characterized in that,
The inside of contained above-mentioned separated foam is vacuum in the above-mentioned translucent glass cylinder.
7. according to the optical fiber manufacturing method of above-mentioned 5 records, it is characterized in that,
Above-mentioned dehydration procedure and above-mentioned sintering circuit; Carry out through using heating furnace to heat above-mentioned porous preform layer on the whole equably; Said heating furnace is; The stove core barrel that will contain quartzy type of glass is arranged in the pressure vessel, and around above-mentioned stove core barrel, is provided with a plurality of well heaters and constitutes.
8. according to the optical fiber manufacturing method of above-mentioned 5 records, it is characterized in that,
Insert between operation and the above-mentioned wire-drawing process at above-mentioned plug, the end heating and melting with the wire-drawing direction side of the above-mentioned translucent glass cylinder that has inserted above-mentioned plug makes its being integrally formed state.
According to above-mentioned 8 the record optical fiber manufacturing method; It is characterized in that; As the wire-drawing direction side end of the above-mentioned translucent glass cylinder that will insert above-mentioned plug heating means during heating and melting in advance, use the injection and in the electric furnace type of heating any one of injection, the flame passes of the inflammable gas flame of hydrogen-oxygen, methane.
10. according to the optical fiber manufacturing method of above-mentioned 5 records, it is characterized in that,
In above-mentioned wire-drawing process, between above-mentioned plug of major general and above-mentioned translucent glass cylinder, be set to decompression state.
11. an optical fiber manufacturing method, this method are the optical fiber manufacturing method with sandwich layer more than 1 layer and the clad more than 1 layer that surrounds this sandwich layer, it is characterized in that having following operation:
The periphery deposited glass particulate that has above-mentioned sandwich layer and be bar-shaped plug form the porous preform layer with the 1st prefabrication production process of processing the 1st prefabrication,
With above-mentioned the 1st prefabrication is carried out processed and sintering processes up to the porous preform layer become the translucent glass mother metal layer that contains separated foam the dehydration sintering circuit,
With above-mentioned the 1st prefabrication that will carry out above-mentioned processed and above-mentioned sintering processes insert in the glass tube with the 2nd prefabrication production process of processing the 2nd prefabrication,
With the limit above-mentioned the 2nd prefabrication is heated, the limit wire drawing makes above-mentioned translucent glass mother metal layer and above-mentioned glass tube fusion is integrated and make above-mentioned translucent glass mother metal layer become the wire-drawing process of the above-mentioned clad that is made up of clear glass,
In above-mentioned dehydration sintering circuit, above-mentioned processed and sintering processes are carried out simultaneously,
Above-mentioned dehydration sintering circuit the atmosphere gas that contains non-active gas and halogen gas and contain non-active gas and the atmosphere gas of halogen chemical compound gas at least a atmosphere gas under carry out,
Temperature during processing is more than 1250 ℃, below 1350 ℃,
The average density of above-mentioned translucent glass mother metal layer is 1.8g/cm 3More than, 2.15g/cm 3Below.
12. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
Above-mentioned non-active gas is a helium.
13. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
Above-mentioned halogen gas is a chlorine.
14. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
Above-mentioned halogen compound be in chlorine compound and the fluorine compounds at least any.
15. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
In above-mentioned dehydration sintering circuit, the average density of above-mentioned translucent glass mother metal layer is 2.0g/cm 3More than.
16. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
In above-mentioned the 2nd prefabrication production process, when inserting above-mentioned the 1st prefabrication in the above-mentioned glass tube, be that the state of vertical direction carries out to keep above-mentioned glass tube.
17. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
In above-mentioned the 2nd prefabrication production process, when inserting above-mentioned the 1st prefabrication in the above-mentioned glass tube, be that the state of horizontal direction carries out to keep above-mentioned glass tube.
18. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
Between above-mentioned the 2nd prefabrication production process and above-mentioned wire-drawing process, the end heating and melting with the wire-drawing direction side of above-mentioned the 2nd prefabrication makes its being integrally formed state.
19. the optical fiber manufacturing method according to above-mentioned 18 records is characterized in that,
Heating means during as the end of the wire-drawing direction side of above-mentioned the 2nd prefabrication of heating and melting are in advance used the injection and in the electric furnace type of heating any of injection, the flame passes of oxyhydrogen flame.
20. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
In above-mentioned the 2nd prefabrication production process, be inserted in the above-mentioned glass tube before, the wire drawing with above-mentioned glass tube in advance begins the side heating and melting, forms closed state.
21. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
The sealing of above-mentioned glass tube is carried out through above-mentioned glass tube is added thermal cut.
22. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
In above-mentioned wire-drawing process, between major general's above-mentioned translucent glass mother metal layer and above-mentioned glass tube, be set to decompression state.
23. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
It is below the 1ppm that above-mentioned glass tube contains through chemical reaction synthetic quartzy type glass and hydroxyl (OH) content.
24. the optical fiber manufacturing method according to above-mentioned 23 records is characterized in that,
Above-mentioned glass tube contains fluorine.
25. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
Above-mentioned glass tube is 1 glass tube.
26. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
Above-mentioned glass tube is to be a plurality of glass tubes of concentric circles with respect to length direction axle lamination.
27. the optical fiber manufacturing method according to above-mentioned 26 records is characterized in that,
The limit is carried out the wire drawing limit to above-mentioned translucent glass mother metal layer and above-mentioned a plurality of glass tube and is formed fusion when integrated, with all being set to decompression state between above-mentioned translucent glass mother metal layer and the above-mentioned glass tube and between 2 adjacent glass tubes.
28. the optical fiber manufacturing method according to above-mentioned 26 records is characterized in that,
The glass tube that above-mentioned glass tube comprises fluorine-containing glass tube and is made up of pure silica glass, and use the above-mentioned glass tube that constitutes by pure silica glass at outermost layer at least.
29. the optical fiber manufacturing method according to above-mentioned 11 records is characterized in that,
To the direction throw light of above-mentioned optical fiber from reporting to the leadship after accomplishing a task; The forward scattering light from above-mentioned fibre scattering is accepted with image sensor in the place ahead in above-mentioned light working direction; Handle its output with signal processing part; Obtain the scattered light intensity distribution patterns, judge in the above-mentioned optical fiber from this scattered light intensity distribution patterns to have or not bubble.
The simple declaration of accompanying drawing
Fig. 1 is the process flow diagram of order of operation of embodiment 1 that manufacturing approach and the optical fiber manufacturing method of the fibre parent material that the present invention relates to are shown.
Fig. 2 is the figure that the refractive index profile of the optical fiber that embodiment 1 makes is shown.
Fig. 3 is a mode chart of the part of the core soot of the manufacturing process of the core soot (コ ア ス one ト) of explanation employing VAD method being processed vertical section.
Fig. 4 is an outboard profile of the part of the heating furnace of the electric furnace stretching device of the state that the heat drawing plug is shown being processed vertical section.
Fig. 5 is the mode chart that the part of the porous preform layer of the formation of the porous preform layer of explanation employing OVD method is made vertical section.
Fig. 6 is for the porous preform layer being processed the skiagraph of the employed dehydration-sintering furnace of translucent glass mother metal layer in dehydration procedure and sintering circuit.
Fig. 7 is in clear glass chemical industry preface, translucent glass mother metal layer is processed the skiagraph of the employed zone furnace of the 2nd clad.
Fig. 8 is the side view of formation that the summary of defect of optical fiber pick-up unit is shown.
Fig. 9 be illustrate input light transmission longitudinal bodies defect detecting device imageing sensor scattered light and be the key diagram of the scattered light intensity distribution patterns that obtains of basis with this scattered light.
Figure 10 is the curve map of relation of density of obtaining pressure and the translucent glass mother metal layer of the sintering circuit of in transparence, carrying out for not residual bubble through calculating.
Figure 11 is the process flow diagram of order of operation that the embodiment 2 of the optical fiber manufacturing method that the present invention relates to is shown.
Figure 12 is the refractive index profile that the optical fiber of making among the embodiment is shown.
Figure 13 is a mode chart of the part that explanation adopts the OVD method to form the porous matter parent terrain of porous matter parent terrain being processed vertical section.
Figure 14 is a skiagraph of in dehydration procedure and sintering circuit, the tubular porous plastid being processed the employed dehydration-sintering furnace of translucent glass cylinder.
Figure 15 (a) and Figure 15 (b) are the process charts of state that the end fusion sealing translucent glass cylinder end of the wire-drawing direction side through the oxyhydrogen flame heating and melting translucent glass cylinder that from pulverizing jet, ejects is shown.
Figure 16 (a) and Figure 16 (b) are illustrated in to insert before the plug, the process chart of the end of the end fusion sealing translucent glass cylinder of the wire-drawing direction side of heating and melting translucent glass cylinder.
Figure 17 is the process flow diagram of order of embodiment 3 that the manufacturing approach of the light that the present invention relates to is shown.
Figure 18 is the drawing that is illustrated in the refractive index profile of the optical fiber of making among the embodiment 12.
Figure 19 is the drawing that is illustrated in the refractive index profile of the optical fiber of making among the embodiment 13.
Figure 20 is the drawing that is illustrated in the refractive index profile of the optical fiber of making among the embodiment 14.
Figure 21 is the drawing that is illustrated in the refractive index profile of the optical fiber of making among the embodiment 15.
Figure 22 is the drawing that is illustrated in the refractive index profile of the optical fiber of making among the embodiment 16.
Figure 23 processes the skiagraph of the employed dehydration-sintering furnace of translucent glass mother metal layer with the porous preform layer in the dehydration sintering circuit.
Figure 24 is an outboard profile of the part of the state that contains separated foam that translucent glass mother metal layer is shown being processed amplification profile diagram.
Figure 25 processes the outboard profile of section with the sleeve pipe that in the sleeve pipe that remains on vertical direction roughly, inserts the state of the 1st prefabrication is shown.
Figure 26 processes the outboard profile of section with the sleeve pipe that in the sleeve pipe that remains on general horizontal direction, inserts the state of the 1st prefabrication is shown.
Figure 27 (a) and Figure 27 (b) are the process charts of state that the fusion closed casing end, end of the wire-drawing direction side through oxyhydrogen flame heating and melting the 2nd prefabrication that from pulverizing jet, ejects is shown.
Figure 28 (a) and Figure 28 (b) are illustrated in to insert before the 2nd prefabrication process chart of the end of the end fusion closed casing of the wire-drawing direction side of heating and melting sleeve pipe.
Figure 29 is the mode chart that the core soot manufacturing process of the VAD method that adopts embodiment 13 is described.
Figure 30 be illustrate that the explanation porous layer forms operation form the outboard profile of the state of porous layer in the plug periphery.
Figure 31 is the sectional drawing of dehydration-sintering furnace that the state of dehydration sintering circuit is shown.
Figure 32 is the outboard profile that the part of the tapered portion at corresponding mother metal both ends has the dehydration-sintering furnace of special well heater.
Figure 33 is illustrated in the heating furnace figure that leading section that wire drawing with the translucent glass layer begins side carries out the state of clear glassization.
Figure 34 is illustrated in the figure that carries out the state of wire drawing in the fiber drawing furnace.And,
Figure 35 is the drawing that forms the state of front end tapered portion when being illustrated in the heating furnace leading section that wire drawing with the translucent glass layer begins side and carrying out clear glassization through fusing.
Detailed Description Of The Invention
Below, based on accompanying drawing the fibre parent material that the present invention relates to, the manufacturing approach of fibre parent material and the embodiment of optical fiber manufacturing method are described at length.In addition, the present invention does not receive the qualification of these embodiments.Below, the summary of the characteristic on the formation of the present invention is described as embodiment, will specify as embodiment according to practical substances afterwards.
Optical fiber manufacturing method of the present invention is applied to have sandwich layer and clad and has in the optical fiber manufacturing method of various index distribution characteristics, is useful, particularly, is fit to single-mode fiber (Single Mode Fiber; Below be called SMF) etc. optical fiber manufacturing method.In addition, also go for transmitting loss and be suitable for the methods for optical fiber manufacture that broadband WDM transmits for a short time.
[embodiment 1]
Fig. 1 is the process flow diagram of order of operation of embodiment 1 that manufacturing approach and the optical fiber manufacturing method of the fibre parent material that the present invention relates to are shown.The manufacturing approach of the fibre parent material of this embodiment comprises the porous preform layer and forms operation and dehydration procedure and sintering circuit and clear glass chemical industry preface.In addition, the optical fiber manufacturing method of this embodiment has the wire-drawing process of the clear glass chemical industry preface that replaces the fibre parent material manufacturing approach.
At first, form in the operation at the porous preform layer of step S1, the quartzy type glass granules of periphery deposit that on central shaft, has sandwich layer 3A and be the bar-shaped plug 7A that comprises quartzy type glass forms porous preform layer 9C.
Then; In the dehydration procedure of step S2, under the decompression of regulation, in the atmosphere of non-active gas and halogen gas or in the atmosphere of non-active gas and halogen chemical compound gas, under any one environment (condition) in 3 kinds of environment (condition) porous preform layer 9C dewatered.
Have, in the sintering circuit of step S3, the porous preform layer 9C of the above-mentioned dehydration procedure of sintering dehydration under reduced pressure changes the translucent glass mother metal layer 9B of the translucent glass state that contains the separated foam that is essentially vacuum into again.Here, so-called " translucent glass state " is meant and all contains the state of separated foam, gonorrhoea and opaque state in appearance basically equably.In contrast, so-called " clear glass state " is meant that all states that does not contain separated foam basically equably are transparent state in appearance the separated foam that removes the pettiness in the part that a part remains in defective mode.In addition, here, so-called " separated foam " is meant bubble or the space that forms in the inside of translucent glass mother metal layer 9B and physically isolate with atmosphere gas on every side.Have, here, so-called " vacuum " is meant the following definition among the JIS Z 8126 again, that is, and and " the specific spatiality that is full of with the gas of the pressure that forces down than atmosphere ".
And; In the manufacturing approach of the fibre parent material in this embodiment; Next carry out the transition to the clear glass chemical industry preface of step S4, the translucent glass mother metal layer 9B that in non-active gas (except the helium) atmosphere, will contain separated foam carries out clear glass formation clad 9A.Make fibre parent material thus.
In addition, in the optical fiber manufacturing method of this embodiment, do not carry out step S4, can carry out the transition to the wire-drawing process of step S5 yet.And, in this wire-drawing process, make translucent glass mother metal layer 9B wire drawing become transparent glass layer.
According to manufacturing approach and methods for optical fiber manufacture by the fibre parent material of such order; Can not use expensive helium, can make large-scale fibre parent material in the short time, in addition; Owing to also can make the manufacturing equipment long lifetime and omit operation, therefore can reduce the optical fiber manufacturing cost.
Below, with embodiment detailed embodiment is described.In addition, degree no problem on understanding content is recorded and narrated drawing, and its shape is not necessarily dwindling according to reality.In addition, in the present embodiment, the short of special instruction of all characteristics of optical fiber, then be with ITU-T G.650 in regulation be defined as benchmark.
(embodiment 1)
Fig. 2 illustrates the figure that the fibre parent material that embodiment 1 is made is finally processed the refractive index profile of optical fiber.As shown in Figure 2, because optical fiber has the index distribution of ladder refractive index type, therefore have the diffusing wavelength of zero in 1.3 μ m band territory, be so-called SMF.In Fig. 2, optical fiber becomes the rhythmo structure that forms the section concentric circles, form sandwich layer 3A along central axis, and afterwards, radius vector is to extroversion from central division, and each layer that is formed by the order according to the 1st clad 5A and the 2nd clad 9A constitutes.
The part that constitutes by sandwich layer 3A and the 1st clad 5A be with after the corresponding part of plug 7A stated.If only the part of plug 7A is observed, the external diameter of sandwich layer 3A and the 1st clad 5A is 4.8/1 than (below be called coating/core than).In addition, in the present embodiment, the external diameter of so-called sandwich layer 3A is meant the diameter with respect to peaked 1/2 part of the specific refractivity difference of the sandwich layer 3A of the refractive index of the 1st clad 5A.
The making of plug
In the present embodiment, at first make the core soot 7B that the back becomes plug 7A with the VAD legal system.Fig. 3 is the mode chart of manufacturing process of the core soot 7B of the explanation VAD method that adopts present embodiment, with the part of core soot 7B as skiagraph.In Fig. 3, in the VAD method,, send into silicon tetrachloride (SiCl by gasification through comprising the core pulverizing jet 21 of multiple tubular construction 4), germanium tetrachloride (GeCl 4), oxygen (O 2) and hydrogen (H 2) gas 23 that constitutes, and ignition.And the reaction that in flame, is hydrolyzed obtains the synthetic glass particulate.Spray this synthetic glass particulate to kind of rod 11, and be attached on kind of the rod 11.
The synthetic glass particulate that injection is adhered to forms sandwich layer soot 3B.Sandwich layer soot 3B is the part that became sandwich layer 3A afterwards.And, plant excellent 11 and pull out to the last direction of Fig. 3 lentamente while rotating.
On the top of core pulverizing jet 21 similar coating pulverizing jet 22 is set, sends into silicon tetrachloride (SiCl 4), oxygen (O 2) and hydrogen (H 2) gas 24 that constitutes, and reaction forms the clad soot 5B that became the 1st clad 5A afterwards in the periphery of core soot 7B.Thus, become the bar-shaped core soot 7B of the formation regulation thickness that contains sandwich layer soot 3B and clad soot 5B.
Then, this core soot 7B is carried out processed and sintering processes.This processing is identical with in the past, does not have special characteristic, so drawing omits.Through this dehydration sintering processes, core soot 7B is become the plug 7A that contains sandwich layer 3A and the 1st clad 5A by clear glassization.
The stretching of plug
Then, should be processed the rod of external diameter 51mm by the plug 7A that contains sandwich layer 3A and the 1st clad 5A of clear glassization with vertical electric furnace stretching device 41 heat drawing shown in Figure 4.Fig. 4 is the outboard profile of electric furnace stretching device 41 that the state of heat drawing plug 7A is shown, and the part of heating furnace 42 is made vertical section.In Fig. 4, electric furnace stretching device 41 has: have the heating furnace 42 of the opening 42a that connects vertical direction, 42b and be arranged on the top handle part 43 of these heating furnace 42 tops and be arranged on the bottom handle part 44 of heating furnace 42 belows.
Heating furnace 42 inside have the well heater cylindraceous 45 as heater.Plug 7A extends ground according to the central axis along well heater 45 with vertical direction upper and lower end parts pass through openings 42a, 42b, and the outside of stretching out heating furnace 42 is installed.And the upper end of plug 7A is fixing with the top clamp that is arranged on top handle part 43 46, and on the other hand, the bottom of plug 7A is fixing with the bottom clamp that is arranged on bottom handle part 44 47.By guide rail 48 and guide rail 49 guiding, support can be moved at the length direction of plug 7A respectively for top handle part 43 and bottom handle part 44.
The action of stretching device 41 is described.The limit is with the large diameter part of well heater 45 heating plug 7A, the limit with top clamp 46 to moving relative to approaching direction for heating furnace 42, the bottom clamp to for heating furnace 42 relative to away from direction move, thus, plug 7A is stretched as the rugosity of regulation.
In addition, the thermal source in this heat drawing operation is not limited only to heating furnace 42, also can use flames such as oxyhydrogen flame or plasma flame etc.
The porous preform layer forms operation
Then, with the quartzy type glass granules of OVD method deposit, make the porous preform layer 9C of diameter 300mm in the periphery of the plug 7A that has stretched.Porous preform layer 9C is the 9B that became translucent glass mother metal layer afterwards, and finally to be changed into by clear glass be the part of the 2nd clad 9A.
Fig. 5 is that explanation adopts the OVD legal system to make the mode chart of porous preform layer 9C, with the part of porous preform layer 9C as vertical section.In Fig. 5, in the OVD method,, send into the silicon tetrachloride (SiCl of gasification through pulverizing jet 31 4), oxygen (O 2) and hydrogen (H 2) gas 32 that constitutes, ignition.And hydrolysis reaction in flame obtains the synthetic glass particulate.This synthetic glass particulate is injected on the plug 7A of rotation, be deposited on plug 7A around.The thickness of the layer of the synthetic glass particulate of a deposit is very not thick, so the limit comes and goes pulverizing jet 31 repeatedly, the limit repeatedly its up to the porous preform layer 9C that becomes abundant rugosity.
The average density of porous preform layer 9C (that is, will use from cumulative volume from the weight of porous preform layer 9C that general assembly (TW) deducts the weight of plug 7A deduct the value that the volume of porous preform layer 9C of the volume of plug 7A removes) is about 0.7g/cm 3
Dehydration procedure and sintering circuit
Then, with dehydration-sintering furnace shown in Figure 6 61, under the condition of table 1,, process the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside with this porous preform layer 9C dehydration sintering.
(table 1) dehydration conditions
Figure GSB00000639905400141
Sintering condition
Project Condition
Sintering temperature 1400℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In Fig. 6; Dehydration-sintering furnace 61 has: as quartz glass system can be airtight container quartzy stove core barrel 62 and be arranged on a plurality of well heaters of ring-type (マ Le チ ヒ one タ) 63 of a plurality of heaters of conduct around this quartz stove core barrel 62 and the time with quartzy stove core barrel 62 and well heater 63 all coatings, form body of heater 67 and the thermal insulation material 66 of between quartzy stove core barrel 62 and a plurality of well heater 63 and body of heater 67, filling of the shell of dehydration-sintering furnace 61.
In the inside of quartzy stove core barrel 62, be provided with the plug 7A that periphery has porous preform layer 9C.In dehydration procedure, import chlorine (Cl to quartzy stove core barrel 62 inside according to the never illustrated gas introduction port of the flow of the regulation shown in the table 1 2) and nitrogen (N 2), simultaneously, never illustrated gas discharge outlet is discharged an amount of gas, thus, keeps the value of pressure for stipulating in the quartzy stove core barrel 62.Vacuum pump 65 is connected in quartzy stove core barrel 62, in sintering circuit, uses this vacuum pump with inner pressure relief.Porous preform layer 9C carries out processed and sintering processes and becomes the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside in quartzy stove core barrel 62 inside.
In the stage of processed and sintering processes end, translucent glass mother metal layer 9B becomes the state that contains the separated foam of physically isolating with the ambient gas atmosphere.In the present embodiment, with this state as " translucent glass state ".Should " translucent glass state " be the separated foam that all contains the bubble that conduct and ambient gas atmosphere physically isolate basically equably, gonorrhoea and opaque state in appearance.In addition, smooth surface and have gloss.In addition, the density of the translucent glass mother metal layer 9B of this moment is the density (2.2g/cm that finally becomes the 2nd clad 9A of transparent fully glass 3) 95%, that is, and 2.09g/cm 3
In the method in the past of the porous preform layer being processed transparent fully material, at first after the temperature below 1200 ℃ or 1200 ℃ that sintering does not carry out heats next time and fully dewaters, be exposed to and carry out transparence under the hot conditions.That is, carry out transparence through the operation in 2 stages.And, as method in the past, need expensive helium.And, height such as the energy cost of heating and the carrying cost of equipment.
Therefore, in the present embodiment, import and to realize under reduced pressure that after processed the temperature range of semi-sintered condition degree carries out the method for sintering.In the sintering process of glass porous plastid, increase the combination between particulate through heating, pore reduces, and increase in density transforms to the clear glass that does not finally contain bubble.
Sintering carry out speed dependent in conditions such as the particle diameter of temperature and time, glass granules or compositions and change, but porous plastid surface person sintering carries out easily.The result of the sintered porous matter mother metal layer 9C of dehydration finds under all temps, heat time heating time, has in fact and the state of the separated foam of atmosphere gas barrier on every side if porous preform layer 9C becomes, as long as average density is 1.8g/cm 3Or 1.8g/cm 3More than, preferred 2.0g/cm 3Or g/cm 3More than get final product.
In addition, from the viewpoint that bubble is residual that prevents after this clear glass chemical industry preface or wire-drawing process, there is the upper limit for the pressure of the sintering circuit of under reduced pressure carrying out.In order to see through quartz glass in clear glass chemical industry preface or the wire-drawing process below of the residual gas in the separated foam not as bubble and residual, the total amount of the residual gas in the separated foam is for the saturation solubility in the quartz glass under the transparence temperature or be necessary below the saturation solubility.For example, residual gas is nitrogen (N 2) time, the N in the quartz glass 2Solubleness S under atmosphere gas temperature T representes with following formula according to document " G.C.Beerkens, Advances in the fusion and processing of glass 2nd, 1990vol63k, pp222-242 "
S[cc(STP)/cm 3*atm]＝0.0252×EXP(-6665/T) (1)
Here, STP is meant standard temperature, normal pressure.
Figure 10 illustrates through calculating, the N in separated foam under the decompression 2As residual situation, by the N under T=1600 ℃ of the atmosphere gas temperature 2Quartz glass in saturation solubility 7.18 * 10 -4[cc (STP)/cm 3* atm], be the transparence and the curve map of the relation of the density of pressure and the translucent base glass material layer of the sintering circuit of residual bubble not.
The density of translucent glass mother metal layer is ρ 1 [g/cm 3] time, the volume of the separated foam that translucent glass mother metal layer is contained is expressed as (1-ρ 1/2.2) [cc/cm 3].Because the sintering atmosphere gas of residual decompression in the separated foam, when sintering pressure was P (Pa), the gas volume in the separated foam was:
(1-ρ 1/2.2) * P/ (1.013 * 105) [cc/cm 3] (1.013 * 105 is atmospheric pressure).Gas volume in this separated foam if saturation solubility in the quartz glass under the transparence temperature or saturation solubility with next can transparence, therefore, be necessary sintering is proceeded to
(saturation solubility)＞(1-ρ 1/2.2) * P/ (1.013 * 105)＞0 (2).
The curve of Figure 10 is to be depicted as
7.18×10 -4＝(1-ρ1/2.2)×P/(1.013×105)
The curve map of relation of density of translucent glass mother metal layer of sintering circuit and pressure, (2) formula is represented the zone of representing with oblique line that the curve of Figure 10 is above.
In addition, experimental result under various conditions shows, becomes 2.13g/cm in the density of translucent glass mother metal layer 3Or 2.13g/cm 3In the above moment, all bubble all becomes separated foam.Therefore, under the pressure that 2000Pa is higher in than Figure 10, satisfy (2) formula ground and form very difficulty of translucent glass mother metal layer, do not have also difficulty of residual bubble ground transparence.
In addition, for the bubble of doing one's utmost to reduce in clear glass chemical industry preface or wire-drawing process residual, the preferred especially 1000Pa of the pressure in the sintering circuit or below the 1000Pa.
Clear glass chemical industry preface
Then, in nitrogen environment, plug 7A and translucent glass mother metal layer 9B are heat-treated, process the 2nd clad 9A of diameter 170mm with zone furnace shown in Figure 7 71.The heat-treat condition of this moment is shown in table 2.
(table 2)
Project Condition
Heter temperature 1600℃
The drop-down speed of mother metal 100mm/ hour
The mother metal revolution 10 rev/mins
Gaseous species and flow 10 liters/minute in nitrogen
In Fig. 7, zone furnace 71 has quartzy stove core barrel 72 and is arranged on this quartz stove core barrel 72 ring-shaped heater 73 as heater on every side.In quartzy stove core barrel 72 inside, support plug 7A and translucent glass mother metal layer 9B to move at length direction.Import nitrogen (N with the never illustrated gas introduction port of the flow of the regulation shown in the table 2 to quartzy stove core barrel 72 inside 2), simultaneously, never illustrated escape hole is discharged an amount of gas, keeps the value of pressure for stipulating in the quartzy stove core barrel 72 thus.
The action of declare area heating furnace 71.Plug 7A and translucent glass mother metal layer 9B move at length direction, change the relative position for well heater 73.And; With the partially transparent vitrifacation of well heater 73 heating, in the present embodiment, at first the bottom of translucent glass mother metal layer 9B is by clear glassization; Be accompanied by translucent glass mother metal layer 9B and move according to the direction of arrow among the figure, upper direction carry out clear glassization successively.Make fibre parent material like this.
(embodiment 2)
To use and embodiment 1 same dehydration-sintering furnace shown in Figure 6 61 sintering that under the condition of table 3, dewaters with plug 7A that makes with the same method of embodiment 1 and porous preform layer 9C, process the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside.
In the present embodiment, in dehydration procedure also with quartzy stove core barrel 72 inner pressure relieves.
(table 3) dehydration conditions
Project Condition
Dehydration temperaturre 1100℃
Dewatering time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
Sintering condition
Project Condition
Sintering temperature 1400℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of porous preform layer 9C is 2.1g/cm 3, be the density (2.2g/cm of the base glass material of complete transparence 3) 95%.
Then, with plug 7A and translucent glass mother metal layer 9B use with the same zone furnace shown in Figure 7 71 of embodiment 1 through heat-treating with the condition shown in the same table 2 of embodiment 1, make the fibre parent material of diameter 170mm.
(embodiment 3)
To use and embodiment 1 same dehydration-sintering furnace shown in Figure 6 61 sintering that under the condition of table 4, dewaters with plug 7A that makes with the same method of embodiment 1 and porous preform layer 9C, process the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside.
In the present embodiment, in dehydration procedure also with quartzy stove core barrel 72 inner pressure relieves.
(table 4) dehydration conditions
Project Condition
Dehydration temperaturre 1100℃
Dewatering time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
Sintering condition
Project Condition
Sintering temperature 1350℃
Programming rate 2 ℃/minute
The sintering temperature retention time 4 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of porous preform layer 9C is 2.0g/cm 3, be the density (2.2g/cm of the base glass material of complete transparence 3) 91%.
Then, with plug 7A and translucent glass mother metal layer 9B use with the same zone furnace shown in Figure 7 71 of embodiment 1 through heat-treating with the condition shown in the same table 2 of embodiment 1, make the fibre parent material of diameter 170mm.
(embodiment 4)
To use and embodiment 1 same dehydration-sintering furnace shown in Figure 6 61 sintering that under the condition of table 5, dewaters with plug 7A that makes with the same method of embodiment 1 and porous preform layer 9C, process the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside.
In the present embodiment, only in sintering circuit with quartzy stove core barrel 72 inner pressure relieves.
(table 5) dehydration conditions
Figure GSB00000639905400181
Sintering condition
Project Condition
Sintering temperature 1350℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of porous preform layer 9C is 1.8g/cm 3, be the density (2.2g/cm of the base glass material of complete transparence 3) 82%.
Then, with plug 7A and translucent glass mother metal layer 9B use with the same zone furnace shown in Figure 7 71 of embodiment 1 through heat-treating with the condition shown in the same table 2 of embodiment 1, make the fibre parent material of diameter 170mm.
(embodiment 5)
To use and embodiment 1 same dehydration-sintering furnace shown in Figure 6 61 sintering that under the condition of table 6, dewaters with plug 7A that makes with the same method of embodiment 1 and porous preform layer 9C, process the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside.
In the present embodiment, only in sintering circuit with quartzy stove core barrel 72 inner pressure relieves.
(table 6) dehydration conditions
Figure GSB00000639905400191
Sintering condition
Project Condition
Sintering temperature 1400℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of porous preform layer 9C is 2.1g/cm 3, be the density (2.2g/cm of the base glass material of complete transparence 3) 95%.
This translucent glass mother metal layer 9B (diameter 174mm) be clear glassization not, directly carries out wire drawing.
(comparative example 1)
To use and embodiment 1 same dehydration-sintering furnace shown in Figure 6 61 sintering that under the condition of table 7, dewaters with plug 7A that makes with the same method of embodiment 1 and porous preform layer 9C, process the translucent glass mother metal layer 9B that separated foam is contained in inside.In this comparative example, in the dehydration procedure sintering circuit do not reduce pressure in quartzy stove core barrel 72 inside.In addition, in sintering circuit, use helium as non-active gas.
(table 7) dehydration conditions
Figure GSB00000639905400201
Sintering condition
In this stage, the average density of porous preform layer 9C is 2.1g/cm 3, be the density (2.2g/cm of the base glass material of complete transparence 3) 95%.
Then, with plug 7A and translucent glass mother metal layer 9B use with the same zone furnace shown in Figure 7 71 of embodiment 1 through heat-treating with the condition shown in the same table 2 of embodiment 1, make the fibre parent material of diameter 170mm.
Wire-drawing process
Then, the fibre parent material of embodiment 1～4 and comparative example 1 making and the plug 7A and the translucent glass mother metal layer 9B of embodiment 5 making are carried out wire drawing.During wire drawing, at 2 layers of UV gel-type resin of glass optical fiber outside coating, irradiation ultraviolet radiation, make resin solidification after, be wound on the spool through the coiling capstan winch.In addition, with the inboard of coating become main stor(e)y, the outside is called sublevel,, sublevel the earth little according to the Young modulus main stor(e)y of these layer selected material.Drawing speed in the present embodiment is made as the 2000m/ branch.
To with the various SMF that make among above-mentioned each embodiment, measure bad incidence and the transmission characteristic of bubble in the wire drawing.Its result is shown in table 8, table 9.
In addition, confirm the not residual situation that is present in the separated foam of translucent glass mother metal layer 9B in the glass optical fiber in the wire-drawing process with the optical fiber defect detecting device.
Particularly; For the glass optical fiber in the wire-drawing process the axle from light such as transverse direction illuminating laser beams; Accept forward scattering light through imageing sensor from this glass optical fiber; Unusually detect cavity blemish such as bubble through what detect its scattered intensity part pattern, keep watch on the bubble in the glass optical fiber.
In addition, the defect of optical fiber pick-up unit inspection below the bad incidence of the bubble in the wire drawing is used.Fig. 8 is the side view of formation that the summary of defect of optical fiber pick-up unit is shown.In addition, Fig. 9 be illustrate input light transmission longitudinal bodies defect detecting device shown in Figure 8 imageing sensor scattered light and be the key diagram of the scattered light intensity distribution patterns that obtains of basis with this scattered light.This defect of optical fiber pick-up unit is following structure: as shown in Figure 8, from the fibre parent material to the wire drawing after, with uncoated state; Continuously to operating glass optical fiber 51 irradiation light 83, accepted with imageing sensor 85 by light its forward scattering light linear sensor of 84 usefulness CCD or photodiode array etc. from laterally, its output is handled with signal processing part 86; Judge the scattered light intensity distribution patterns that obtains from this signal processing part 86 with detection unit 87; Simultaneously, the result of handling part 86 is shown with supervision portion 88, if be judged as unusual; Then give the alarm from warning portion 89, with result of determination with recording portion 90 records.
(table 8)
Bubble fraction defective (l/km)
Embodiment 1; SMF (1) 0.001
Embodiment 2; SMF (2) 0.001
Embodiment 3; SMF (3) 0.001
Embodiment 4; SMF (4) 0.002
Embodiment 5; SMF (5) 0.002
Comparative example 1; SMF (6) 0.01
Learn that like table 8,9 any one cutoff wavelength λ cc of each optical fiber of embodiment 1 to 5 in 1310nm or the wavelength region may more than the 1310nm, can guarantee single mode operation all at 1310nm or below the 1310nm.
In addition, said here cutoff wavelength is the cable cut-off wavelength λ cc that G.650 defines in the standard at ITU-T.
In addition, any one loss at 1385nm in the optical fiber of embodiment 1 to 5 is 0.40dB/km or below the 0.40dB/km, becomes the abundant little optical fiber of absorption loss of hydroxyl (OH).
In addition, the tension force that is equivalent to for the length growth rate of the total length of the optical fiber after the wire drawing about 2% is given on the limit, and Bian Yijuan tests the intensity of each optical fiber to other spools.Its result can confirm can not cause fracture, is no problem optical fiber.
As stated, the optical fiber of present embodiment is on the surface of translucent glass mother metal layer 9B or open pore is arranged, or has when concavo-convex, can not cause special worry owing to the problems such as strength deterioration that cause from sneaking into of the polluter in the heating furnace.That is, this be because, translucent glass mother metal layer 9B is sintered to bubble or the concavo-convex degree that the opening of polluter is not introduced on its surface, promptly being sintered to inner bubble becomes separated foam.
On the other hand, the dehydration sintering circuit atmosphere gas of porous preform layer 9C is not set to decompression state, and in sintering circuit, has used in the comparative example 1 (SMF (6)) of helium, though transmission characteristic is no problem, the bubble fraction defective is high.Infer this be because; In the contained separated foam of translucent glass mother metal layer 9B; During residual dehydration sintering as the helium of atmosphere gas; When transparence is handled, see through helium to the glass and can not break away from fully to continue to dissolve and stay to glass outer, its in wire drawing, foam in optical fiber, form empty.
(embodiment 6)
In above-mentioned each embodiment, also can add fluorine to clad.In the present embodiment, in the time of will dewatering sintering with embodiment 1 same plug 7A that makes and porous preform layer 9C, add fluorine, process the translucent glass mother metal layer 9B that the separated foam that is essentially vacuum is contained in inside with the condition of table 10.
(table 10) dehydration conditions
The fluorine adding conditional
Figure GSB00000639905400241
Sintering condition
Project Condition
Sintering temperature 1350℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of porous preform layer 9C is 2.1g/cm 3, be the density (2.2g/cm of the base glass material of complete transparence 3) 95%.
Then, the product of the translucent glass mother metal layer 9B that forms semi-sintered condition around the plug 7A is heat-treated by the condition shown in the table 2 with the heating furnace of other regional type of heating, process the transparent optical fibers mother metal of diameter 170mm.The refractive index low 0.4% of the pure quartzy type glass of refractive index ratio of the clad of interpolation fluorine.Below, carry out the order same with other embodiment, in wire drawing, implement to coat, obtain the optical fiber that not residual bubble in the optical fiber after wire drawing, coating external diameter that intensity is also no problem are about 250 μ m.
Like present embodiment, also the little zone of refractive index can be set in the part of clad.
According to the present invention; The periphery deposited glass particulate that has sandwich layer and be bar-shaped plug forms the porous preform layer; Under reduced pressure, under any one the condition under the atmosphere of atmosphere, non-active gas and the halogen chemical compound gas of non-active gas and halogen gas with above-mentioned porous preform pull-up water, the above-mentioned porous preform layer sintering after under reduced pressure will dewatering reaches becomes the translucent glass mother metal layer that contains separated foam, in non-active gas (except the helium) atmosphere, will contain the above-mentioned translucent glass mother metal layer transparence of separated foam and becomes clad; Therefore; Do not use expensive helium, can make large-scale fibre parent material in the short time, in addition; Owing to also can make the manufacturing equipment long lifetime and omit operation, therefore can reduce the optical fiber manufacturing cost.
[embodiment 2]
Figure 11 is the process flow diagram of order of operation that the embodiment 2 of the optical fiber manufacturing method that the present invention relates to is shown.The methods for optical fiber manufacture of this embodiment comprises: tubular porous plastid production process (step S101) and dehydration procedure (step S102) and sintering circuit (step S103) and plug insert operation (step S104) and wire-drawing process (step S105).
In tubular porous plastid production process, form porous preform layer 109D at the quartzy type glass granules of the periphery deposit of mandrel 153, from above-mentioned porous preform layer 109D, extract mandrel 153 109C of manufacturing barrel-shaped porous plastid out then.
In ensuing dehydration procedure; Under the decompression of regulation or under the atmosphere of nonactive body and halogen gas or under any one environment (condition) of the 3 kinds of environment (condition) under the atmosphere of non-active gas and halogen chemical compound gas, with above-mentioned tubular porous plastid 109C dehydration.
Have again, in the sintering circuit below, with the tubular porous plastid 109C of dehydration under reduced pressure sintering reach and become the translucent glass cylinder of the translucent glass state that contains the separated foam that is essentially vacuum 109B.
Insert in the operation at ensuing plug, will have sandwich layer 103A and be bar-shaped plug 107A and insert among the translucent glass cylinder 109B.
Have again; In ensuing wire-drawing process; The limit is to having inserted the translucent glass cylinder 109B heating of plug 107A, and the clad 109A that the limit makes plug 107A and translucent glass cylinder 109B fusion is integrated and semi-transparent circle cylindrical shell 109B wire drawing is become is made up of clear glass makes optical fiber 151.
As long as the methods for optical fiber manufacture of the such operation of employing just can not use expensive helium, and makes large-scale fibre parent material in the short time, go back because the long lifetime of manufacturing equipment also can be simplified working process, so can cut down the manufacturing cost of optical fiber.
Below, with embodiment detailed embodiment is described.In addition, degree no problem on understanding content is recorded and narrated drawing, and its formation is not necessarily dwindling according to reality.In addition, in the present embodiment, the short of special instruction of all characteristics of optical fiber, then be with ITU-T G.650 in regulation be defined as benchmark.
(embodiment 7)
Figure 12 is the drawing that optical fiber 151 refractive index profiles of embodiment 7 making are shown.As shown in Figure 2, because optical fiber 151 has the index distribution of ladder refractive index type, therefore have the diffusing wavelength of zero in 1.3 μ m band territory, be so-called SMF.In Figure 12, optical fiber 151 becomes the rhythmo structure that forms the section concentric circles, form sandwich layer 103A along central axis, and afterwards, radius vector is to extroversion from central division, and each layer that is formed by the order according to the 1st clad 105A and the 2nd clad 109A constitutes.In addition, the clad of implementing in the outside of the 2nd clad 109A omits.
The part that constitutes by sandwich layer 103A and the 1st clad 105A be with after the corresponding part of plug 107A stated.If only the part of plug 107A is observed, the external diameter of sandwich layer 103A and the 1st clad 105A is 3.4/1 than (below be called coating/core than).In addition, in the present embodiment, the external diameter of so-called sandwich layer 103A is meant the diameter with respect to peaked 1/2 part of the specific refractivity difference of the sandwich layer 103A of the refractive index of the 1st clad 105A.
The making of plug
In the present embodiment, at first use the method same, promptly became the core soot 107B of plug 107A afterwards with VAD method making shown in Figure 3 with embodiment 1.
Then, this core soot 107B is carried out processed and sintering processes.This is handled with same in the past, does not have special characteristic, so drawing omits.Through this processed sintering processes, core soot 107B is become the plug 107A that contains sandwich layer 103A and the 1st clad 105A by clear glassization.
The stretching of plug
Then, with this by the plug 107A that contains sandwich layer 103A and the 1st clad 105A of clear glassization with vertical electric furnace stretching device 41 heat drawing shown in Figure 4, process the rod of external diameter 35mm.
In addition, the thermal source in this operation is not limited only to heating furnace 42, also can use flames such as oxyhydrogen flame or plasma flame etc.When having hydroxyl (OH) pollution problems, not preferred usually oxyhydrogen flame, and preferably use electric furnace or plasma flame.But, if coating/core ratio is about 4 times, even oxyhydrogen flame does not have special problem yet.
Tubular porous plastid production process
In quartzy type of glass handle (Ha Application De Le) 155 of tubulose; The diameter that insertion is made by high-purity alpha-alumina or high purity carbon is the mandrel 153 of 36mm; In the periphery of mandrel 153,, make the tubular porous plastid 109C of external diameter 300mm with the quartzy type glass granules of OVD method deposit shown in Figure 13.Tubular porous plastid 109C became translucent glass cylinder 109B afterwards, so that finally become the part of the 2nd clad 109A by well-illuminated vitrifacation.
Figure 13 is that explanation adopts the OVD method to form the mode chart of porous preform layer 109D, with the part of porous preform layer 109D as vertical section.In Figure 13, in the OVD method,, send into the silicon tetrachloride (SiCl of gasification through pulverizing jet 131 4), oxygen (O 2) and hydrogen (H 2) gas 132 that constitutes, ignition.And hydrolysis reaction in flame obtains the synthetic glass particulate.This synthetic glass particulate is injected on the mandrel 153 of rotation, be deposited on mandrel 153 around.The thickness of the layer of the synthetic glass particulate of a deposit is very not thick, so the limit comes and goes pulverizing jet 131 repeatedly, the limit repeatedly its up to the porous preform layer 109D that becomes abundant rugosity.
The average density of porous preform layer 109D (that is, will deduct the value that the value of the volume of mandrel 153 is removed with the weight of porous plastid from cumulative volume) is about 0.7g/cm 3From the porous preform layer 109D that forms the regulation rugosity, extract mandrel 153 out, be produced on the tubular porous plastid 109C that forms through hole on the central shaft.
Dehydration procedure and sintering circuit
Then, with dehydration-sintering furnace shown in Figure 14 161, under the condition of table 11,, process the translucent glass cylinder 109B that the separated foam that is essentially vacuum is contained in inside with this tubular porous plastid 109C dehydration sintering.
(table 11) dehydration conditions
Sintering condition
Project Condition
Sintering temperature 1400℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In Figure 14; Dehydration-sintering furnace 161 has: as quartz glass system can be airtight container quartzy stove core barrel 162 and when being arranged on a plurality of around this quartz stove core barrel 162 as the ring-shaped heater 163 of heater with quartzy stove core barrel 162 and well heater 163 all coatings, form body of heater 167 and the thermal insulation material 166 of between quartzy stove core barrel 162 and well heater 163 and body of heater 167, filling of the case surface of dehydration-sintering furnace 161.
In the inside of quartzy stove core barrel 162, be provided with tubular porous plastid 109C.Through being connected the gas introduction tube 168 on the handle 155 of supporting tubular porous plastid 109C, import by chlorine (Cl 2) and nitrogen (N 2) gas 134 formed, simultaneously, never illustrated gas discharge outlet is discharged an amount of gas, thus, keeps the pressure in the quartzy stove core barrel 162 to be the value of regulation.Vacuum pump 165 is connected in quartzy stove core barrel 162, in sintering circuit, uses this vacuum pump with inner pressure relief.Tubular porous plastid 109C carries out processed in quartzy stove core barrel 162 inside and sintering processes becomes the translucent glass cylinder 109B that the separated foam that is essentially vacuum is contained in inside.
In the stage of processed and sintering processes end, translucent glass cylinder 109B becomes the state that contains the separated foam of physically isolating with the ambient gas atmosphere.In the present embodiment, with this state as " translucent glass state ".Should " translucent glass state " be the separated foam that all contains the bubble that conduct and ambient gas atmosphere physically isolate basically equably, gonorrhoea and opaque state in appearance.In addition, smooth surface and have gloss.In addition, the density of the translucent glass cylinder 109B of this moment is the 2nd clad 109A density (2.2g/cm that finally becomes complete clear glass 3) 95%, that is, and 2.09g/cm 3
In the method in the past of porous plastid being processed transparent fully material, at first after once heating abundant dehydration under the temperature below 1200 ℃ or 1200 ℃ that sintering does not carry out, be exposed to and carry out transparence under the hot conditions.That is, carry out transparence through the operation in 2 stages.And, as this method in the past, need expensive helium.And, height such as the energy cost of heating and the carrying cost of equipment.
Therefore, in the present embodiment, import and to realize under reduced pressure that after processed the temperature range of semi-sintered condition degree carries out the method for sintering.In the sintering process of glass porous plastid, increase the combination between particulate through heating, pore reduces, and increase in density transforms to the clear glass that does not finally contain bubble.
Sintering carry out speed dependent in the particle diameter of temperature and time, particulate or composition and change, but porous plastid surface person carries out sintering easily.And the result of the sintered porous plastid of dehydration shows under all temps, heat time heating time, has in fact and the state of the separated foam of atmosphere gas barrier on every side if the porous preform zone becomes, as long as average density is 1.8g/cm 3Or 1.8g/cm 3More than, preferred 2.0g/cm 3Or 2.0g/cm 3More than get final product.
Plug inserts operation
Then, above-mentioned plug 107A is inserted among the translucent glass cylinder 109B.After inserting end; Shown in figure 15; Oxyhydrogen flame through ejecting from pulverizing jet 135 seals the end heating and melting and the fusion of the wire-drawing direction side of translucent glass cylinder 109B, and simultaneously, the end of clear glass cylinder 109B and the end of plug 107A are melted integrated.The purpose of carrying out this processing is; When in fiber drawing furnace, carrying out the fusion sealing of translucent glass cylinder 109B; Translucent glass cylinder 109B might sneak into contained impurity in the atmosphere gas in this fiber drawing furnace; Pollute the surface of inner face and the translucent glass cylinder 109B of plug 107A thus, therefore, before the fiber drawing furnace of packing into, carry out the fusion sealing of translucent glass cylinder 109B.In addition, integrated if the end of the end of transparence glass cylinder body 109B and plug 107A is melted, can shorten when wire drawing begins to the time that transits to steady state (SS).
In addition; Heating means when carrying out heating and melting in advance as the wire-drawing direction side end of translucent glass cylinder 109B; In the present embodiment; Carrying out the injection of oxyhydrogen flame, but be not limited thereto, also can be injection or the electric furnace heating etc. of injection, the flame passes of inflammable gas flames such as methane.
In addition, insert plug 107A after, end that also can not fusion sealing translucent glass cylinder 109B, but shown in figure 16 adds thermal cut through the end with the wire-drawing direction side of translucent glass cylinder 109B in advance and comes the fusion sealing before insertion.Thus, can prevent the pollution of impurity equally with method shown in Figure 15.In addition, shown in figure 16 when fusing translucent glass cylinder 109B,, in the end of translucent glass cylinder 109B, the limit applies the tractive force shown in black arrow, and the limit adds thermal cut through the oxyhydrogen flame that ejects from pulverizing jet 135.
(embodiment 8)
The sintering that will under the condition of table 12, dewater with the tubular porous plastid 109C of the tubular of perforate on the same central shafts of making of embodiment 7 is processed the translucent glass cylinder 109B that the separated foam that is essentially vacuum is contained in inside.
(table 12) dehydration conditions
Project Condition
Dehydration temperaturre 1100℃
Dewatering time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
Sintering condition
Project Condition
Sintering temperature 1400℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of tubular porous plastid 109C is 2.1g/cm 3, be the Vitrea density (2.2g/cm of complete transparence 3) 95%.Then, above-mentioned plug 107A is inserted among the translucent glass cylinder 109B, add hot wire drawing and begin side, make its fusion sealing, become state shown in Figure 15.
(embodiment 9)
The sintering that will under the condition of table 13, dewater with the tubular porous plastid 109C of the tubular of perforate on the same central shafts of making of embodiment 7 is processed the translucent glass cylinder 109B that the separated foam that is essentially vacuum is contained in inside.
(table 13) dehydration conditions
Project Condition
Dehydration temperaturre 1100℃
Dewatering time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
Sintering condition
Project Condition
Sintering temperature 1350℃
Programming rate 2 ℃/minute
The sintering temperature retention time 4 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of tubular porous plastid 109C is 2.0g/cm 3, be the Vitrea density (2.2g/cm of complete transparence 3) 91%.Then, above-mentioned plug 107A is inserted among the translucent glass cylinder 109B, add hot wire drawing and begin side, make its fusion sealing, become state shown in Figure 15.
(embodiment 10)
The sintering that will under the condition of table 14, dewater with the tubular porous plastid 109C of the tubular of perforate on the same central shafts of making of embodiment 7 is processed the translucent glass cylinder 109B that the separated foam that is essentially vacuum is contained in inside.
(table 14) dehydration conditions
Figure GSB00000639905400301
Sintering condition
Project Condition
Sintering temperature 1350℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of tubular porous plastid 109C is 1.8g/cm 3, be the Vitrea density (2.2g/cm of complete transparence 3) 82%.Then, above-mentioned plug 107A is inserted among the translucent glass cylinder 109B, add hot wire drawing and begin side, make its fusion sealing, become state shown in Figure 15.
(comparative example 2)
The sintering that will under the condition of table 14, dewater with the tubular porous plastid 109C of the tubular of perforate on the same central shafts of making of embodiment 7 is processed the translucent glass cylinder 109B that separated foam is contained in inside.
In comparative example 2, in processed, the sintering processes, all do not reduce pressure in the inside of quartzy furnace core tube 162.In addition, in sintering processes, use helium as non-active gas.
(table 15) dehydration conditions
Sintering condition
Figure GSB00000639905400312
In this stage, the average density of tubular porous plastid 109C is 2.1g/cm 3, be the Vitrea density (2.2g/cm of complete transparence 3) 95%.Then, above-mentioned plug 107A is inserted among the translucent glass cylinder 109B, add hot wire drawing and begin side, make its fusion sealing, become state shown in Figure 15.
Wire-drawing process
Then; The plug 107A that embodiment 7 to 10 and comparative example 2 made and translucent glass cylinder 109B are attached to the heating furnace (below be called fiber drawing furnace) of wire drawing machine from the part insertion of fusion sealing; Space between limit plug 107A and the half sintered glass cylinder is set to decompression state; Clear glassization carry out with the glassy layer of translucent in the limit; Simultaneously, the limit is integrated with plug 107A and translucent glass cylinder 109B fusion, and the limit wire drawing becomes the glass optical fiber that external diameter is about 125 μ m.Here, decompression state is through link to each other vacuum draw pump and aspirate realization of the open end at the handle 155 of the quartzy type of glass that is connected with translucent glass cylinder 109B.The decompression degree of this moment is about 100Pa.
During wire drawing, at 2 layers of UV gel-type resin of outside of fiber coating, irradiation ultraviolet radiation behind the cured resin, is wound on the spool through the coiling capstan winch.In addition, with the inboard of coating be called main stor(e)y, the outside is called sublevel,, sublevel the earth little according to their Young modulus main stor(e)y selected material.Drawing speed in the present embodiment is the 2000m/ branch.
To the various SMF that make with above-mentioned condition, measure bad incidence and the transmission characteristic of bubble in the wire drawing, its result is shown in table 16, table 17.
In addition, the bad incidence of the bubble in the wire drawing is checked with the defect of optical fiber pick-up unit that is shown in Fig. 8.
(table 16)
Bubble fraction defective (l/km)
Embodiment 1; SMF (1) 0.001
Embodiment 2; SMF (2) 0.001
Embodiment 3; SMF (3) 0.001
Embodiment 4; SMF (4) 0.002
Comparative example 1; SMF (5) 0.01
Figure GSB00000639905400331
Any one cutoff wavelength λ cc of the optical fiber of present embodiment in 1310nm or the wavelength region may more than the 1310nm, can guarantee single mode operation all at 1310nm or below the 1310nm.
In addition, said here cutoff wavelength is the cable cut-off wavelength λ cc that G.650 defines in the standard at ITU-T.
In addition, any one of the optical fiber of present embodiment is 0.40dB/km or below the 0.40dB/km, becomes the abundant little optical fiber of absorption loss of hydroxyl (OH) in the loss of 1385nm.
In addition, the tension force that is equivalent to for about 2% length growth rate of the total length of the optical fiber after the wire drawing is given on the limit, and Bian Yijuan investigates the intensity of this optical fiber to other spools.Its result can confirm can not cause fracture, is no problem optical fiber.
Like this, the optical fiber of present embodiment is on the surface of translucent glass cylinder 109B or open pore is arranged, or has when concavo-convex, can not cause special worry owing to the problems such as strength deterioration that cause from sneaking into of the polluter in the heating furnace.That is, this be because, translucent glass cylinder 109B is sintered to bubble or the concavo-convex degree that the opening of polluter is not sneaked on its surface.
On the other hand, the dehydration sintering processes atmosphere gas of tubular porous plastid 109C is not set to decompression state, and in sintering processes, has used in the comparative example 2 (SMF (5)) of helium, though transmission characteristic is no problem, the bubble fraction defective uprises.Infer this be because, in translucent glass cylinder 109B, dissolved in the big helium of solubleness, its this helium foaming in wire drawing forms the cavity in optical fiber.
(embodiment 11)
In the present embodiment, in proportional circle cylindrical shell 109B, add fluorine.In the time of will dewatering sintering with the tubular porous plastid 109C of perforate on the embodiment 7 same central shafts of making, add fluorine, process the translucent glass cylinder 109B that the separated foam that is essentially vacuum is contained in inside according to the condition of table 18.
(table 18) dehydration conditions
Figure GSB00000639905400341
The fluorine adding conditional
Figure GSB00000639905400351
Sintering condition
Project Condition
Sintering temperature 1350℃
Programming rate 2 ℃/minute
The sintering temperature retention time 3 hours
Furnace pressure 100Pa
The mother metal revolution 10 rev/mins
In this stage, the average density of porous plastid is 2.1g/cm 3, be the Vitrea density (2.2g/cm of complete transparence 3) 95%.
Below, same with other embodiment, plug 107A is inserted among the translucent glass cylinder 109B; Add hot wire drawing and begin side; After making its fusion sealing, insert fiber drawing furnace from the part of fusion sealing, the space between limit this plug 107A and the fiber drawing furnace half sintered glass cylinder is set to decompression state; Clear glassization carry out with translucent glass cylinder 109B in the limit; Simultaneously, the limit is integrated with this plug 107A and translucent glass cylinder 109B fusion, and the limit wire drawing becomes the glass optical fiber 151 that external diameter is about 125 μ m.In wire drawing, implement to coat, obtain not having bubble residual in the glass optical fiber after the wire drawing, the coating external diameter that intensity is also no problem is about the optical fiber of 250 μ m.The refractive index of the refractive index ratio pure silicon dioxide glass of the coating portion of interpolation fluorine is low by 0.4%, like present embodiment, also the little zone of refractive index can be set in the part of coating portion.
The optical fiber manufacturing method that the present invention relates to is applied to the optical fiber manufacturing method that has sandwich layer and clad, have various index distribution characteristics; It is a kind of beneficial method; Particularly, the increase that is suitable for losing is little, wide band WDM transmits excellent methods for optical fiber manufacture, is useful; Particularly, be fit to single-mode fiber (Single Mode Fiber; Below be called SMF) etc. optical fiber manufacturing method.
According to the present invention; In dehydration procedure with the dehydration of tubular porous plastid; Under reduced pressure, under any one the condition at least under the atmosphere of nonactive body and halogen gas or under the atmosphere of non-active gas and halogen chemical compound gas; The tubular porous plastid is dewatered, in sintering circuit, with the tubular porous plastid of dehydration under reduced pressure sintering reach and become the translucent glass cylinder that contains separated foam.Have again; To have sandwich layer and be the bar-shaped plug that comprises quartzy type glass and insert in this translucent glass cylinder; The limit is to having inserted the translucent glass cylinder heating of this plug; The clad ground that the limit makes plug and the fusion of translucent glass cylinder is integrated and the semi-transparent circle cylindrical shell is become is made up of clear glass carries out wire drawing, makes optical fiber.Therefore, do not use expensive helium, can make large-scale fibre parent material, in addition,, therefore can reduce the manufacturing cost of optical fiber owing to can make the manufacturing equipment long lifetime yet and omit operation in the short time.
[embodiment 3]
Figure 17 is the process flow diagram of operation that the embodiment 3 of the optical fiber manufacturing method that the present invention relates to is shown.The optical fiber manufacturing method of this embodiment comprises the 1st prefabrication production process (step S301) and dehydration sintering circuit (step S302) and the 2nd prefabrication production process (step S303) and wire-drawing process (step S304).
At first, in the 1st prefabrication production process,, make the material that forms porous preform layer 309C having sandwich layer 303A and being the periphery deposited glass particulate of bar-shaped plug 307A.Be referred to as the 1st prefabrication 310.
Then, in the dehydration sintering circuit, the 1st prefabrication 310 is put into for example dehydration-sintering furnace, the 1st prefabrication 310 is carried out processed and sintering processes.This processed and sintering processes be sintered porous matter mother metal layer 309C under defined terms, processes the translucent glass mother metal layer 309B of the translucent glass state that contains separated foam.That is, the sintering processes of will not dewatering proceeds to porous preform layer 309C and becomes transparent fully.
In addition, in the 2nd prefabrication production process, making will have been carried out processed and sintering processes in above-mentioned dehydration sintering circuit the 1st prefabrication 310 inserts as the material among the sleeve pipe 313B of glass tube.Be referred to as the 2nd prefabrication 320.
Have again; In wire-drawing process, the limit is to the heating of the 2nd prefabrication 320, and the limit makes translucent glass mother metal layer 309B and sleeve pipe 313B fusion integrated; And make translucent glass mother metal layer 309B become the clad 309A ground that constitutes by clear glass and carry out wire drawing, make optical fiber 351.
The methods for optical fiber manufacture of this embodiment, through making optical fiber 351 according to such operation, owing to can use OVD device in the past, and can use the thick plug 307A of external diameter, therefore can improve the deposition efficiency of glass granules.In addition,, therefore compare, can reduce manufacturing cost with RIT method in the past owing in clad, reduced the usage ratio of expensive sleeve pipe 313B.In addition; Because being inserted sleeve pipe 313B, the 1st prefabrication 310 carries out wire drawing; Therefore; Even on the surface of translucent glass mother metal layer 309B or open pore is arranged or have concavo-convex, can not cause yet since the contained polluter of atmosphere gas in the fiber drawing furnace sneak into the problems such as strength deterioration that cause.
Below, illustrative embodiment.In addition, degree no problem on understanding content is recorded and narrated drawing, and its shape is not necessarily dwindling according to reality.In addition, in the present embodiment, the short of special instruction of all characteristics of optical fiber, then be with ITU-T G.650 in regulation be defined as benchmark.
(embodiment 12)
Figure 18 is the drawing that optical fiber 351 refractive index profiles of embodiment 12 making are shown.Shown in figure 18, because optical fiber 351 has the index distribution of ladder refractive index type, therefore have the diffusing wavelength of zero in 1.3 μ m band territory, be so-called SMF.In Figure 18; Optical fiber 351 becomes the rhythmo structure that forms the section concentric circles, forms bar-shaped sandwich layer 303A along central axis, and; With this sandwich layer 303A is the center, and radius vector is to extroversion each layer of order formation with the 1st clad 305A, the 2nd clad 309A and the 3rd clad 313A.In addition, the clad of implementing in the outside of clad 313A omits.
The part that constitutes by sandwich layer 303A and the 1st clad 305A be with after the corresponding part of plug 307A stated.If only plug 307A is observed, the external diameter of sandwich layer 303A and the 1st clad 305A is 4.8/1 than (below be called coating/core than).In addition, in the present embodiment, the external diameter of so-called sandwich layer 303A is meant the diameter with respect to peaked 1/2 part of the specific refractivity difference of the sandwich layer 303A of the refractive index of the 1st clad 305A.
The part of being made up of sandwich layer 303A, the 1st clad 305A and the 2nd clad 309A promptly, is added the part of the 2nd clad 309A on plug 307A, be with after the 1st prefabrication 310 corresponding parts stated.In addition, the part of being made up of sandwich layer 303A, the 1st clad 305A, the 2nd clad 309A and the 3rd clad 313A promptly, is added the part of the 3rd clad 313A on the 1st prefabrication 310, be with after the 2nd clad 320 corresponding parts stated.
The making of plug
In the present embodiment, at first use the method same, promptly became the core soot 307B of plug 307A afterwards with VAD method making shown in Figure 3 with embodiment 1.
Then, this core soot 307B is carried out processed and sintering processes.Thus, core soot 307B is become the plug 307A that contains sandwich layer 303A and the 1st clad 305A by clear glassization.
The stretching of plug
Then, this plug 307A that contains sandwich layer 303A and the 1st clad 305A by clear glassization is used vertical electric furnace stretching device heat drawing, make it become the about 50mm of external diameter.In addition, the thermal source that uses in this heat treated and the stretch processing is not limited only to electric furnace, also can be flames such as oxyhydrogen flame or flame passes etc.At this moment, when having hydroxyl (OH) pollution problems, not preferred oxyhydrogen flame, and preferred electric furnace or flame passes.
The formation of porous preform layer (the 1st prefabrication production process)
Then, use the method same, use OVD method deposit synthetic glass particulate shown in Figure 4, form porous preform layer 309C and make the 1st prefabrication 310 in the plug 307A periphery that stretches with embodiment 1.Porous preform layer 309C became translucent glass mother metal layer 309B afterwards, so that finally become the part of the 3rd clad 309A by transparence.
In addition, in this operation, finally become diameter and the diameter ratio thickness that is about the glass granules of 9/1 ground adjustment deposit shown in figure 18 of final sandwich layer 303A of the 2nd clad 309A of fully transparent glass according to porous preform layer 309C.In the adjustment of this thickness, decide the external diameter of the porous preform layer 309C in the deposit and the variation of weight through non-contacting laser displacement gauge and weight instrumentation, sustained firing is up to the amount of glass of deposit for regulation.In this stage; The average density of porous preform layer 309C (that is, the general assembly (TW) weight of porous preform layer 309C that deducts the weight of the plug 307A volume of porous preform layer 309C that deducts the volume of plug 307A with cumulative volume removes the value that obtains) is about 0.25g/cm 3Density about this porous preform layer 309C; Through making discovery repeatedly with various density; For degree with the shape that can keep porous preform layer 309C firm, can fully dewater and optimize the deposition efficiency of frit in addition; As average density, preferred 0.2～0.4g/cm 3About.
In addition; The optimization of the average density of this porous preform layer 309C; Through the external diameter of monitoring porous preform layer 309C and the variation of weight, simultaneously, the unstrpped gas the when deposit of synthetic glass particulate is carried out in change and the input amount of burning gases, the translational speed of pulverizing jet 331 are carried out.In addition, ask this just when the time find that the temperature of the deposit face of porous preform layer 309C is set to 400 ℃～600 ℃ scope can carry out optimization well.
Transformation (dehydration sintering circuit) to translucent mother metal layer
With having formed the sintering that dewaters under the 1st prefabrication 310 usefulness accomplishing the porous preform layer 309C of deposit around the plug 307A and the constitute condition of dehydration-sintering furnace 330 at table 19 shown in Figure 23, make porous preform layer 309C change translucent glass mother metal layer 309B into.
In Figure 23, dehydration-sintering furnace 330 has the stove core barrel made from silica glass 335, and the inside of stove core barrel 335 is full of helium (He) gas and chlorine (Cl 2) gas.In addition; Import all gases from the gas introduction port 338 that is arranged on the setting of stove core barrel 335 belows with the flow shown in the table 19; Simultaneously, an amount of gas is discharged from the gas discharge outlet 339 that is arranged on stove core barrel 335 tops, the pressure in the stove core barrel 335 remains the value of regulation thus.The 1st prefabrication 310 is put into this stove core barrel 335,, carry out the dehydration sintering of porous preform layer 309C through well heater 337 heating that are arranged on stove core barrel sidepiece.Here; So-called dehydration sintering is meant processed and sintering processes, can certainly distinguish independent enforcement, but for simplifying manufacturing process or reducing manufacturing cost; In the present embodiment, will under defined terms, carry out this processed and sintering processes simultaneously as one of characteristic.
(table 19)
Temperature about the dehydration sintering; In the present embodiment; In the temperature range that can the porous preform layer 309C that be made up of pure silica glass in fact be become the degree of translucent glass state; And be set to bring the temperature range of damage can not for stove core barrel 335, maximum temperature is set at 1350 ℃ of sintering processes of dewatering.
In addition, even use the so such fluorine compound gas of chloride compound gas, silicon tetrafluoride of thionyl chloride, also can obtain dehydration.But, when using fluorine compound gas,, be necessary that therefore the variation of considering index distribution uses because the refractive index of silica glass reduces.In addition; When using fluorine compounds; The softening temperature of glass is compared remarkable reduction with pure silica glass, even therefore for obtaining the low translucent glass mother metal layer 309B that also is easy to transparence of temperature, be necessary maximum temperature is set at lower than the occasion of pure silica glass.
In the stage that the dehydration sintering circuit finishes, translucent glass mother metal layer 309B shown in Figure 24 pattern, becomes the state that contains the separated foam 309a that physically isolates with atmosphere gas on every side in a large number.With this state as " translucent glass state ".In this " translucent glass state ", all contain the separated foam of the bubble that conduct and atmosphere gas on every side physically isolates basically equably, be gonorrhoea and opaque state in appearance.In addition, smooth surface and have gloss.In addition, the density of the translucent glass mother metal layer 309B of this moment according to the result of above-mentioned algorithm calculations, is the 2nd clad 309A density (2.2g/cm that finally becomes complete clear glass 3) 95%, that is, and 2.09g/cm 3
The density of base glass material layer depends on heating-up temperature, heat time heating time and glass granules and composition and changes.If heating-up temperature is high, density uprises morning (promptly in the short time), and transparence finished in the short time.If temperature is low, up to becoming transparent time lengthening, have again, in the temperature lower than the softening temperature of glass, sintering does not carry out, and therefore can not cause transparence yet.When same temperature, heat time heating time, the density of elder's base glass material layer uprised, if but because complete transparence, heating after this is just nonsensical, so the progress of transparence is mainly arranged by temperature factor.
For the composition of glass granules, pure silica glass with added in the silica glass of fluorine, softening temperature is different, pure silica glass is high.Therefore, for pure silicon dioxide microparticle transparence, need higher temperature.In the present embodiment, with the temperature conditions that can not damage stove core barrel 335, promptly; Preferred below 1350 ℃ or 1350 ℃; With about 1400 ℃ be the upper limit, and, be necessary to set the condition that manufacturing time does not prolong from the viewpoint of manufacturing cost; Therefore, should improve the density of base glass material as much as possible in this temperature range.
And the result of the sintered porous matter mother metal layer 309C of dehydration judges under all temps, heat time heating time, the density range of translucent glass mother metal layer 309B, if consider in wire-drawing process after this, to prevent the viewpoint that bubble is residual, and preferred 1.8g/cm 3～2.15g/cm 3About, on the other hand, if consider to improve the productive viewpoint of drawing speed, preferred 2.0g/cm 3～2.15g/cm 3About.And, if 1.8g/cm 3Or 1.8g/cm 3Below, even about drawing speed divides to the 100m/ of productivity extreme difference slowly, also can residual bubble in optical fiber, can not become product.On the other hand, average density surpasses 2.15g/cm 3State, from the above-mentioned temperature and the viewpoint of manufacturing cost, can not realize at the heated perimeter that allows.
Be inserted into (the 2nd prefabrication production process) in the sleeve pipe
Then, the 1st prefabrication 310 that will around plug 307A, form translucent glass mother metal layer 309B formation inserts among the sleeve pipe 313B of the glass tube of preparing in addition, makes the 2nd prefabrication 320.Sleeve pipe 313B used herein is with being called as the material that contains " anhydrous synthetic quartz " through the synthetic silica glass of chemical reaction, and the content of hydroxyl (OH) base is 1ppm or below the 1ppm.For example, the SUP-F300 that makes of commercially available SHIN-ETSU HANTOTAI quartzy (strain) etc. promptly is this material.In addition, the size of sleeve pipe 313B suitably selects to use the sleeve pipe size of thickness of the optical fiber of the core diameter that becomes expectation after having the sufficient internal diameter that inserts the 1st prefabrication 310 and having wire drawing.At this moment, also can set the stretching external diameter of plug 307A and external diameter and the density of porous preform layer 309C from the size of pre-prepd sleeve pipe 313B.In addition, this sleeve pipe 313B cleans through hydrofluoric acid aqueous solution etc. in advance, uses with the state of cleaning.
To the insertion of the sleeve pipe 313B of first prefabrication 310, shown in figure 25, to keeping the sleeve pipe 313B of vertical direction, the 1st prefabrication of slowly leaving behind from the top carries out.At this moment, shown in figure 26, also can be from laterally the 1st prefabrication 310 being inserted the sleeve pipe 313B that keeps horizontal direction.In addition, during insertion, for not polluting the inner face of sleeve pipe 313B, can the limit clean nitrogen, pure air etc. be blown into mobile between sleeve pipe 313B and the 1st prefabrication 310, sneak into foreign matter when preventing to implement to insert operation.
After the 1st prefabrication inserts and finishes; Shown in figure 27, spray the oxyhydrogen flame that ejects from pulverizing jet 341 to the end of the wire-drawing direction side of the 2nd prefabrication 320, make its heating and melting; With the open-ended fusion sealing of sleeve pipe 313B, that the end of the end of sleeve pipe 313B and the 1st prefabrication 310 is integrated.The purpose of carrying out this processing is from following reason.Promptly; When in fiber drawing furnace, carrying out the sealing of opening of sleeve pipe 313B, the 2nd prefabrication 320 can the atmosphere gas in this opening part is sneaked into this fiber drawing furnace contained impurity, thus; Might pollute the surface of inner face and the translucent glass mother metal layer 309B of sleeve pipe 313B; Therefore, before putting into fiber drawing furnace, carry out the fusion sealing of sleeve pipe 313B in advance.In addition, if the end fusion of the end of sleeve pipe 313B and the 1st prefabrication 310 is integrated, can shorten when wire drawing begins to transition is the time of steady state (SS).
In addition, as fusion the 2nd prefabrication 320 open-ended thermals source, in the present embodiment, carrying out through the injection of oxyhydrogen flame, but be not limited thereto, also can be the injection of flame passes or by heating of electric furnace etc.
In addition; After inserting the 1st prefabrication 310 in the sleeve pipe 313; The also opening of the end of closed casing 313B not, but shown in figure 28 comes the fusion sealing through before the insertion of the 1st prefabrication 310, in advance the end of the wire-drawing direction side of sleeve pipe 313B being added thermal cut.Thus, can prevent the pollution of impurity equally with method shown in Figure 27.In addition, shown in figure 28 when the 313B of fusing sleeve pipe, in the end of sleeve pipe 313B, the black direction of arrow in edge is tractive force in addition, and the limit fuses through the oxyhydrogen flame heating that ejects from pulverizing jet 341.
Wire-drawing process
Then; The 2nd prefabrication 320 is inserted in the fiber drawing furnace from part one side of above-mentioned fusion sealing; The limit is arranged to the space (with reference to Figure 27) between sleeve pipe 313B and the translucent glass mother metal 309B to be in a ratio of with atmospheric pressure the state of decompression; The limit makes translucent glass mother metal layer 309B and sleeve pipe 313B fusion is integrated and make translucent glass mother metal layer 309B clear glassization ground carry out wire drawing, makes the glass optical fiber 361 that external diameter is about 125 μ m.Thus, translucent glass mother metal 309B changes the 2nd clad 309A into, and sleeve pipe 313B changes the 3rd clad 313A into,, changes final form separately into that is.In addition, here, decompression state through being connected not shown vacuum draw pump in the fusion closed side of sleeve pipe 313B and the open end of opposition side, is reached by the gas between this vacuum draw pump suction sleeve pipe 313B and the translucent glass mother metal layer 309B.
In wire-drawing process, at 2 layers of UV gel-type resin of optical fiber 351 surface coated, and irradiation ultraviolet radiation, solidify this resin, process and coat the optical fiber that external diameter is about 250 μ m, be wound on the spool through the coiling capstan winch.The tension force that is equivalent to for about 2% length growth rate of the total length of the optical fiber after the wire drawing 351 is given on the limit, and Bian Yijuan investigates the intensity of this optical fiber 351 to other spools.Its result can confirm can not cause fracture, is no problem optical fiber.
In addition, use the defect of optical fiber pick-up unit, confirming does not have the residual separated foam that is present in translucent glass mother metal layer 309B in the glass optical fiber 361 in wire-drawing process.
Particularly; With defect of optical fiber pick-up unit shown in Figure 8; From the light such as axle illuminating laser beam of transverse direction, accept forward scattering light with image sensor, through detecting the unusual of this scattered intensity distribution patterns from this glass optical fiber to the glass optical fiber the wire-drawing process; The cavity blemish of detection bubble etc. is kept watch on the bubble in the glass optical fiber.
Its results verification in the glass optical fiber 361 behind wire-drawing process, does not have the separated foam that exists among the residual translucent glass mother metal layer 309B.
The result who is determined at the transmission characteristic of the SMF that makes under the condition of present embodiment record is shown in table 20
The optical fiber 351 any one cutoff wavelength λ cc of present embodiment in 1310nm or the wavelength region may more than the 1310nm, can guarantee single mode operation all at 1310nm or below the 1310nm.
In addition, said here cutoff wavelength is the cable cut-off wavelength λ cc that G.650.1 defines in the standard at ITU-T.
In addition, optical fiber 351 any one loss at 1385nm of embodiment are 0.40dB/km or below the 0.40dB/km, become the abundant little optical fiber of absorption loss of hydroxyl (OH).
In addition, even disperse (Polarization Mode Dispersion in polarization; Below, become PMD) in also be shown as fully little value.
Then, carry out optical fiber 351 is exposed to the experiment in the hydrogen.The hydrogen here exposes experimental conditions and is made as IEC-60793-2B 1.3 defined terms.Promptly; Optical fiber 351 at room temperature is exposed in the hydrogen in the hydrogen dividing potential drop atmosphere gas of about 0.01atm, keeps this hydrogen exposed state, the transmission loss under the light signal of wavelength 1240nm is compared increase 0.03dB/km with the transmission loss (initial value) before hydrogen exposes or more than the 0.03dB/km; Afterwards; Be taken out in the atmosphere, place more than 14 days or 14 days, transmit the mensuration of loss.
Transmission loss after hydrogen exposes and the variable quantity (b-a) that is lost by the transmission that the hydrogen exposure causes are shown in table 21.Loss increases and reduces, and becomes to be fit to the optical fiber that broadband WDM transmits.
(table 21)
(embodiment 13)
Figure 19 is the drawing that optical fiber 352 refractive index profiles of embodiment 13 making are shown.Shown in figure 19, because optical fiber 352 has the index distribution of stage type, therefore be to have the loose dispersion shifted optical fiber (Dispersion-Shifted Fiber: below be called DSF) of wavelength of zero in 1.55 μ m band territory.In Figure 19; Optical fiber 352 becomes the rhythmo structure that forms the section concentric circles; Form sandwich layer 303A along central axis; Afterwards, radius vector is to extroversion from central division, and each layer that is formed by the order according to side sandwich layer 304A, the 1st clad 305A, the 2nd clad 309A and the 3rd clad 313A constitutes.In addition, the clad of implementing in the outside of the 3rd clad 313A omits.
The part that constitutes by sandwich layer 303A and side sandwich layer 304A and the 1st clad 305A be with after the corresponding part of plug 307A stated.If only the part of plug 307A is observed, the external diameter of side sandwich layer 304A and the 1st clad 305A is 2.3/1 than (below be called coating/core than).In addition, in the present embodiment, the external diameter of so-called side sandwich layer 304A is meant the diameter with respect to peaked 1/2 part of the specific refractivity difference of the side sandwich layer 304A of the refractive index of the 1st clad 305A.
The part of being made up of sandwich layer 303A, side sandwich layer 304A, the 1st clad 305A and the 2nd clad 309A promptly, is added the part of the 2nd clad 309A on the part corresponding with plug 307A, be with after the 1st prefabrication 310 corresponding parts stated.In addition,, that is, on the 1st prefabrication 310, add the part of the 3rd clad 313A, be and the 2nd clad 320 corresponding parts by the part that sandwich layer 303A, side sandwich layer 304A, the 1st clad 305A, the 2nd clad 309A and the 3rd clad 313A form.
In the present embodiment, at first make the core soot 307B of the 307A that became plug afterwards with the VAD method.Figure 29 is the mode chart of the process of the VAD method core manufacturing soot 307B of explanation through present embodiment, with core soot 307B part as profile.In Figure 29, in the VAD method,, send into silicon tetrachloride (SiCl by gasification through containing the core pulverizing jet 321 of multiple tubular construction 4), germanium tetrachloride (GeCl 4), oxygen (O 2) and hydrogen (H 2) gas 326 that constitutes, and ignition.And the reaction that in flame, is hydrolyzed obtains the synthetic glass particulate.This synthetic glass particulate is injected into not shown kind rod and adheres to.
The synthetic glass particulate that sprays is deposited on kind of rod 311, forms the sandwich layer soot 303B that became sandwich layer 303A afterwards.And, plant excellent 311 and pull out to the last direction of Figure 29 lentamente while rotating.
On the top of core pulverizing jet 321 similar side core pulverizing jet 323 is set, sends into silicon tetrachloride (SiCl 4), germanium tetrachloride (GeCl 4), oxygen (O 2) and hydrogen (H 2) gas 328 that constitutes, and reaction forms the side sandwich layer soot 304B that became side sandwich layer 304A afterwards in the periphery of sandwich layer soot 303B.
On the top of side core pulverizing jet 323 similar coating pulverizing jet 322 is set, sends into silicon tetrachloride (SiCl 4), oxygen (O 2) and hydrogen (H 2) gas 327 that constitutes, and reaction forms the clad soot 305B that became the 1st clad 305A afterwards in the periphery of side sandwich layer soot 304B.Thus, become the bar-shaped core soot 307B that forms the regulation thickness.
Then, core soot 307B is carried out processed and sintering processes.Thus, core soot 307B is become plug 307A by clear glassization.
Then, use vertical this plug of electric furnace stretching device heat drawing 307A, and make its external diameter become about 50mm.Have again, use OVD method deposit silica glass particulate, form the porous preform layer and also form the 1st prefabrication in the periphery of the plug 307A of heat drawing.In this stage, the thickness of glass granules of adjustment deposit, the external diameter when making the porous preform layer become transparent glass fully and become shown in Figure 19 about 6/1 ratio at the ratio of the external diameter of the side sandwich layer 304A of this state.And, to around plug 307A, accomplishing the 1st prefabrication of the deposit of porous preform layer, carry out the dehydration sintering same with embodiment 12, change the porous preform layer into translucent glass mother metal layer.
Then, the 1st prefabrication is inserted in the sleeve pipe of preparing in addition as glass tube, make the 2nd prefabrication, again the front end fusion of sleeve pipe is sealed.Then; The limit is adjusted into the state that is in a ratio of decompression with atmospheric pressure with the space between translucent mother metal layer and the sleeve pipe, and the limit is with translucent glass mother metal layer clear glassization, simultaneously; The limit is integrated with translucent glass mother metal layer and sleeve pipe fusion, and the limit wire drawing becomes the glass optical fiber of the about 125 μ m of external diameter.
In addition, same with embodiment 12, in wire drawing, implement coating, obtain coating the optical fiber 352 that external diameter is about 250 μ m.Same with embodiment 12, confirming does not have the residual of bubble in the glass light in wire drawing, and no problem on the intensity.
The transmission characteristic of measuring the DSF that makes under the condition of record in the present embodiment is shown in table 22.
Figure GSB00000639905400471
(embodiment 14)
Figure 20 is the drawing that optical fiber 353 refractive index profiles of embodiment 14 making are shown.Shown in figure 20; Because optical fiber 353 has the index distribution of fan (セ グ メ Application ト) type, therefore be that to be with the dispersion value in territory be the non-zero dispersion displacement optical fiber (Non-ZreoDispersion-Shifted Fiber: below be called NZDSF) of the scope of 1.5～8ps/nm/km to 1.55 μ m.In Figure 20, optical fiber 353 becomes the rhythmo structure that forms the section concentric circles, forms plug 307A along central axis, and afterwards, radius vector is to extroversion from central division, and each layer that is formed by the order according to the 1st clad 309A and the 2nd clad 313A constitutes.In addition, the clad of implementing in the outside of the 2nd clad 313A omits.
The plug 307A heat drawing that to be made by the VAD method is to the about 40mm of external diameter; Again in the periphery of the plug 307A that stretches with OVD method deposit silica glass particulate; Form the porous preform layer and (became translucent glass mother metal layer afterwards; Become the part of the 1st clad 309A afterwards), make the 1st prefabrication 310.In this stage, the thickness of glass granules of adjustment deposit, the external diameter when making the porous preform layer become transparent glassy layer fully and become shown in Figure 20 about 2.5/1 at the ratio of the external diameter of the plug of this state.And, same with embodiment 12, with the 1st prefabrication 310 dehydration sintering, the porous preform layer is processed translucent glass mother metal layer (becoming the part of the 1st clad 309A afterwards).
Then, the 1st prefabrication 310 is inserted in the sleeve pipe of preparing in addition as glass tube (becoming the part of the 2nd clad 313A afterwards), make the 2nd prefabrication 320.
Then, carry out the processing same, the optical fiber 353 that obtains expecting with embodiment 12.And same with embodiment 12, confirming does not have the residual of bubble in the glass light in wire drawing, and no problem on the intensity.The result who measures the transmission characteristic of the NZDSF that makes under the condition of record in the present embodiment is shown in table 23.
Figure GSB00000639905400491
In addition,, can be set at the dispersion value of 1550nm through index distribution optimization with sandwich layer 303A, for example ,-1.5～-8ps/nm/km, this is that this area researchist understands easily.
(embodiment 15)
Figure 21 is the drawing that the refractive index profile of the optical fiber 354 that embodiment 15 makes is shown.Shown in figure 21, optical fiber 354 is the optical fiber that has the zone lower than outermost clad refractive index in the sandwich layer periphery of the refractive index with stage type.In Figure 21, optical fiber 354 becomes the rhythmo structure that forms the section concentric circles, forms plug 307A along central axis, and afterwards, radius vector is to extroversion from central division, and each layer that is formed by the order according to the 1st clad 309A and the 2nd clad 313A constitutes.In addition, the clad of implementing in the outside of the 2nd clad 313A omits.
The plug 307A heat drawing that to make through the VAD method is to the about 30mm of external diameter; Again in the periphery of the plug 307A that has stretched with OVD method deposit silica glass particulate; Form the porous preform layer and (became translucent glass mother metal layer afterwards; Become the part of the 1st clad 309A afterwards), make the 1st prefabrication 310.In this stage, the thickness of glass granules of adjustment deposit, the external diameter when making the porous preform layer become transparent transparent glass layer fully and become shown in figure 21 about 6/1 at the ratio of the external diameter of the plug of this state.And,,, the porous preform layer is processed translucent glass mother metal layer (becoming the part of the 1st clad 309A afterwards) with the porous preform pull-up water sintering of the 1st prefabrication 310 according to the condition of showing table 24 down.
Table 24
Figure GSB00000639905400501
Then, the 1st prefabrication 310 is inserted in the sleeve pipe of preparing in addition (becoming the part of the 2nd clad 313A afterwards) as the glass tube of front end fusion in advance sealing, make the 2nd prefabrication 320.
Then; The limit is adjusted into the state that is in a ratio of decompression with atmospheric pressure with the space between translucent mother metal layer and the sleeve pipe, and the limit is with translucent glass mother metal layer clear glassization, simultaneously; The limit is integrated with translucent glass mother metal layer and sleeve pipe fusion, and the limit wire drawing becomes the glass optical fiber of the about 125 μ m of external diameter.
In addition, carry out the processing same, in wire drawing, implement coating with embodiment 12, obtain not having in the glass light in wire drawing also no problem on the residual and intensity of bubble, coat the optical fiber 354 that external diameter is about 250 μ m.Like present embodiment, also the little zone of refractive index can be set in the part of clad.
(embodiment 16)
Figure 22 is the drawing that the refractive index profile of the optical fiber 355 that embodiment 16 makes is shown.Shown in figure 22, optical fiber 355 is the optical fiber that has the zone lower than outermost clad refractive index in the sandwich layer periphery of the refractive index with stage type.In Figure 22; Optical fiber 355 becomes the rhythmo structure that forms the section concentric circles, forms plug 307A along central axis, afterwards; Radius vector is to extroversion from central division, and each layer that is formed by the order according to the 1st clad 309A, the 2nd clad 313A and the 3rd clad 314A constitutes.In addition, the clad of implementing in the outside of the 3rd clad 314A omits.
The plug 307A heat drawing that to make through the VAD method is to the about 30mm of external diameter; Again in the periphery of the plug 307A that has stretched with OVD method deposit silica glass particulate; Form the porous preform layer and (became translucent glass mother metal layer afterwards; Become the part of the 1st clad 309A afterwards), make the 1st prefabrication 310.In this stage, the thickness of glass granules of adjustment deposit, the external diameter when making the porous preform layer become transparent transparent glass layer fully and become shown in figure 21 about 6/1 at the ratio of the external diameter 307A of the plug of this state.And,,, the porous preform layer is processed translucent glass mother metal layer with the porous preform pull-up water sintering of the 1st prefabrication 310 according to the condition of showing table 25 down.
Then; The 1st prefabrication 310 and fluorine doping sleeve pipe (becoming the part of the 2nd clad 313A afterwards) are inserted in the sleeve pipe that contains pure silicon dioxide glass (becoming the part of the 3rd clad 314A afterwards) of the front end fusion in advance sealing of preparing in addition, make the 2nd prefabrication 320.
Then; The limit is adjusted into the state that is in a ratio of decompression with atmospheric pressure with the space between translucent mother metal layer and fluorine doping sleeve pipe and fluorine doping sleeve pipe and the pure silicon dioxide glass bushing; The limit is with translucent glass mother metal layer clear glassization; Simultaneously, the limit is integrated with translucent glass mother metal layer, fluorine doping sleeve pipe and the fusion of pure silicon dioxide glass bushing, and the limit wire drawing becomes the glass optical fiber of the about 125 μ m of external diameter.
In addition, carry out the processing same, in wire drawing, implement coating with embodiment 12, obtain not having in the glass light in wire drawing also no problem on the residual and intensity of bubble, coat the optical fiber 355 that external diameter is about 250 μ m.
The embodiment of this instructions record is for illustration of the present invention is described; For various variation; For example; Manufacturing approach (for example, MCVD method, OVD method, PCVD method etc.) with optical fiber or various plugs of more complicated index distribution also can be included in scope of the present invention, and this is that those skilled in the art can make much of.
According to the present invention,, process the 1st prefabrication at the periphery deposited glass particulate formation porous preform layer of plug; For the 1st prefabrication, the porous preform layer dewater and sintering up to becoming the translucent glass mother metal layer that contains separated foam, the 1st prefabrication that will carry out this dehydration and sintering again inserts in the glass tube; Process the 2nd prefabrication; For the 2nd prefabrication limit heating, limit wire drawing, make the integrated and translucent glass mother metal layer of translucent glass mother metal layer and glass tube fusion become the clad that constitutes by clear glass; Therefore; Can prolong the manufacturing equipment with in the past through basic former state ground, and the omission of manufacturing process and the optimization of creating conditions, reduce the manufacturing cost of optical fiber.Its result provides high-quality and cheap optical fiber with can not appending exploitation and equipment investment on a large scale.
The optical fiber manufacturing method that the present invention relates to is suitable for the optical fiber manufacturing method that has sandwich layer and clad, have various index distribution characteristics; Being a kind of beneficial method, is to go for transmitting the optical fiber manufacturing method that loss is low, be suitable for broadband WDM transmission excellence.
(embodiment 17)
[plug production process]
In the present embodiment, at first form and contain the not porous preform of the part of clad of sandwich layer, then,, process the clear glass state, make plug this porous preform dehydration sintering with the VAD method.Then, this plug of heat drawing makes its external diameter become about 50mm.
[porous layer formation operation]
Then, with the quartzy type glass granules of OVD method deposit, form the porous layer (porous layer formation operation) of diameter 300mm in the periphery of the plug that has stretched.Figure 30 be explanation adopt the OVD method form porous layer 205A the mode chart of state, with the part of porous layer 205A as vertical section.In the OVD method,, send into the silicon tetrachloride (SiCl of gasification through pulverizing jet 211 4), oxygen (O 2) and hydrogen (H 2) gas 212 that constitutes, ignition.And the reaction that in flame, is hydrolyzed obtains glass granules.This glass granules is injected on the plug 203 of rotation, be deposited on plug 203 around.The thickness of the layer of the glass granules of a deposit is very not thick, so the limit comes and goes pulverizing jet 211 repeatedly, the limit repeatedly its, up to the porous layer 205A that becomes abundant rugosity.The average density of the porous layer 205A that forms like this (that is, will deduct the value that the value of the volume of plug 203 is removed with the weight of porous layer 205A from cumulative volume) is about 0.7g/cm 3
[dehydration sintering circuit]
Figure 31 is the cross-sectional side view of dehydration-sintering furnace that the state of dehydration sintering circuit is shown.With the intermediate member of processing as stated, promptly; The parts that form porous layer 205A in the periphery of plug 203 are arranged in the dehydration-sintering furnace shown in Figure 31 220; The sintering that under the condition of table 25, dewaters is processed porous layer 205A the translucent glass layer 205B (dehydration sintering circuit) of the translucent glass state that contains separated foam.This translucent glass layer 205B is the initial package coating that was become clad afterwards by vitrifacation.
(table 25) dehydration conditions
Figure GSB00000639905400531
Sintering condition
Figure GSB00000639905400532
Dehydration-sintering furnace 220 has: as quartz glass system can be airtight the quartzy stove core barrel 222 and a plurality of of container be arranged on around this quartz stove core barrel 222 the multiple well heater of the ring-type as heater (マ Le チ ヒ one タ) 223 and with quartzy stove core barrel 222 and well heater 223 all coatings the time, form body of heater 227 and the thermal insulation material 226 of between quartzy stove core barrel 222 and multiple well heater 223 and body of heater 227, filling of the shell of dehydration-sintering furnace 220.
In the dehydration sintering circuit, import chlorine (Cl to quartzy stove core barrel 222 inside according to the never illustrated gas introduction port of the flow of the regulation shown in the table 25 2) and helium (He), simultaneously, never illustrated gas discharge outlet is discharged an amount of gas, thus, keeps the value of pressure for stipulating in the quartzy stove core barrel 222.
In the past; In the method for porous layer 205A being processed transparent fully vitreousness; Normally carry out following 2 stage procedures, at first after carrying out thermal dehydration under the temperature below 1200 ℃ or 1200 ℃ that sintering does not carry out, be exposed to and carry out transparence under the hot conditions.But, in method in the past, damage the stove core barrel easily, the energy cost of heating is high.Therefore, in the present invention, import the method that the temperature range that after processed, realizes translucent glass state degree is carried out sintering.
In this stage, the density (2.2g/cm of the material of the above-mentioned clear glass state of the transparence of the average density of translucent glass layer 205B 3) 95% (2.1g/cm 3).In the sintering process of porous layer 205A, increase the combination between particulate through heating, pore reduces, and increase in density transforms to the clear glass state that finally contains bubble hardly.Sintering carry out speed dependent in the particle diameter of temperature and time, particulate and change, but when carrying out sintering with heating furnace, it is fast to carry out speed near surperficial person's sintering of the porous layer 205A of well heater 223.The result of the sintered porous matter layer of dehydration finds under all temps, heat time heating time, and is directly when having the translucent glass layer 205B wire drawing of separated foam, residual for preventing the bubble in wire drawing, as long as the average density of translucent glass layer 205B is 1.8g/cm 3Or 1.8g/cm 3More than, preferred 2.0g/cm 3Or 2.0g/cm 3More than get final product.
In above-mentioned dehydration sintering circuit, both ends are being difficult to receive the radiation from well heater in shape, even the parallel portion of translucent glass layer 205B surface is basic when accomplishing sintering, sintering is not also accomplished at both ends sometimes.Though the wire drawing starting end after in the front end transparence operation stated by clear glassization, the sintering that finishes clearing end in wire drawing imperfect tense, outer gas is invaded inner from the wire drawing clearing end, after wire drawing, having becomes the residual danger of bubble.Therefore, at the sintering of wire drawing clearing end imperfect tense, as appending operation, the sintering on surface is accomplished in the thermal treatment of preferably heating through inflammable gas flame such as electric furnace or hydrogen-oxygen, methane or flame passes at least fully.In addition; From this viewpoint; Shown in figure 32 through using, have corresponding to the independently special well heater 223A of the part of the tapered portion at mother metal both ends, the dehydration-sintering furnace 221 of 223B, can with the topmost of stove core barrel 222 not the design temperature of foot carry out sintering than the well heater highland of other parts.
[front end transparence operation]
Then, the wire drawing of translucent glass layer 205B is begun the leading section clear glassization of side.Promptly; The wire drawing of translucent glass layer 205B is begun the first end insertion heating furnace 230 shown in Figure 33 of side; Carry out thermal treatment, will contain the partially transparent vitrifacation of growing apart from the about 150mm of front end of tapered portion 205C and coupled parallel portion 205D that wire drawing begins the front end of side through well heater 233 heating.Heating furnace 230 have constitute shell body of heater 237, between body of heater 237 and well heater 233, filled thermal insulation material 236.The mother metal diameter of the clear glassization part of translucent glass layer 205B is 170mm, and the mother metal diameter of the part of clear glassization is not 173mm.The heat-treat condition of this moment is as shown in following.So operate, made 1 embodiment of the fibre parent material that the present invention relates to.
Table 26
Project Condition
Heter temperature when mother metal inserts 1400℃
Heter temperature during transparence 1600℃
Programming rate 5 ℃/minute
The transparence temperature hold-time 1 hour
[wire-drawing process]
The leading section that operation is like this made is inserted in the fiber drawing furnace 240 shown in Figure 34 by the fibre parent material of clear glassization and carries out wire drawing.Fiber drawing furnace 240 has: take in the stove core barrel 242 of fibre parent material and the prolongation tube 248 that along the vertical direction stove core barrel 242 is prolonged and be arranged on the carbon system well heater 243 around the stove core barrel 242 and form body of heater 247 and the heat-barrier material 246 of filling between well heater 243 and body of heater 247 of the shell of fiber drawing furnace 240.Usually, stove core barrel 242 is made up of carbon or zirconia, can use the parts that the pipe that is made up of carbon or quartz is set in the inboard of metal cylinder as prolonging tube 248.The result of various trial-productions judges repeatedly; Wire drawing begins the length (length of part from the mother metal leading section to the translucent glass state) of clear glassization part of leading section of side if be in 0.5 times～1 times the length of diameter of the mother metal body parallel portion of translucent glass state, the effect that can obtain stipulating.That is, judged,, before the separated foam of translucent glass state part disappears, just can not carry out wire drawing so if only this length partly is made for the clear glass state.At this moment, the length of so-called leading section is the distance apart from the end of quartzy type of glass granules (initial package coating) attachment portion that is stacked on plug 203.This distance with the mother metal position that when wire drawing begins, is positioned at well heater 243 centers is roughly consistent.And shown in figure 34, the length L 1 that is in the part of clear glass state compares from the center of well heater 243 short to the length L that prolongs tube 248 upper ends 2.That is, clear glass state part all is accommodated in the fiber drawing furnace 240.Through processing such formation, few from the upper opening portion dispersed heat of fiber drawing furnace 240, can reduce power cost.Be 80g at the stove core barrel of fiber drawing furnace 240 tension force during directly for 200mm, wire drawing, the furnace temperature when linear velocity is 1500m/min, wire drawing is 2200 ℃, when electric power is 50kW, the life-span of 3 months life-spans of stove core barrel, well heater is 1 year.
Wire drawing begins the length of the tapered portion 205C that the leading section of side forms when very long; For example; Than mother metal body parallel portion diameter when long; The length of clear glassization part is just according to 0.5 times～1 times of the diameter of above-mentioned mother metal body parallel portion, and preferred tapered portion 205C all by transparence.In addition, as the part of tapered portion, be meant that the mother metal diameter is than the part more than the diameter thin 3% or 3% of mother metal body parallel portion in this instructions.
(embodiment 18)
In embodiment 18, sintering at first will dewater under the condition of table 27 with the mother metals that contain porous layer 205A of embodiment 17 same making.In sintering circuit, use the vacuum pump 225 that is connected on the quartzy stove core barrel 222 with the inner pressure relief of stove core barrel.Porous layer 205A carries out processed and sintering processes in the inside of quartzy stove core barrel 222, becomes the translucent glass layer 205B that the translucent glass state of the separated foam that is essentially vacuum is contained in inside.Become inside and contain the translucent glass layer 205B of the translucent glass state of the separated foam that is essentially vacuum.
(table 27) dehydration conditions
Sintering condition
Project Condition
Sintering temperature 1400℃
Programming rate 5 ℃/minute
The sintering temperature retention time 4 hours
Furnace pressure 100Pa
The mother metal revolution 5 rev/mins
In this stage; The inside that porous layer 205A and atmosphere gas are on every side physically isolated has the translucent glass layer 205B of translucent glass state of the separated foam of vacuum in fact; The average density of part that is in the translucent glass state is the density (2.2g/cm that is in the material of pellucidity according to above-mentioned algorithm calculations result 3) 95% (2.1g/cm 3).
After the wire drawing; The leading section of the translucent glass mother metal of the semi-sintered condition of making like this that contains plug is inserted in the heating furnace shown in Figure 35 30 heat-treats; From carry out clear glassization apart from the about 150mm of mother metal front end that contains tapered portion and parallel portion; With the fusion of mother metal front end, remove the front end processing of unwanted tapering part again.Figure 35 illustrates when with heating furnace the wire drawing of translucent glass layer being begun the leading section clear glassization of side, through fusing, forms the drawing of the state of front end tapered portion 205E.The mother metal diameter of the part of clear glassization is 170mm, and translucent mother metal directly is 173mm.Heat-treat condition is shown in following.
Table 28 transparence condition
Project Condition
Heter temperature when mother metal inserts 1400℃
Heter temperature during transparence 1600℃
Programming rate 5 ℃/minute
The transparence temperature hold-time 1 hour
The front end processing conditions
Project Condition
Heter temperature 2150℃
Programming rate 20 ℃/minute
Front end process time 30 minutes
Even in the present embodiment; Because mother metal wire drawing final end also can not accomplished sintering sometimes, therefore, as appending operation; Preferably carry out thermal treatment, accomplish the sintering processes on surface at least fully through inflammable gas flame such as electric furnace or hydrogen-oxygen, methane or flame passes heating.In addition, also can be through accomplish the sintering on surface equally fully at the dehydrothermal stove 221 shown in Figure 32 with special well heater 223A, 223B.
The fibre parent material of a part of clear glassization of front end tapered portion of making like this and parallel portion is arranged on carries out wire drawing in the fiber drawing furnace shown in Figure 34 240.At this moment, the length of front end hyalomere (being positioned at the length from the mother metal front end to the part that is in the translucent glass state at well heater 243 centers when wire drawing begins) L1 is set to than short to the length L that prolongs tube 248 upper ends 2 from well heater 243 centers.
In the present embodiment, be 80g at the stove core barrel of fiber drawing furnace 240 tension force during directly for 200mm, wire drawing, the furnace temperature when linear velocity is 1500m/min, wire drawing is 2200 ℃, when electric power is 50kW, the life-span of 3 months life-spans of stove core barrel, well heater is 1 year.In addition, in embodiment 17, begin to need 2 hours from wire-drawing operation, but in the present embodiment, begin just can obtain high-quality product, can significantly be improved to bad fiber lengths and loss time that wire drawing begins with 30 minutes from wire-drawing operation to obtaining high-quality product.
(comparative example 3)
To sinter to the embodiment 17 same parts dehydrations of making at plug periphery formation porous layer becomes the clear glass state, makes the fibre parent material of well-illuminated vitreousness.The fibre parent material insertion that obtains is carried out wire drawing with the embodiment 17 same fiber drawing furnaces that are shown in Figure 34 240.Be 80g at the stove core barrel of fiber drawing furnace 240 tension force during directly for 200mm, wire drawing, the furnace temperature when linear velocity is 1500m/min, wire drawing is 2250 ℃, when electric power is 55kW, the life-span of 1 month life-span of stove core barrel, well heater is 6 months.
To sum up, according to as the described the present invention of explanation, in the power cost that can be when reducing the wire drawing of large-scale optical fiber mother metal and the consumption of fiber drawing furnace parts, the debugging operations that can also carry out wire drawing in the short time.
As previously discussed, fibre parent material that the present invention relates to and manufacturing approach thereof are to use the method that when the large-scale optical fiber mother metal is made, is suitable for.
The embodiment of this instructions record is for illustration of the present invention is described, for various variation, for example, the optical fiber etc. with more complicated index distribution also can be included in scope of the present invention, and this is that those skilled in the art can make much of.

Claims (29)

1. the manufacturing approach of a fibre parent material, this method are to have sandwich layer and around the manufacturing approach of the fibre parent material of the clad of this sandwich layer, it is characterized in that having following operation:
Have above-mentioned sandwich layer and be porous preform layer that the bar-shaped quartzy type glass granules of periphery deposit that comprises the plug of quartzy type glass forms the porous preform layer form operation,
Under reduced pressure, under any one condition at least in 3 kinds of environmental baselines of the atmosphere of the atmosphere of non-active gas and halogen gas, non-active gas and halogen chemical compound gas with the dehydration procedure of above-mentioned porous preform pull-up water,
With above-mentioned porous preform layer after will dewatering under the pressure below the 2000Pa sinter to the sintering circuit that becomes the translucent glass mother metal layer that contains separated foam,
With will contain the above-mentioned translucent glass mother metal layer clear glassization of separated foam in the non-active gas atmosphere beyond the helium and then form the clear glass chemical industry preface of above-mentioned clad,
Above-mentioned dehydration procedure is carrying out below 1300 ℃,
Above-mentioned sintering circuit becomes 1.8g/cm in the average density that makes above-mentioned porous preform layer 3More than, not enough 2.2g/cm 3Condition under carry out.
2. according to the manufacturing approach of the fibre parent material of claim 1 record, it is characterized in that,
The inside of contained above-mentioned separated foam is vacuum in the above-mentioned translucent glass mother metal layer.
3. according to the manufacturing approach of fibre parent material of claim 1 or 2 records, it is characterized in that,
Above-mentioned dehydration procedure and above-mentioned sintering circuit; Carry out through using heating furnace to heat above-mentioned porous preform layer on the whole equably; Described heating furnace is that the stove core barrel that contains quartzy type glass is arranged in the pressure vessel; And be provided with a plurality of well heaters around the above-mentioned stove core barrel and constitute
Clear glass chemical industry preface adopts the heating furnace of the regional type of heating with stove core barrel to carry out, and said stove core barrel is made up of any of quartzy type glass and carbon.
4. optical fiber manufacturing method, this method are to have sandwich layer and around the optical fiber manufacturing method of the clad of this sandwich layer, it is characterized in that having following operation:
Have above-mentioned sandwich layer and be porous preform layer that the bar-shaped quartzy type glass granules of periphery deposit that comprises the plug of quartzy type glass forms the porous preform layer form operation,
Under reduced pressure, under any one condition at least in 3 kinds of environmental baselines of the atmosphere of the atmosphere of non-active gas and halogen gas, non-active gas and halogen chemical compound gas with the dehydration procedure of above-mentioned porous preform pull-up water,
With above-mentioned porous preform layer after will dewatering under the pressure below the 2000Pa sinter to the sintering circuit that becomes the translucent glass of the separated foam that contains vacuum mother metal layer,
Carry out wire drawing with the translucent glass mother metal that will contain above-mentioned plug and above-mentioned translucent glass mother metal layer and make above-mentioned translucent glass mother metal layer become the wire-drawing process of transparent glass layer,
Above-mentioned dehydration procedure is carrying out below 1300 ℃,
Above-mentioned sintering circuit becomes 1.8g/cm in the average density that makes above-mentioned porous preform layer 3More than, not enough 2.2g/cm 3Condition under carry out.
5. methods for optical fiber manufacture, this method are to have sandwich layer and around the optical fiber manufacturing method of the clad of this sandwich layer, it is characterized in that having following operation:
Form the porous preform layer at the quartzy type glass granules of the periphery deposit of mandrel, then above-mentioned mandrel is extracted out from above-mentioned porous preform layer, the production process of the tubular porous plastid of manufacturing tubular porous plastid,
Under reduced pressure, under any one condition at least in 3 kinds of environmental baselines of the atmosphere of the atmosphere of non-active gas and halogen gas and non-active gas and halogen chemical compound gas, with the dehydration procedure of above-mentioned tubular porous plastid dehydration,
With will dewater after above-mentioned tubular porous plastid under the pressure below the 2000Pa, sinter to the sintering circuit that becomes the translucent glass cylinder that contains separated foam,
With will have above-mentioned sandwich layer and be the bar-shaped plug that comprises quartzy type glass insert plug in the above-mentioned translucent glass cylinder insert operation,
With the limit the above-mentioned translucent glass cylinder that has inserted above-mentioned plug is heated; The limit wire drawing makes above-mentioned plug and the fusion of above-mentioned translucent glass cylinder is integrated and make above-mentioned translucent glass cylinder become the wire-drawing process of the above-mentioned clad that is made up of clear glass
Above-mentioned dehydration procedure is carrying out below 1300 ℃,
Above-mentioned sintering circuit becomes 1.8g/cm in the average density that makes above-mentioned porous preform layer 3More than, not enough 2.2g/cm 3Condition under carry out.
6. according to the optical fiber manufacturing method of claim 5 record, it is characterized in that,
The inside of contained above-mentioned separated foam is vacuum in the above-mentioned translucent glass cylinder.
7. according to the optical fiber manufacturing method of claim 5 record, it is characterized in that,
Above-mentioned dehydration procedure and above-mentioned sintering circuit; Carry out through using heating furnace to heat above-mentioned porous preform layer on the whole equably, said heating furnace is arranged on the stove core barrel that contains quartzy type glass in the pressure vessel and around above-mentioned stove core barrel, is provided with a plurality of well heaters and constitutes.
8. according to the optical fiber manufacturing method of claim 5 record, it is characterized in that,
Insert between operation and the above-mentioned wire-drawing process at above-mentioned plug, the end heating and melting with the wire-drawing direction side of the above-mentioned translucent glass cylinder that has inserted above-mentioned plug makes its being integrally formed state.
9. the optical fiber manufacturing method of putting down in writing according to claim 8; It is characterized in that; As the wire-drawing direction side end of the above-mentioned translucent glass cylinder that will insert above-mentioned plug heating means during heating and melting in advance, use the injection and in the electric furnace type of heating any one of injection, the flame passes of the inflammable gas flame of hydrogen-oxygen or methane.
10. according to the optical fiber manufacturing method of claim 5 record, it is characterized in that,
In above-mentioned wire-drawing process, between above-mentioned plug of major general and above-mentioned translucent glass cylinder, be set to decompression state.
11. an optical fiber manufacturing method, this method are the optical fiber manufacturing method with sandwich layer more than 1 layer and the clad more than 1 layer that surrounds this sandwich layer, it is characterized in that having following operation:
The periphery deposited glass particulate that has above-mentioned sandwich layer and be bar-shaped plug form the porous preform layer with the 1st prefabrication production process of processing the 1st prefabrication,
With above-mentioned the 1st prefabrication is carried out processed and sintering processes up to the porous preform layer become the translucent glass mother metal layer that contains separated foam the dehydration sintering circuit,
With above-mentioned the 1st prefabrication that will carry out above-mentioned processed and above-mentioned sintering processes insert in the glass tube with the 2nd prefabrication production process of processing the 2nd prefabrication,
With the limit above-mentioned the 2nd prefabrication is heated, the limit wire drawing makes above-mentioned translucent glass mother metal layer and above-mentioned glass tube fusion is integrated and make above-mentioned translucent glass mother metal layer become the wire-drawing process of the above-mentioned clad that is made up of clear glass,
In above-mentioned dehydration sintering circuit, above-mentioned processed and sintering processes are carried out simultaneously,
Above-mentioned dehydration sintering circuit the atmosphere gas that contains non-active gas and halogen gas and contain non-active gas and the atmosphere gas of halogen chemical compound gas at least a atmosphere gas under carry out,
Temperature during processing is more than 1250 ℃, below 1350 ℃,
The average density of above-mentioned translucent glass mother metal layer is 1.8g/cm 3More than, 2.15g/cm 3Below.
12. the optical fiber manufacturing method according to claim 11 record is characterized in that,
Above-mentioned non-active gas is a helium.
13. the optical fiber manufacturing method according to claim 11 record is characterized in that,
Above-mentioned halogen gas is a chlorine.
14. the optical fiber manufacturing method according to claim 11 record is characterized in that,
Above-mentioned halogen compound be in chlorine compound and the fluorine compounds at least any.
15. the optical fiber manufacturing method according to claim 11 record is characterized in that,
In above-mentioned dehydration sintering circuit, the average density of above-mentioned translucent glass mother metal layer is 2.0g/cm 3More than.
16. the optical fiber manufacturing method according to claim 11 record is characterized in that,
In above-mentioned the 2nd prefabrication production process, when inserting above-mentioned the 1st prefabrication in the above-mentioned glass tube, be that the state of vertical direction carries out to keep above-mentioned glass tube.
17. the optical fiber manufacturing method according to claim 11 record is characterized in that,
In above-mentioned the 2nd prefabrication production process, when inserting above-mentioned the 1st prefabrication in the above-mentioned glass tube, be that the state of horizontal direction carries out to keep above-mentioned glass tube.
18. the optical fiber manufacturing method according to claim 11 record is characterized in that,
Between above-mentioned the 2nd prefabrication production process and above-mentioned wire-drawing process, the end heating and melting with the wire-drawing direction side of above-mentioned the 2nd prefabrication makes its being integrally formed state.
19. the optical fiber manufacturing method according to claim 18 record is characterized in that,
Heating means during as the end of the wire-drawing direction side of above-mentioned the 2nd prefabrication of heating and melting are in advance used the injection and in the electric furnace type of heating any of injection, the flame passes of oxyhydrogen flame.
20. the optical fiber manufacturing method according to claim 11 record is characterized in that,
In above-mentioned the 2nd prefabrication production process, be inserted in the above-mentioned glass tube before, the wire drawing with above-mentioned glass tube in advance begins the side heating and melting, forms closed state.
21. the optical fiber manufacturing method according to claim 11 record is characterized in that,
The sealing of above-mentioned glass tube is carried out through above-mentioned glass tube is added thermal cut.
22. the optical fiber manufacturing method according to claim 11 record is characterized in that,
In above-mentioned wire-drawing process, between major general's above-mentioned translucent glass mother metal layer and above-mentioned glass tube, be set to decompression state.
23. the optical fiber manufacturing method according to claim 11 record is characterized in that,
It is below the 1ppm that above-mentioned glass tube contains through chemical reaction synthetic quartzy type glass and hydroxyl OH content.
24. the optical fiber manufacturing method according to claim 23 record is characterized in that,
Above-mentioned glass tube contains fluorine.
25. the optical fiber manufacturing method according to claim 11 record is characterized in that,
Above-mentioned glass tube is 1 glass tube.
26. the optical fiber manufacturing method according to claim 11 record is characterized in that,
Above-mentioned glass tube is to be a plurality of glass tubes of concentric circles with respect to length direction axle lamination.
27. the optical fiber manufacturing method according to claim 26 record is characterized in that,
The limit is carried out the wire drawing limit to above-mentioned translucent glass mother metal layer and above-mentioned a plurality of glass tube and is formed fusion when integrated, with all being set to decompression state between above-mentioned translucent glass mother metal layer and the above-mentioned glass tube and between 2 adjacent glass tubes.
28. the optical fiber manufacturing method according to claim 26 record is characterized in that,
The glass tube that above-mentioned glass tube comprises fluorine-containing glass tube and is made up of pure silica glass, and use the above-mentioned glass tube that constitutes by pure silica glass at outermost layer at least.
29. the optical fiber manufacturing method according to claim 11 record is characterized in that,
To the direction throw light of above-mentioned optical fiber from reporting to the leadship after accomplishing a task; The forward scattering light from above-mentioned fibre scattering is accepted with image sensor in the place ahead in above-mentioned light working direction; Handle its output with signal processing part; Obtain the scattered light intensity distribution patterns, judge in the above-mentioned optical fiber from this scattered light intensity distribution patterns to have or not bubble.
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