CN1740108A - Method for producing optical fiber substrate - Google Patents
Method for producing optical fiber substrate Download PDFInfo
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- CN1740108A CN1740108A CN 200510092768 CN200510092768A CN1740108A CN 1740108 A CN1740108 A CN 1740108A CN 200510092768 CN200510092768 CN 200510092768 CN 200510092768 A CN200510092768 A CN 200510092768A CN 1740108 A CN1740108 A CN 1740108A
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- optical fiber
- core barrel
- temperature
- stove core
- base material
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01486—Means for supporting, rotating or translating the preforms being formed, e.g. lathes
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
- C03B37/0146—Furnaces therefor, e.g. muffle tubes, furnace linings
Abstract
To provide a method for producing an optical fiber preform where the deformation of a support rod or bar supporting a porous preform for an optical fiber is reduced when dehydrated and vitrified to be transparent, where the effective length of the optical fiber preform can be lengthened and where the optical fiber with small eccentricity of a core and small non-circularity of clad can be obtained. The optical fiber preform is produced by the method that the porous preform for the optical fiber whose upper edge is supported with a supporting bar 6 is inserted in a core tube 5 at a heating furnace, dehydrated and vitrified to be transparent. When the maximum temperature in the furnace is set to 1,500[deg.]C at the longitudinal center axis of the core tube 5, the temperature difference in a same face at a circumferential direction in the position of the core tube 5 where the temperature of the longitudinal center axis of the core tube 5 is 1,000-1,300[deg.]C is 10[deg.]C or lower.
Description
Technical field
The present invention relates to manufacture method for the optical fiber base material of the little optical fiber of the non-round rate of optical fiber, particularly core offset and covering that obtains in optical communication etc., using.
Background technology
Existing, make the transparent glass change optical fiber base material the time, be to adopt slowly being inserted in the process furnace with stove core barrel with porous substrate by VAD method and OVD method synthetic optical fiber, dewater, the method for transparent glassization.
In recent years, particularly reduce cost the tendency that the handlebar optical fiber base material maximizes in order to seek.
But maximization along with optical fiber base material, the problem that exists is: supporting optical fiber is with the supporting rod of the silica glass system of porous substrate upper end and the further lower end of the support rod of the silica glass system of this supporting rod of supporting, and thermal distortion such as attenuated by the weight of the optical fiber base material that hangs.
Below, specifically represent process furnace, i.e. the manufacturing installation of optical fiber base material.
As shown in figure 12, covering with dust 2 be deposited in the glass stick 1 that comprises core (below be called plug 1) around form the optical fiber porous substrate, by the supporting rod 4a of silica glass system optical fiber is bearing in porous substrate on the lower end of support rod 6 of silica glass system, make it center on the axle rotation of support rod 6 on one side, in the stove core barrel 5 that possesses well heater 7, send on one side, by well heater 7 heating dewater, transparent glassization, obtain transparent optical fiber base material 8.
Among Figure 12, symbol 3 expression dust 2 by vitrifying part, symbol 4b represents to be connected optical fiber with the supporting rod on the porous substrate the other end, symbol 9 expressions cover the process furnace protective that for example is made of lagging material of well heaters 7 and stove core barrel 5.
As shown in the drawing, on the top of well heater 7, if the process furnace protective 9 that is made of lagging material of whole stove core barrel 5 covers, its temperature distribution substantially then, such wide temperature distribution is represented on the right side that becomes Figure 12 well heater 7 easily.
Like this, it is wide that optical fiber is exposed to high-temperature area with porous substrate, be in the wide temperature distribution time, then optical fiber is connected the supporting rod 4a of the silica glass system on the support rod 6 with porous substrate, also just be exposed to for a long time in the high temperature, as previously mentioned, the problem that is attenuated by the weight of optical fiber base material 8 or the like is arranged.
Usually, this supporting rod 4a uses repeatedly, but if distortion as described above is arranged, then just can not use later.
And if optical fiber is exposed in described such wide temperature distribution with porous substrate, then the difference of carrying out speed of the transparent glassization of its surface and inside becomes big, original hope is such shown in Figure 13 (a), the cone length L on optical fiber base material 8 tops after the transparent glassization
1Be short, but become shown in Figure 13 (b) like that than L
1Long L
2, the problem that exists the promptly actual length that can use of useful length of optical fiber base material 8 to shorten becomes and is difficult to the situation of seeking to reduce cost.
The useful length of optical fiber base material 8, the outer diameter D that is meant base material stable part in the scope of prescribed value, the outer diameter D of promptly having removed optical fiber base material 8 two end portions is certain parts, the optical fiber that can use can the wire drawing part length.
So, for example for the problem of the supporting rod that solves the former, in patent documentation 1 motion at optical fiber with in the transparent glass chemical industry preface of porous substrate, can adjust the process furnace of heater length.
Disclosed in this patent documentation 1, be exactly specifically, carry out optical fiber with the transparent glassization of porous substrate, and during the close well heater of at an upper portion thereof and linking part silica glass system supporting rod, the part on well heater top is removed, make supporting rod not by excessive heat.
Patent documentation 1: the spy opens flat 06-048760 communique
Be that if supporting rod then will according to circumstances must disassemble the part of well heater when arriving prescribed position, its operation is miscellaneous but patent documentation 1 is described.If it is carried out automatically, then there is device to complicate and problem of ultra-high price, be opposite with reducing cost.
So attempted only the part of Figure 12 process furnace protective 9, be exactly that its whole circumferentially going up is removed near the part on the well heater 7 specifically, utilize outside atmosphere to come cool furnace core barrel 5, the method for the rising part steepening of high-temperature area.
According to this method, because the riser portions steepening of temperature in the stove, so shortened heat-up time to supporting rod 4a, the thermal distortion problem of supporting rod 4a is also roughly solved.And optical fiber also diminishes with the difference of the inside and outside vitrifying speed of porous substrate, and the cone on optical fiber base material 8 tops also can reliably obtain such shape shown in Figure 13 (a) after vitrifying.Can more reliably obtain the long optical fiber base material 8 of useful length.
And think this method, only the part of process furnace protective 9 remove just can, so be dog-cheap method, putting on reducing cost from this also is good method.
But when the optical fiber base material 8 that obtains comes wire drawing optical fiber; recognize the core offset and the non-round rate of covering of this optical fiber, remove the optical fiber base material 8 that obtains before the part of process furnace protective 9 than use and come the core offset of the optical fiber that wire drawing obtains and the non-round rate of covering to become big.
Summary of the invention
In view of the above problems, the object of the present invention is to provide a kind of manufacture method of optical fiber base material, its optical fiber with porous substrate dewater, during transparent glass, reduce this optical fiber of the supporting supporting rod of porous substrate and the distortion of support rod, and can also get length to the useful length of optical fiber base material, and can obtain core offset and the little optical fiber of the non-round rate of covering.
In order to reach described purpose, the manufacture method of scheme 1 described optical fiber base material is, the upper end is inserted into porous substrate by the optical fiber of support rod supporting in the described stove core barrel of process furnace and dewaters with stove core barrel, transparent glassization, in the top temperature that makes described stove core barrel length central axis is that 1500 ℃ of ground are when setting the temperature of process furnace, the temperature that makes stove core barrel length central shaft is 1300 ℃ position, be positioned at from the temperature of stove core barrel length central shaft be 1400 ℃ position in the axial top 300mm of stove core barrel, and to make the temperature of stove core barrel length central shaft be to be less than or equal to 10 ℃ with the temperature head in the one side circumferentially in the stove core barrel of 1000～1300 ℃ of positions.
Manufacture method according to this scheme 1 described optical fiber base material, because in the top temperature of described stove core barrel length central shaft is that 1500 ℃ of ground are when setting the temperature of process furnace, the temperature that makes stove core barrel length central shaft is 1300 ℃ position, being positioned at from the temperature of stove core barrel length central shaft is that 1400 ℃ position is in the axial top 300mm of stove core barrel, promptly to the temperature distribution steepening of the rising part of high-temperature portion, so, can reduce supporting the optical fiber supporting rod of porous substrate and the distortion of support rod more reliably, and can also get length to the useful length of optical fiber base material, can seek to reduce the cost of optical fiber.
Simultaneously because to make the temperature of stove core barrel length central shaft be to be to be less than or equal to 10 ℃ with the temperature head in the one side circumferentially in the stove core barrel of 1000～1300 ℃ of positions, so, optical fiber from the upwards roughly uniform temperature heating of quilt of its week, consequently can be made the little optical fiber base material of the non-round rate of core offset and covering with porous substrate easily.Therefore, if when this optical fiber base material carried out wire drawing, then can obtain the little optical fiber of the non-round rate of core offset and covering.
The manufacture method of scheme 2 described optical fiber base materials is in the manufacture method of scheme 1 described optical fiber base material, is the periphery of the stove core barrel in 1000～1300 ℃ of zones in the temperature of described stove core barrel length central axis, and the ablative shielding thing is set.
Manufacture method according to this scheme 2 described optical fiber base materials, because the temperature in stove core barrel length central axis is the periphery of the stove core barrel in 1000～1300 ℃ of zones, be provided with the ablative shielding thing, so, can be more reliably the temperature distribution steepening in 1000～1300 ℃ of zones of stove core barrel, and the eliminating externalities makes the circumferential temperature distribution of stove core barrel more even, can keep being less than or equal to 10 ℃ temperature head specifically exactly.
Therefore, can reduce the distortion of supporting rod and support rod certainly, can also get length to the useful length of optical fiber base material, when carrying out wire drawing, then can also obtain the very little optical fiber of the non-round rate of core offset and covering as if an optical fiber base material of making.
According to above the present invention, a kind of manufacture method of optical fiber base material just can be provided, its optical fiber with porous substrate dewater, during transparent glass, reduce this optical fiber of the supporting supporting rod of porous substrate and the distortion of support rod, and can also get length to the useful length of optical fiber base material, and can obtain core offset and the little optical fiber of the non-round rate of covering.
Description of drawings
Fig. 1 is the sketch chart of the optical fiber base material manufacturing installation of the expression embodiment of the invention 1 use;
Fig. 2 is the graphic representation of circumferential maximum temperature difference of expression stove core barrel and fiber cores offset mean value relation;
Fig. 3 is the graphic representation of its length direction core offset change of optical fiber of being obtained by embodiment 1 of expression;
Fig. 4 is a graphic representation of representing the non-round rate change of its length direction covering of optical fiber that is obtained by embodiment 1;
Fig. 5 is the sketch chart of the optical fiber base material manufacturing installation of the expression embodiment of the invention 2 uses;
Fig. 6 is the graphic representation of its length direction core offset change of optical fiber of being obtained by embodiment 2 of expression;
Fig. 7 is a graphic representation of representing the non-round rate change of its length direction covering of optical fiber that is obtained by embodiment 2;
Fig. 8 is the sketch chart of the optical fiber base material manufacturing installation of expression comparative example 1 use;
Fig. 9 is the graphic representation of its length direction core offset change of optical fiber of being obtained by comparative example 1 of expression;
Figure 10 is a graphic representation of representing the non-round rate change of its length direction covering of optical fiber that is obtained by comparative example 1;
Figure 11 is the sketch chart of the optical fiber base material manufacturing installation of expression comparative example 2 uses;
Figure 12 is the sketch chart of existing optical fiber base material manufacturing installation;
Figure 13 is the amplification longitudinal diagram of expression optical fiber base material leading section shape, (a) is the amplification profile of the long optical fiber base material of useful length, (b) is the amplification profile of the short optical fiber base material of useful length.
Embodiment
Below describe the manufacture method of optical fiber base material of the present invention in detail with figure.On the part identical, pay identical symbol, and omit its detailed description with existing optical fiber base material manufacturing installation shown in Figure 12.
Fig. 1 is the sketch chart of the optical fiber base material manufacturing installation that uses among the embodiment of optical fiber base material manufacture method of the present invention, and Fig. 5 is the sketch chart of the manufacturing installation that uses in other embodiments.
The manufacturing kind of embodiment and comparative example is the most general single-mode fiber in this specification sheets.
[embodiment 1]
As shown in Figure 1, covering is being deposited in the two ends of the optical fiber that forms of plug 1 with porous substrate on every side with dust 2, be connected with supporting rod 4a, the 4b of silica glass system respectively, the optical fiber porous substrate is connected by this supporting rod 4a on the support rod 6 of silica glass system.And supporting rod 4a and support rod 6 for example are fixedly to come banded by pin.
As previously mentioned, be installed in optical fiber on the front end of support rod 6 by supporting rod 4a with porous substrate, it is rotated around the axle of support rod 6 on one side, in the stove core barrel 5 that possesses well heater 7, send on one side, carry out thermal dehydration and carry out transparent glassization and obtain transparent optical fiber base material 8 with the speed of regulation.Make the axle center of described support rod 6 consistent with the length central shaft of described stove core barrel 5.
The manufacturing installation of this embodiment 1 employed optical fiber base material is that the characteristics of process furnace are; as shown in Figure 1; the process furnace protective 9 that covers stove core barrel 5 and well heater 7 is removed; and near the part on the well heater 7, ablative shielding thing 10 be provided with the length central shaft of stove core barrel 5 be on the point of coaxial shape.
This ablative shielding thing 10 is that aluminium sheet is installed in its inboard as heating panel, consider operator's safety and the ring of lagging material is arranged in its arranged outside, its with stove core barrel 5 coaxial shapes be arranged on the outside of stove core barrel 5, and be the state that is provided with the 150mm gap with stove core barrel 5 in this example.
At this, the reason that ablative shielding thing 10 is arranged near the part place on the well heater 7 is as previously mentioned: handle covers near the stove core barrel on the well heater 75 by ablative shielding thing 10 is set, when getting rid of external environment influence, utilize the thermal diffusivity of this ablative shielding thing 10 that a part of temperature of stove core barrel 5 is dispelled the heat to the outside, make in the temperature distribution that produces by well heater 7 rising steepening to high-temperature portion.
Among Fig. 1, shown in the temperature distribution history of its right side record, when the temperature distribution of representing with dotted line among the figure along the stove core barrel 5 length central shafts of Figure 12 process furnace compared, the temperature distribution of Fig. 1 process furnace (solid line is represented) was steep to the rising of high-temperature portion.
Promptly; inventor of the present invention infers; as previously mentioned Figure 12 is upwards removed in its whole week near the process furnace protective 9 on the well heater 7; utilize outside atmosphere to come cool furnace core barrel 5; the result who carries out to the trial of the rising part steepening of high-temperature area; why the non-round rate of the core offset of optical fiber and covering is bigger than using the core offset and the non-round rate of covering of removing the optical fiber that obtains before the process furnace protective 9; be to be exposed to stove core barrel 5 in the outside atmosphere owing to having removed process furnace protective 9, by the influence of outside atmosphere week upwards by inhomogeneous refrigerative cause.So be provided with this ablative shielding thing 10 according to covering outer atmosphere and cool furnace core barrel 5 these two purposes.
For concrete proof this point, to stove core barrel 5 near part on the well heater 7, dry etc. stove core barrel 5 circumferential outside atmospheres are changed unevenly, making temperature on the stove core barrel length central shaft is the circumferential temperature variation of stove core barrel 5 of about 1250 ℃ of positions, investigates the relation of circumferential maximum temperature difference and fiber cores offset mean value.
Its result is illustrated in Fig. 2.As shown in Figure 2, with the circumferential temperature head of stove core barrel 5 pro rata the mean value of core offset also become greatly, the supposition of recognizing the present inventor is correct.Recognize that particularly circumferential maximum temperature difference is if surpassed 10 ℃, then the mean value of core offset has the big tendency of rapid change, need be circumferential maximum temperature difference position for being less than or equal to 10 ℃.
Needing circumferential maximum temperature difference is that to be less than or equal to 10 ℃ position be that the temperature of stove core barrel length central shaft is 1000～1300 ℃ zone.General people know that the temperature that dust begins to shrink is 1000～1300 ℃.If big in the circumferential maximum temperature difference of this temperature province stove core barrel, then dust just carries out asymmetric contraction, and as a result of, it becomes the reason of making the big optical fiber base material of core offset and the non-round rate of covering.
At this, the core offset of optical fiber and the definition of the non-round rate of covering are as the criterion with IEC60793-1-20.
At this set under the state of ablative shielding thing 10, the top temperature that the temperature of process furnace is set at stove core barrel 5 centers becomes necessary 1500 ℃ of dust 2 transparent glassizationes, and in stove core barrel 5 He is carried out 10 liters/shunting with meeting dust 2 transparent glass conditions.Under this state, insert thermopair along the length central shaft of stove core barrel 5 from top, carry out the measurement of temperature in the stove.
During measurement, at first the length central shaft of thermopair along stove core barrel 5 inserted, on the length direction of stove core barrel 5 with every 50mm move, the temperature of measurement is to survey about 1000 ℃～1300 ℃ zone, measures circumferential temperature head in the stove core barrel 5 afterwards in this zone.Be exactly specifically, the measuring position is set in the position of leaving 20mm from the inwall of stove core barrel 5, thermopair is measured with the 45 ° of ground that upwards respectively stagger in week, promptly on circumferential same plane, carry out 8 point measurements in each position.This result is that maximum temperature difference is 8 ° in the stove core barrel 5 of embodiment 1.
Use this manufacturing installation, carry out dehydration, the transparent glassization of optical fiber practically with porous substrate.As this optical fiber porous substrate, use be as on the plug 1 that covering utilizes the dust 2 of external diameter 280mm known OVD method to be attached in advance outside to dewater, transparent glassization is over.This optical fiber is sent in the stove core barrel 5 of internal diameter 320mm while rotating with certain speed with porous substrate, dewaters, transparent glassization, make optical fiber base material 8.
Finish getting useful length on the long optical fiber base material as Figure 13 (a) the upper end of the optical fiber base material 8 that obtains.
Its core offset of optical fiber measurement that obtains this optical fiber base material 8 is carried out wire drawing and the result of the non-round rate of covering are, the mean value of core offset is 0.11 μ m, the mean value of the non-round rate of covering is 0.09%, and standard deviation separately is respectively 0.01 μ m and 0.01%.
In the lower end of supporting rod 4a and support rod 6, do not find any distortion and damage.
Among this embodiment 1, when the top temperature at stove core barrel 5 centers was adjusted to 1500 ℃, the temperature at stove core barrel 5 centers was that 1300 ℃ position is the 190mm position above 1400 ℃ of positions.
Each change of the core offset of this fiber length and the non-round rate of covering is indicated on Fig. 3 and Fig. 4.Recognize that from these figure the optical fiber that obtains is qualitatively without any problem.At this, among two figure, transverse axis is represented fiber lengths, and the left side is a supporting rod 4a side, and the right side is a supporting rod 4b side.
[embodiment 2]
Use Fig. 5 to represent other embodiment of the present invention.This ablative shielding thing 10 similarly is arranged to Fig. 1, when the top temperature of stove core barrel 5 length central shafts is 1500 ℃, in the temperature of stove core barrel 5 length central shafts is that 1000 ℃～1300 ℃ zone surrounds stove core barrel 5, as shown in Figure 5, its shape is the cake-shaped case shape of the tower shape hollow that is opened of stove core barrel 5 sides.This ablative shielding thing 10 is pasted with the aluminium of fine heat radiation property in the case inboard of lagging material system.
Be exactly specifically, this ablative shielding thing 10 has the about 3 times external diameter of stove core barrel 5 external diameters, and its internal diameter is bigger a little than the external diameter of stove core barrel 5, makes both gaps very little.
Like this, near well heater 7,, and also be formed with the space between the stove core barrel 5, so just can seek suitable heat radiation, and can become stove core barrel 5 circumferential temperature evenly in 1000 ℃～1300 ℃ zone in stove core barrel 5 outer side covers.
Temperature is less than or equal to 1000 ℃ zone in the stove of ablative shielding thing 10 tops, also can be to keep the state of opening, and also can implement process furnace protective 9 as existing.
This embodiment 2 also is identified similarly to Example 1: the result who measures 1000 ℃～1300 ℃ of circumferential temperature in zone is that maximum temperature difference is 6 ℃.
Among Fig. 5, shown in the temperature distribution history of its right side record, when the temperature distribution of Figure 12 process furnace of representing with dotted line among the figure compared, the temperature distribution of Fig. 5 process furnace (solid line is represented) was steep to the rising of high-temperature portion.And the temperature of length central shaft is that 1300 ℃ position is the 210mm position above 1400 ℃ point in the stove core barrel 5.
Utilize the manufacturing installation of optical fiber base material shown in Figure 5, with the optical fiber of embodiment 1 same size with porous substrate dewater, transparent glassization, obtain optical fiber base material 8.The top of this optical fiber base material 8 is done as Figure 13 (a) similarly to Example 1.
Its core offset of optical fiber measurement that obtains this optical fiber base material 8 that obtains is carried out wire drawing and the result of the non-round rate of covering are, the mean value of core offset is 0.08 μ m, the mean value of the non-round rate of covering is 0.07%, and standard deviation is respectively 0.01 μ m and 0.01%.
In the lower end of supporting rod 4a and support rod 6, the distortion of discovery etc. among this embodiment 2 yet.
Each change of the core offset of this fiber length and the non-round rate of covering is indicated on Fig. 6 and Fig. 7.Recognize from these figure, the non-round rate of core offset and covering all optical fiber qualitatively without any problem.At this, in these figure, transverse axis is represented fiber lengths, and the left side is a supporting rod 4a side, and the right side is a supporting rod 4b side.
[comparative example 1]
Below represent comparative example 1.The manufacturing installation of optical fiber base material shown in Figure 8 except from manufacturing installation shown in Figure 1 ablative shielding thing 10 being removed, is identical device.With embodiment 1 in the identical optical fiber porous substrate that uses, be sent in the stove core barrel 5 of this optical fiber base material manufacturing installation with the condition identical with embodiment 1, dewater, transparent glassization, obtain its upper end such optical fiber base material 8 shown in Figure 13 (a).
Its core offset of optical fiber measurement that obtains this optical fiber base material 8 is carried out wire drawing and the result of the non-round rate of covering are, the mean value of core offset is 0.20 μ m, the mean value of the non-round rate of covering is 0.13%, and standard deviation separately is respectively 0.03 μ m and 0.02%.
Each change of the core offset of this fiber length and the non-round rate of covering is indicated among Fig. 9 and Figure 10.
Among two figure, transverse axis is represented fiber lengths, and the left side is a supporting rod 4a side, and the right side is a supporting rod 4b side.As Fig. 9 and shown in Figure 10, the non-round rate of core offset and covering all on the length direction of optical fiber to supporting rod 4b side and its value becomes big.
And in this comparative example 1, shown in the temperature distribution history of Fig. 8 right side record, when the temperature distribution of Figure 12 process furnace of representing with dotted line among the figure compares, the temperature distribution of Fig. 8 process furnace (solid line is represented) is steep to the rising of high-temperature portion, and when the top temperature of stove core barrel 5 length central shafts was 1500 ℃, the temperature of stove core barrel 5 length central shafts was 150mm positions above 1400 ℃ of positions, position of 1300 ℃.
With described each embodiment similarly, in the temperature of stove core barrel 5 length central shafts temperature provinces of 1000 ℃～1300 ℃, leave the position of 20mm at inwall from stove core barrel 5, at grade thermopair is moved the temperature survey of carrying out 8 positions on the 45 ° of ground that upwards stagger in week, consequently observe, maximum temperature difference is that the temperature at stove core barrel length central shaft is about 1250 ℃ position, and its value is 15 °.
The result thinks, owing to do not have ablative shielding thing 10 in this comparative example 1, so in the temperature of stove core barrel 5 length central shafts was 1000 ℃～1300 ℃ temperature province, the circumferential temperature head of stove core barrel 5 was big, the non-round rate of core offset and covering is big.
[comparative example 2]
The comparative example of representing other below.What Figure 11 represented is the manufacturing installation of the optical fiber base material of comparative example 2 uses, it is process furnace, the characteristics of this process furnace are: when the top temperature of stove core barrel 5 length central shafts is 1500 ℃, be in 1000 ℃～1300 ℃ the zone and shield 11 be set in the temperature of stove core barrel 5 length central shafts near the part on the well heater 7, so that stove core barrel 5 is surrounded, this shield 11 only is made of the lagging material of ceramic fiber system.
The temperature of length central shaft is 1000 ℃～1300 ℃ zone in the stove core barrel 5 of this manufacturing installation, similarly measures the circumferential temperature of stove core barrel 5 with embodiment 1,2 and comparative example 1, consequently confirms the maximum temperature head that has 2 ℃.
Shown in the temperature distribution history of Figure 11 right side record, the temperature distribution of Figure 11 process furnace (solid line is represented), the temperature distribution of Figure 12 process furnace of representing with dotted line is roughly the same, and the temperature of length central shaft is that 1300 ℃ position is 330mm position above 1400 ℃ point in the stove core barrel.
Use this process furnace,, obtain optical fiber base material 8 similarly being sent in the stove core barrel 5 with porous substrate with the same optical fiber of embodiment 1,2 and comparative example 1.The cone on these optical fiber base material 8 tops is long like that shown in the L2 of Figure 13 (b).
The optical fiber base material 8 that obtains is carried out wire drawing and obtains optical fiber, and the mean value of its core offset is 0.08 μ m, and the mean value of the non-round rate of covering is 0.07%, and standard deviation is respectively 0.01 μ m and 0.01%.
Measured the core offset of this fiber length and the change of the non-round rate of covering, be and Fig. 6 and the roughly the same result of Fig. 7, be the non-round rate of core offset and covering optical fiber qualitatively all without any the result of problem.
But in this comparative example 2, supporting rod 4a has produced elongation, and has also found partly distortion in the lower end of support rod 6.This consideration is that high-temperature portion is wide temperature distribution on the length central shaft of stove core barrel 5, the temperature that is exactly length central shaft in the stove core barrel 5 specifically is that 1300 ℃ position is 330mm position above 1400 ℃ point, like this, the cause that too heats of the lower end of supporting rod 4a and support rod 6.And the top of optical fiber base material 8 is useful length weak point as Figure 13 (b) also, can not reduce cost.
Comparative example 2 is like this, though the non-round rate mean value of the core offset mean value of optical fiber and covering is to have satisfied on optical fiber quality, but the useful length of optical fiber base material 8 is short, be not suitable for reducing cost, and having found thermal distortion on supporting rod 4a and support rod 6, is to have utilized for supporting rod 4a particularly again.
Among each above-mentioned embodiment, use as ablative shielding thing 10 aluminium on the installed inside of lagging material, but as the thermal diffusivity material, for example copper coin, Copper Foil etc. except aluminium, be good on thermal diffusivity, in other words, so long as the good not combustible matl of thermal conductivity can both use.As lagging material is to use graphite, but in view of the purpose master of this ablative shielding thing 10 if it were not for heat insulation but heat radiation, the thickness of lagging material is set at necessary thickness in operator's usability and security, too not thick is very important.
On near well heater 7, be provided with ablative shielding thing 10; but the part on this ablative shielding thing 10; the temperature that is stove core barrel 5 length central shafts is to be less than or equal to 1000 ℃ part; also can expose stove core barrel 5 motionless, even as existing like that also out of question with 9 coverings of process furnace protective.Neededly be, is the temperature of stove core barrel 5 length central shafts the outside of the stove core barrel 5 of 1000 ℃～1300 ℃ of parts, shown in embodiment 1,2, cover with ablative shielding thing 10 like that, the temperature that makes stove core barrel 5 length central shafts is that 1300 ℃ position is being above 1400 ℃ the position in the 300mm, and the temperature that makes the length central shaft is that the circumferential maximum temperature difference of the stove core barrel 5 of 1000 ℃～1300 ℃ of parts is in 10 ℃.
As previously discussed, the manufacture method of optical fiber base material according to the present invention, a kind of manufacture method of optical fiber base material just can be provided, its optical fiber with porous substrate dewater, during transparent glass, reduce this optical fiber of the supporting supporting rod of porous substrate and the distortion of support rod, and can also get length to the useful length of optical fiber base material, and can obtain core offset and the little optical fiber of the non-round rate of covering.
Claims (2)
1, a kind of manufacture method of optical fiber base material, the upper end is inserted into porous substrate by the optical fiber of support rod supporting in the described stove core barrel of process furnace and dewaters with stove core barrel, transparent glassization, it is characterized in that, in the top temperature that makes described stove core barrel length central axis is that 1500 ℃ of ground are when setting the temperature of process furnace, the temperature that makes stove core barrel length central shaft is 1300 ℃ position, be positioned at from the temperature of stove core barrel length central shaft be 1400 ℃ position in the axial top 300mm of stove core barrel, and the temperature of stove core barrel length central shaft is to be less than or equal to 10 ℃ with the temperature head in the one side circumferentially in the stove core barrel of 1000～1300 ℃ of positions.
2, the manufacture method of optical fiber base material as claimed in claim 1 is characterized in that, is that the periphery of the stove core barrel in 1000～1300 ℃ of zones is provided with the ablative shielding thing in the temperature of described stove core barrel length central shaft.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP241768/04 | 2004-08-23 | ||
| JP2004241768A JP4609839B2 (en) | 2004-08-23 | 2004-08-23 | Optical fiber preform manufacturing method |
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| CN1740108B CN1740108B (en) | 2011-03-23 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105271697A (en) * | 2015-11-03 | 2016-01-27 | 江苏亨通光电股份有限公司 | Sintering furnace |
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| JP5793843B2 (en) * | 2010-10-01 | 2015-10-14 | 住友電気工業株式会社 | Manufacturing method of glass base material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2683757B2 (en) * | 1988-12-15 | 1997-12-03 | 住友電気工業株式会社 | Glass base material support method and support structure thereof |
| JPH0648760A (en) * | 1992-07-30 | 1994-02-22 | Fujikura Ltd | Production of performed material for optical fiber |
| JP3190980B2 (en) * | 1992-08-06 | 2001-07-23 | 日本板硝子株式会社 | Flake glass manufacturing equipment |
| JP3378287B2 (en) * | 1993-02-10 | 2003-02-17 | 株式会社フジクラ | heating furnace |
| JPH06235828A (en) * | 1993-02-10 | 1994-08-23 | Sumitomo Electric Ind Ltd | Heating furnace for drawing optical fiber preform |
| JP2562561B2 (en) * | 1993-12-15 | 1996-12-11 | 古河電気工業株式会社 | Equipment for manufacturing porous preforms for optical fibers |
| JPH0925136A (en) * | 1995-07-14 | 1997-01-28 | Sumitomo Electric Ind Ltd | Optical fiber drawing furnace and drawing method |
| ID26017A (en) * | 1998-04-03 | 2000-11-16 | Sumitomo Electric Industries | TANK AND METHOD FOR WITHDRAWAL OF OPTICAL FIBER CABLE |
| JP2002338259A (en) * | 2001-05-15 | 2002-11-27 | Sumitomo Electric Ind Ltd | Device for heating glass preform and method for controlling the same |
| JP2004091295A (en) * | 2002-09-03 | 2004-03-25 | Furukawa Electric Co Ltd:The | Method of manufacturing optical fiber preform |
| JP2004115289A (en) * | 2002-09-24 | 2004-04-15 | Shin Etsu Chem Co Ltd | Manufacturing process of ingot for optical fiber preform and hanging member used in the process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105271697A (en) * | 2015-11-03 | 2016-01-27 | 江苏亨通光电股份有限公司 | Sintering furnace |
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| Publication number | Publication date |
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| JP4609839B2 (en) | 2011-01-12 |
| CN1740108B (en) | 2011-03-23 |
| JP2006056755A (en) | 2006-03-02 |
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