CN1287103A - Prcess for producing precast blank - Google Patents
Prcess for producing precast blank Download PDFInfo
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- CN1287103A CN1287103A CN 00106544 CN00106544A CN1287103A CN 1287103 A CN1287103 A CN 1287103A CN 00106544 CN00106544 CN 00106544 CN 00106544 A CN00106544 A CN 00106544A CN 1287103 A CN1287103 A CN 1287103A
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- preform
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Abstract
The production process of blank for drawing single-mode photoconductive fiber includes two stages. In the inner deposition stage, quartz layer and doped quartz layer are deposited inside quartz tube, and before the deposition of subsequent layer, the doped quartz layer is cured to minimize the diffusion of dopant. Then, the quartz tube containing the deposited material is heated to contract and form solid stem, and coated with basically homogeneous quartz material via an external deposition process. The coated stem is finally heated to cure and complete the manufacture of the prefabricated blank.
Description
The present invention relates to a kind of method of making a kind of preform, from this preform, can draw single mode optical fibre.The present invention is applied to the manufacturing of preform especially, from this preform, can draw out diffusion drift (comprising the diffusion drift of non-zero) with rear-earth-doped photoconductive fiber, but be understandable that the present invention has very wide application really.
Usually use a kind of manufacturing preform in following two kinds of diverse ways: 1. internalist methodology, comprise modified chemical vapor deposition process (MCVD) (MCVD), plasma-activated chemical Vapor deposition process (PCVD) or if rear-earth-doped preform then has the solute doping method.2. externalist methodology comprises outside chemical Vapor deposition process (OVD) or axial chemical Vapor deposition process (AVD).
The method that is adopted under a specified criteria depends primarily on desired length of the optical fiber of pulling out and characteristic from preform.In this manual content of the present invention will be described.In general external deposition method (OVD or AVD) provides the method more cheap to bigger preform, and inside deposition method (MCVD, PCVD or solute doping) generally is used to make relatively expensive and less preform.
The preform of using the internal law manufacturing has glass bushing sometimes to realize the diameter of final enough big preform, so just can draw out the optical fiber of length.Yet mounting sleeve is a kind of very expensive method in the scope of the technical parameter of the right alignment that meets fibre core, and the sleeve pipe that the external diameter of the optical fiber of pulling out requires to be adorned has very low tolerance on its geometry.
In the preform manufacturing processed by its drawing optical fiber, the single-mode fiber of various special uses has the index of minimum diffuse dopants (specific refractory power) and distributes.
In non-zero type drift diffusion fiber, with respect to the distribution of the fiber of standard, fibre core must have Compound Distribution.Usually, fibre core comprises by many rings with alternately high and low specific refractory power and composite structure that inner region is formed.Design comprises following structure: inner region has high specific refractory power and near ring has the structure of low specific refractory power and inner region has the structure that low specific refractory power and near ring have high specific refractory power.These schemes make drift, spot diameter, bending radius and other characteristic such as optimizations such as nonlinear interactions, to satisfy the application of expection.In preferred design, the central zone of fibre core has higher relatively specific refractory power, and in fibre core, surround the central zone that (promptly " circularizing ") fibre core by ring with lower specific refractory power, and will encircle by an intermediate core zone and to separate, the specific refractory power that the specific refractory power in this intermediate core zone is lower than region intermediate and surrounds ring from the central zone.Ideally, the specific refractory power in intermediate core zone is lower than the specific refractory power of cladding of fiber, this just require to use have higher current potential doping agent (for example, fluorine) between layer, to spread.
In rare earth doped fiber, requirement subtly the deposition of controlled doping agent to obtain having the zone of different dopant concentration.Yet, can recognize in order that if include single settled layer not curing before deposition layer subsequently of doping agent, rare earth ion is tending towards assembling by diffusion.
The present invention is based on such understanding, (OVD or AVD) compares with external deposition method, and inside deposition method (MCVD, PCVD or solute doping) can be controlled at the diffusion of the doping agent between the settled layer effectively.Therefore, the inside deposition method helps control index (specific refractory power) distribution subtly, or if rare-earth doped optical fibre then is convenient to the distribution of controlled doping agent subtly.In addition, the present invention has embodied and has mixed the notion of using inside and outside deposition method.This just makes it possible to make a kind of like this preform, and it has the specific refractory power or the dopant distribution of meticulous control, and than producing routinely by internal law fully telescopic is housed, preform that size is suitable is cheap.
Broadly, the invention provides a kind of method of making preform, from this preform, can draw out single mode optical fibre, this method comprises the steps: a) to use the quartz layer of inside deposition method dopant deposition on the inner face of silica tube, b) before deposition of subsequent layers, solidify each adulterated quartz layer, so that the diffusion minimum of doping agent between layer, c) thermal contraction silica tube and make sedimentary material form the solid plug, d) coat basic quartz material uniformly in the outside of plug by OVD, and e) this covering plug is cured heating to finish the manufacturing of preform.
The present invention can also limit according to preform when the application aforesaid method is produced preform, and the present invention can also limit according to optical fiber when from this preform drawing optical fiber.
The present invention relates to a kind of mixed production method effectively.It has the inter-level diffusion of minimum doping agent in the process that forms the preform core, and allows relative less expensive ground to make larger-diameter preform simultaneously.
By solidifying each adulterated quartz layer, the diffusion of doping agent is limited in separately the layer substantially in the process of using the inside deposition method.Diffusion length (that is, the whole distance that diffusion produces) depends on the voidage of deposition flue dust (soot), and is bigger at first, along with solidified carry out and the given time of layer in high temperature become more and more littler.Therefore, in the process of inside deposition, make diffusion reach minimum by solidifying these settled layers, these settled layers are littler than the diffusion length of the dopant species that occurs in solidification process, and guarantee to realize this goal by solidified each layer before each succeeding layer of deposition.
After every layer of curing, diffusion length is very little, and the influence of the reheat of preform can be ignored subsequently.Therefore, can produce larger-diameter preform economically as mixed structure.For produce even quartzy covering by the sedimentary flue dust of OVD can be in for some time, but divide two step consolidations, may in adulterated quartz layer, cause unacceptable diffusion during this period of time.
In addition, by producing mixed structure, the manufacturing processed in two stages allowed before the deposition extramural cladding fibre core to preform to distribute to carry out opticmeasurement.
Doping agent comprises rare earth dopant (such as erbium and ytterbium), help forming the doping agent (such as aluminium) of higher rare earth element concentration and/or influence the doping agent (such as germanium, lead, boron and fluorine) of the specific refractory power of optical fiber (it draws from preform).
Preferably, use outside gas deposition (OVD) method at the outer bread of plug with quartz.
In addition, preferably, the plug of formation comprises core structure and external region, and this core structure forms the core of the optical fiber that draws from preform, and this external region forms the radial the inside part of fibre cladding.
Can control inner vapor deposition method to form the core structure of any required index distribution.Yet, preferably, control this sedimentation in core structure, to set up three diacritic in theory area on-axis:
Has relative high index n
1The central zone;
Has relatively low refractive index n
2Outer shroud; With
Have the refractive index n lower than the specific refractory power of outer shroud
3Interior ring.
The most preferably, the refractive index n of interior ring
3Be lower than the refractive index n of covering
4Yet as previously pointed out, the preform structure that can adopt other to be making non-zero type diffusion drift optical fiber, such as have specific refractory power be lower than in the preform of central zone of specific refractory power of ring.
In addition, can control inner vapor deposition method and deposit continuous layer of material to provide a kind of fractionated index distribution in the center of core structure, interior ring and/or outer region in a certain mode.
In addition, as mentioned before, the preform structure design can adopt according to their rare earth element or other concentration of dopant has diacritic in theory area on-axis.
From the description of subsequently the preferred embodiments of the present invention, can understand the present invention more fully.This description is carried out in conjunction with the accompanying drawings.
In the accompanying drawings:
Figure 1 shows that the schematic sectional view of expression by a kind of complete preform of method manufacturing of the present invention.
Figure 2 shows that the fs synoptic diagram of expression manufacturing preform.
Fig. 3 and 4 is depicted as the synoptic diagram that is illustrated in applied production process in the subordinate phase of making preform.
Figure 5 shows that the index of refraction diagram in the fibre core that is illustrated in the optical fiber that from preform, draws.
Fig. 6 to 10 is depicted as the optic fibre characteristic that expression is derived from the parameter of the preform of the optical fiber that changes and drawing optical fiber.
With reference to the accompanying drawings, Figure 1 shows that the schematic cross sectional view of expression by a kind of preform of two-phase method manufacturing of the present invention.Yet, be understandable that in different area on-axis shown in Figure 1 and can not draw in proportion.The outside dimension of preform is generally 10 to 15 times magnitude of the core size (being determined by the inner domain) of preform.Shown preform has diacritic in theory area on-axis, this area on-axis is by constituting as the lower section: a core structure 10, is inner cladding part 11, a tundish layer segment 12 and surrounding layer part 13 radially radially, this radially inner cladding part 11 be sedimentary by inner vapor deposition method when forming core structure 10, this tundish layer segment 12 is to form by shrinking silica tube 14 making in the fs of preform, this radially surrounding layer part 13 be sedimentary in the second manufacturing stage process.The different same shaft portion of preform (diacritic in theory) generally has following size.
Diameter (mm)
Core structure (10) 4.60-5.20
Clad section (11) 12.42-14.04
Clad section (12) 21.45-22.42
Clad section (13) 62.10-70.70
As described in Fig. 2, the chemical vapor deposition of improved routine (MCVD) method realized for first manufacturing stage by the settled layer of quartzy and quartzy dopant material in rotation silica tube 14 by being used in varying degrees, shrank silica tube and deposition material then to form solid plug 15.Use plug 15 then as mandrel, in subordinate phase, on this mandrel, deposit clad material, as shown in Figure 3.
In first manufacturing stage, lathe jig 16 supports silica tube 14, and makes it around its rotation.Deliver a vapor to the inside of pipe from chemical delivery system 17, and heat (rotation simultaneously) by the 18 pairs of pipes of thermal source that move around, this thermal source that moves around 18 generally comprises a kind of oxygen-hydrogen torch.19 transfer the fuels are given this blowtorch from the source.
Though do not illustrate in the drawings, the downstream end of silica tube 14 is fused to a large diameter Glass tubing usually, the unspent material of its auto-deposition process that is used for collecting, and the material that do not exhaust of steam state is delivered directly in the exhaust system.
Deposition method can be described as the high temperature vapor phase oxidation of carrier band volatile vapors composition simply, and this carrier band volatile vapors composition deposits with subparticle, and is fused to silica tube 14.Owing to deliver a vapor to pipe 14 from chemical delivery system 17, blowtorch 18 moves along the length of pipe is round, and oxidizing reaction and particulate nucleation have taken place in the inside of pipe.Particulate its band increase during through pipe and the part particulate from the cooling stave in the downstream of the pipe in blowtorch 18 direct-fired zones by the thermophoresis deposition under.In the process of blowtorch 18 each processes, the particulate that before had been deposited on the downstream carries out consolidation through out-of-date by the viscosity sintering at blowtorch.
At first deposit highly purified covering to form radially clad section 11, then the material layer of formation of deposits fibre core 10.The component of control sandwich layer is to form desired index distribution.For this reason, generally use germanium and phosphorus dopant so that specific refractory power is increased to more than the specific refractory power of pure quartz, and fluorine and boron dope agent are used for generally specific refractory power is reduced to below the quartzy specific refractory power.
When manufacturing comprises the preform of rare earth dopant, can mix with rare earth element and other doping agent cored structure 10.These doping agents comprise aluminium and help adding other element of rare earth ion, and the mixture of rare earth ion and rare earth ion.The latter comprises erbium and ytterbium.
The different chemical material that can provide as the source of vapour phase composition has been provided Fig. 2, and these vapour phase compositions can be transferred inlet pipe 14 under controlled condition.Label 30 in Fig. 2 indicates a kind of volatility rare earth element, and it can be a vapour phase from solid-state distillation under the situation of aerobic.
For the vapor deposition method those skilled in the art, the red-tape operati process of lathe and blowtorch and the control process that delivers a vapor to the inside of pipe are all known, and therefore in this manual this are not further described.
When having deposited the quantity of desired quartz layer and doping quartz layer, composite structure is shunk to form solid plug 15 in pipe 14 inside.This in the art production process also is known, and, usually require to use blowtorch 18 and produce very high temperature repeatedly through so that comprise the structure of fibre core 10 and clad section 11 and 12 and shrink.
In the subordinate phase of making, illustrate that as Fig. 3 and 4 method by comprising flame hydrolysis is deposited on the radially outer clad section 13 of last preform on the plug 15.This is also referred to as outside chemical vapor deposition method or more generally is called OVD.
Be enough to be implemented in the settled layer in the whole viscosity agglomerating temperature by in suitable environment, composite structure being exposed to, sedimentary powdered granule or dust are solidified.This process is opposite with inner vapor deposition method, is to carry out sintering layer by layer in the process of deposition material by the MCVD method in inner gas deposition.Usually deposition extramural cladding 13 as shown in FIG. 3, adds selected doping agent to meet specific covering standard to form pure quartz layer in deposition process.
The two-phase method that can use manufacturing preform mentioned above is to form different index distribution in the fibre core of the core region of preform and the optical fiber that drawing thus from preform.A kind of such distribution of diacritic in theory dotted line region representation by (under the optical fiber situation as shown in Figure 5) among Fig. 1.As mentioned before, the gas deposition of control core structure 10 has relative high index n with formation
1 Central zone 26, have the refractive index n of being lower than
1But the specific refractory power (n that is higher than pure quartz
4) refractive index n
2 Outer region 27 and have the refractive index n lower than outer shroud specific refractory power
3Endocyclic area 28.Though the refractive index n of endocyclic area 28 is not shown in accompanying drawing 5
3The most preferably with the refractive index n of pure quartz
4Identical or be lower than the refractive index n of pure quartz
4
Fig. 6 to 10 has clearly illustrated the optic fibre characteristic of deriving in the different parameters of the optical fiber that expression draws from preform, described this preform in conjunction with Fig. 1 and Fig. 5.Yet term " ring (Ring) " is construed as the outer region 27 of core structure 10 as shown in Figure 1.
Claims (17)
1. a method of making preform can draw single mode optical fibre from this preform, and this method comprises the steps:
Use the quartz layer of inside deposition method at the inside of silica tube dopant deposition,
Before deposition of subsequent layers, solidify each adulterated quartz layer, so that the diffusion minimum of doping agent between layer,
The thermal contraction silica tube also makes sedimentary material form the solid plug,
By OVD coat in the outside of plug basic quartz material uniformly and
This covering plug is carried out the consolidation heating to finish the manufacturing of preform.
2. the method for manufacturing preform as claimed in claim 1, wherein, the inside at silica tube before the quartz layer of dopant deposition deposits quartz layer.
3. the method for manufacturing preform as claimed in claim 2, wherein, by inside deposition quartz layer and the adulterated quartz layer of modified chemical vapor deposition (MCVD) method at silica tube.
4. the method for manufacturing preform as claimed in claim 3, wherein, the control gas deposition is so that produced the viscosity sintering of deposited particles in each settled layer before each succeeding layer of deposition.
5. as the method for the described manufacturing preform of arbitrary claim in the claim 1 to 4, wherein, clad material is deposited on the outside of plug by outside gas deposition (OVD) method, and wherein sedimentary material solidifies in such a way, to implement the whole viscosity sintering of particulate in the deposition covering.
6. as the method for the described manufacturing preform of arbitrary claim in the claim 1 to 5, wherein, adulterated quartz layer is deposited on the inside of silica tube in such a way so that the area on-axis with at least three different refractivities is provided in the preform of being finished.
7. the method for manufacturing preform as claimed in claim 1 wherein, forms the solid plug to comprise the external region that a core region and forms the radially the inside part of preform covering.
8. the method for manufacturing preform as claimed in claim 7, wherein, quartz layer is deposited on the silica tube before the quartz of dopant deposition, and wherein the radially the inside part of preform covering is to form by the silica tube that shrinks with by the quartz layer that the inside deposition method is deposited on the inside of pipe.
9. the method for manufacturing preform as claimed in claim 7, wherein, quartz layer and adulterated quartz layer are deposited on the inside of silica tube in such a way, so that plug is to form in the core region that includes following three area on-axis:
A) has relative high index n
1The central zone,
B) has lower refractive index n
2Outer shroud and
C) have the refractive index n lower than outer shroud specific refractory power
3Interior ring.
10. the method for manufacturing preform as claimed in claim 9 wherein, adds doping agent in such a way in deposition material, so that formation has refractive index n
3Interior ring, and refractive index n
3Also lower than unadulterated quartzy specific refractory power.
11. method as claim 9 or the described manufacturing preform of claim 10, wherein, implement the quartzy gas deposition that mixes in such a way, so that reach the fractionated specific refractory power at least one zone in the outer shroud of core region, interior ring and central zone.
12. as the method for the manufacturing preform described in arbitrary claim in front, wherein, the vapour phase that forms undoped quartzy steam by oxidation in torch flame becomes the outside of the core rod of assigning to, and controls this blowtorch so that it moves around on the whole length of plug substantially.
13. the method for manufacturing preform as claimed in claim 1, wherein, adulterated quartz contains the doping agent that is selected from germanium, boron, lead and the fluorine.
14. the method for claim 1, wherein adulterated quartz contains rare earth doped dose.
15. the method for manufacturing preform as claimed in claim 14, wherein, doping agent comprises erbium and/or ytterbium.
16. according to a kind of preform of making in the method described in aforesaid arbitrary claim.
17. from a kind of optical fiber that the preform described in the claim 16, draws.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00106544 CN1287103A (en) | 2000-03-07 | 2000-03-07 | Prcess for producing precast blank |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00106544 CN1287103A (en) | 2000-03-07 | 2000-03-07 | Prcess for producing precast blank |
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| Publication Number | Publication Date |
|---|---|
| CN1287103A true CN1287103A (en) | 2001-03-14 |
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|---|---|---|---|
| CN 00106544 Pending CN1287103A (en) | 2000-03-07 | 2000-03-07 | Prcess for producing precast blank |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109642983A (en) * | 2016-08-30 | 2019-04-16 | 株式会社藤仓 | Optical fiber |
| CN114455828A (en) * | 2022-02-18 | 2022-05-10 | 锐光信通科技有限公司 | Method for manufacturing boron-doped stress rod |
-
2000
- 2000-03-07 CN CN 00106544 patent/CN1287103A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109642983A (en) * | 2016-08-30 | 2019-04-16 | 株式会社藤仓 | Optical fiber |
| US10670812B2 (en) | 2016-08-30 | 2020-06-02 | Fujikura Ltd. | Optical fiber |
| CN109642983B (en) * | 2016-08-30 | 2020-09-25 | 株式会社藤仓 | Optical fiber |
| CN114455828A (en) * | 2022-02-18 | 2022-05-10 | 锐光信通科技有限公司 | Method for manufacturing boron-doped stress rod |
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