CN1017613B - Prefabricated glass blank for producing optical fibre - Google Patents
Prefabricated glass blank for producing optical fibreInfo
- Publication number
- CN1017613B CN1017613B CN 85101685 CN85101685A CN1017613B CN 1017613 B CN1017613 B CN 1017613B CN 85101685 CN85101685 CN 85101685 CN 85101685 A CN85101685 A CN 85101685A CN 1017613 B CN1017613 B CN 1017613B
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- precast billet
- geo
- sintering
- glass
- settling
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Abstract
The present invention relates to a method for producing preformed glass blanks, which comprises: quartz glass granules are generated by hydrolyzing glass material in oxyhydrogen flames; the solid or hollow cylindrical deposited preformed blanks can be produced by depositing the quartz glass granules on seed pieces, wherein at least part of the preformed blanks contain GeO2; the deposited preformed blanks are conveyed into atmosphere containing inert gas for heating and sintering, wherein the conveying speed is not less than three millimeters per minute, and at least the temperature of part of the atmosphere is not lower than 1600 DEG C. The preformed blanks produced by using the method can be drawn into optical fibers with ingredients distributed uniformly in the vertical direction and low attenuation of light transmission.
Description
The production method of glass preform during the relevant optical fiber of the present invention is made.In more detail, the method for the relevant production glass preform of the present invention is to be suitable for making vertically evenly forming and the optical fiber very little to optical transmission attenuation.
The mass production method that is suitable for making fibre-optic glass preform comprises vapour phase axial deposition technique (hereinafter being " VAD " method) and surperficial vapour deposition process (hereinafter being " OVPD ").These sedimentations are included in that the flame hydrolysis frit generates pure quartz (SiO in a kind of oxyhydrogen flame
2) the little material of glass or contain a kind of additive such as GeO
2The doping quartz, its mean particle size is 0.1 micron.Glass granules is deposited on the seed spare, produces a kind of porous dust deposit precast billet (Soot preform), at high temperature sintering dust deposit precast billet just can obtain transparent glass preform.According to the VAD method, glass granules is deposited on the rotation seed spare parallel with seed spare turning axle, can produce solid cylindrical deposition precast billet (referring to U.S. Pat patent4,135,901) continuously.According to the OVPD method, the glass micron is deposited on the rotation seed rod of being done by aluminum oxide or silica glass, its direction and excellent turning axle direction meet at right angles, and produce the multiwalled glass granules (referring to U.S. Pat patent3,711,262; 3,737,292 and 3,737,293).The porous dust deposit precast billet of producing is placed under the atmosphere of a kind of inert gas such as helium, thereby make the transparent glass preform that obtains of deposition precast billet with heat and sintering.In general, to deposit doping such as GeO in the precast billet to porous for the specific refractory power of regulating the deposition precast billet
2Yet because additive is that heat is volatile, so at high temperature will in precast billet, evaporate.In addition, because additive is wanted partly or all volatilizations in sintering process, be out of the question so in producing deposition precast billet process, regulate specific refractory power.
This to prevent temperature that the volatilization of additive, someone advise the heating deposition precast billet higher at least 200 ℃ than making it and become the minimum temperature when transparent, but can not surpass 1600 ℃ (referring to Japanese patent laid-open publication gazette 3981/1983).
Yet, some shortcoming of the method that Japanese patent laid-open publication gazette is revealed, it is very poor that the glass preform that adopts this method to produce is made its light transitivity of optical fiber, and the decay of transmitting as light increases a lot, and this is owing to produce the lower cause of temperature of glass preform.For example, as content (weight) 25%GeO
2SiO
2The deposition precast billet of glass granules is when 1350 ℃ of following sintering, and the minimum sintering temperature that this temperature produces the transparent glass precast billet is high 75 ℃, has produced a kind of transparent glass precast billet.When wavelength is 0.85 micron, decay to 10-20 decibel/km (dB/Km) by the optical fiber of this glass preform manufacturing, it is the highest theoretical value of 3 decibels/km that this numerical value is far longer than its value.Find that the reason that this optical delivery decay increases is Ge
2+Existence, it makes glass preform produce textural defect.
In addition, when above-mentioned optical fiber temperature remained on 200 ℃, the hydrogen that exists in the fiber from the covering material of fiber and/or from air, was diffused in the textural defect and Ge
2The space dot matrix, reaction generates GeOH.React as follows:
This has just caused the increase of residual hydroxyl quantity.Well-known hydrogen is easy to infiltrate in the glass material.
Because there is a peak at the wavelength place that is absorbed near 1.39 microns of residual hydroxyl, it will influence the light transmission of used 1.30 microns wavestrips in communication and increase the absorption of 1.30 micron wave lengths.The acceptance value that increases at this wavestrip optical transmission attenuation is 1.0 a decibels/km or littler.As time goes on decay improves 0.2 decibel/km and just is called and has bigger adverse affects on the communication system.
Optical fiber has Ge
2+The textural defect that still exists and cause not only makes fibre-optic light transmission degenerate, but also has improved the amount of the hydroxyl that can influence optical fiber life-time service reliability.In addition, being desirable to provide very much a method can produce glass preform and not have Ge to be applicable to make
2+The optical fiber of adverse affects.
The purpose of this invention is to provide one is to reduce because of Ge than routine production
2+The glass preform production method of the textural defect that causes.
Another object of the present invention provides a kind of method of producing glass preform, the optical fiber that draws by this precast billet its forms even on vertically and optical transmission attenuation low.
Therefore, the invention provides a method of producing glass preform flame hydrolysis frit and generate the silica glass particulate in oxyhydrogen flame.Glass granules is deposited on the seed spare and has produced a kind of solid or hollow cylindrical deposition precast billet, and this base has at least some to contain GeO
2The heating of glass preform and sintering are by in the atmosphere that is placed on rare gas element such as helium, and temperature at least partly keeps being not less than 1600 ℃, and the speed of sending into is not less than 3 millimeters/minute.
Have at least part deposition precast billet to contain GeO
2, and this GeO
2Amount will help and produce refractive index gradient in the precast billet.
Fig. 1 is ultraviolet (UV) spectrum of four kinds of glass in the table 1;
Fig. 2 is expression GeO
2The curve of volatile quantity and temperature mutual relationship;
Fig. 3 is used for the stove of embodiment sintered deposit precast billet with graphic extension;
Fig. 4 explanation is in glass preform outward appearance of producing by example 1 and sintering temperature and deposit the mutual relationship that precast billet is sent into speed.
The GeO that adds2Amount and because Ge2Produce the relation of fault of construction amount.
Join GeO in the quartz glass in order to seek2Amount and by Ge2Cause the relation between the fault of construction amount, produced four kinds with the VAD method and contained various GeO2The SiO of amount2-GeO
2The deposition prefabricated blank.
The deposition prefabricated blank heats in pure helium-atmosphere, is raised to 1500 ℃ (No. 1 to No. 4) with 3.3 ℃/minute programming rates from 800 ℃. GeO in the glass preform2Concentration and refringence (△ n) list in table 1, and the ultraviolet spectra of 4 kinds of glass is shown in Fig. 1.
As shown in Figure 1, GeO2Content is more high, 2450 dusts (
) absorb under the wavelength more many. Owing in pure quartz, do not have this absorption, so can say just because of GeO2Existence, the absorption in ultraviolet range is caused by fault of construction. Corresponding to the absorption of wavelength 2450 dusts, absorb take wavelength as 0.45 and 0.63 micron appearance, its impact namely owing to appearance hangover in 0.80-1.60 micron wave length scope, thereby has increased absorption. Much less, reduce that the absorption of used optical fiber in this scope is very important in the communication.
GeO
2Heat volatilization
Adopt the VAD method to produce a kind of SiO
2-GeO
2(SiO
2To GeO
2Weight ratio=90: 10) particulate glass deposition precast billet and heating 3 hours in 1200 ℃ of pure helium-atmospheres, precast billet directly upwards shrinks 30% at it, and heating back glass component is the SiO of (weight) 94%
2, (weight) 6% GeO
2The variation of this component is because GeO
2It is caused to volatilize, and its volatilization can be undertaken by following reaction formula:
(g) means gaseous state herein.Known GeO distils when being not less than 800 ℃.
Press above-mentioned reaction formula II to GeO
2The research of heat volatilization and temperature mutual relationship has disclosed at GeO
2Between the evaporation rate (W weight %/minute) of deposition precast billet and absolute temperature T ° K is to exist a kind of relation, and this mutual relationship can be expressed with following equation as shown in Figure 2:
W＝2.9×exp（-Ea/RT） （Ⅲ）
R is 1.987 card/degree mole (cal/degmole) .Ea=12.0 kcal/mol (kcal/mole) (referring to 8th Conferencl of Optical Communication(CANNES) in the formula, C-15,629-632(1982)).
Understand GeO according to the equation formula III
2Hot evaporation rate relevant with temperature and when temperature raises evaporation rate also increase.
Have found that (the glass component is SiO by weight as above-mentioned same deposition precast billet
2Be 90%, GeO
2Be 10%) under 1700 ℃ of pure helium-atmospheres, heat, precast billet just was transformed into transparent glass preform in 5 minutes, and the glass preform that obtains contains the GeO of 9.5% weight
2This result means GeO
2Basically do not have volatilization, as if inconsistent with top equation.Yet this phenomenon can be done description below:
Although GeO
2Evaporation rate is very low in the time of 1200 ℃, and the deposition precast billet is still slowly shunk, and after 3 hours, diametrically high energy shrinks 30%, and glass particle can have sizable specific surface (gram per centimeter
3).In addition, GeO
2Also volatilize from particle surface.Therefore, GeO
2(VGeO) volatile quantity and sintering temperature, the product of specific surface (S) and sintering time (t) is directly proportional, and is expressed as follows:
V
GeOαS×t×exp（-Ea/RT） （Ⅳ）
Ea is the same with R with the explanation of front in the formula.According to this relation, be appreciated that and promptly use equation (III), the evaporation rate of expression is very little, but as long as the specific surface of precast billet is big, GeO
2Volatile quantity still increase with the heating of deposition precast billet.
On the contrary, heating when at 1700 ℃, although the 3-4 when evaporation rate is 1200 ℃ is doubly, the deposition precast billet can very fast contraction, and GeO
2The volatilization time shortened to less than 5 minutes, when this time is 1200 ℃ 1/36 of systolic time.Like this, volatile quantity only is 1/10(3-4 * 1/36) about.This just means by suppressing GeO effectively in the temperature sintered deposit precast billet the energy fast contraction
2Volatilization.
Because GeO
2With the textural defect that sintering temperature produces, utilize the VAD method to produce and contain weight 75%SiO
2With weight 25%GeO
2Two kinds the deposition precast billet, and in pure helium atmosphere 1375 ℃ or 1650 ℃ of following sintering, to obtain two kinds of transparent glass preforms.The UV spectrum of glass preform shows that sintering has more defects than sintering under comparatively high temps at a lower temperature.By absorbing the ratio estimation, the former agglomerating defective is higher 10 times than latter's agglomerating defective at wavelength 2450 dust places.
This just means the generation and the GeO of textural defect
2Volatilization substantial connection is arranged.This phenomenon can be done description below:
GeO according to reaction formula II, generation is retained in the glass preform Ge in that blank
2+Content will increase, and its reason is, because GeO molecular ratio oxygen molecule is huge, causes the diffusion ratio oxygen molecule difficulty of GeO molecule, and it is bigger than oxygen molecule that concentration also can become, and this has just suppressed reaction (I) Ge
2+[(GeO) → Ge
4+(GeO
2)] backward reaction.
Therefore, be understood that, suppress GeO
2Volatilization, this for reducing because Ge
2+The defective that causes is very important.
According to above basic discussion, be understood that sintering condition, particularly sintering temperature and its hysteresis phenomenon have play a part important in the low blank of production defective.
According to the present invention, sintering temperature is preferably 1600 ℃-2000 ℃, is being higher than under 1600 ℃ the temperature, shrinks because of the deposition precast billet, has suppressed GeO
2Volatilization, transparent thereby blank becomes.Be higher than under 2000 ℃ the temperature, transparent glass can be expanded slightly, makes random that its diameter becomes.
Preferably with the 3-20 millimeter/minute speed will deposit precast billet and send in the sintering atmosphere.When transfer rate greater than 20 millimeters/timesharing, bubble is easily stayed in the blank, the blank centre is difficult for being heated, thereby causes can staying translucent body in the centre.This is because micro-bubble is caused.Simultaneously, when being drawn into optical fiber, produce bubble by glass blank.
GeO in the silica glass
2Content is preferably (weight) 15-80%.According to the present invention, before sintering, the deposition precast billet can be placed according to ordinary method that to contain chlorine compound (be Cl
2, SOSl
2, COCl
2, CCl
4Deng) inert gas atmosphere in dewater.
Here utilize following example further to explain the present invention.
In example, adopt stove heating and sintered deposit precast billet shown in Figure 3.Number in the figure 1,2,3,4,5,6 and 7 is represented deposition precast billet, support stick, muffle tube, well heater, body of heater, gas inlet and outlet respectively.
Example 1(1)-(17)
Produce 17 with the VAD method and contain (weight) 75%SiO
2(weight) 25%GeO
2The quartz glass deposition precast billet, (millimeter/minute) sent into each deposition precast billet in the stove that keeps preset temperature at a predetermined velocity, temperature is higher than 1000 ℃ in the stove, thermograde is 45 ℃/centimetre, it is transparent that precast billet is burnt till.Furnace atmosphere is pure helium.
Fig. 4 has shown the glass preform outward appearance of being produced, the relation between sintering temperature and the deposition precast billet transfer rate.Among Fig. 4, two circles " ◎ ", triangle " △ " and cross " * " are represented " transparent fully ", " almost transparent " and " translucent " respectively.Putting into practice (a) and dotted line (b) represents to produce the lower bound of complete transparent glass precast billet respectively and produces the almost sinking of transparent glass precast billet.Position A, B, C represent to produce transparent fully respectively, the scope of almost transparent and translucent glass precast billet.
From these results as can be seen, when when sending into greater than 3 millimeters/minute speed, the temperature of sintered deposit precast billet preferably is not less than 1610 ℃.When sending into less than 2 millimeters/minute speed, sintering temperature must be not less than 1580 ℃, otherwise can produce translucent precast billet.
The optical fiber that is drawn by complete transparent glass precast billet contains a little bubble, and when being drawn by the translucent glass precast billet, contains numerous air-bubble.
Sending into, and the glass preform that produces, be that 0.85 micron optical transmission attenuation is 3-4 decibel/km with this optical fiber that draws, wavelength greater than 3 millimeters/minute speed.Sending into greater than 2 millimeters/minute speed, the glass preform that is produced, the optical fiber of La Zhiing decays to 10-20 decibel/km with identical wavelength light transmission thus.
Example 2
In the mode identical, but send into 15 millimeters/minute speed in the stove of 1750 ℃ of temperature with example 1, used identical deposition precast billet in sintering and the example 1, the glass preform that obtains contains numerous air-bubble in the centre.
Example 3
In the mode identical with example 2, but send into this deposition precast billet of sintering in the stove with 5 millimeters/minute speed, obtain not having bubble transparent glass preform fully, with the optical fiber of this glass preform drawing, with 0.85 micron wavelength, optical transmission attenuation is not more than 3 decibels/km.
Example 4
Contain (weight) 15%GeO with the mode sintering identical with example 1
2The quartz glass deposition precast billet, to send into, under greater than 1600 ℃, obtain fully transparent glass preform greater than 3 millimeters/minute speed, with the optical fiber of this precast billet drawing, with 0.85 micron wavelength, optical transmission attenuation is 2.3-2.8 decibel/km.
Example 5
In the mode identical with example 4, but the speed of sending into is 1 millimeter/minute, sintered deposit precast billet in 1500 ℃ stove, and to obtain glass preform, with the optical fiber of this production, with 0.85 micron wavelength, optical transmission attenuation is 4-5 decibel/km.This means that it is because Ge that light transmits weak about 2 decibels
2+Absorb institute extremely.
Example 6
Before the sintering, will deposit precast billet and place 1100 ℃ of helium-atmospheres that contain (volume) 5% chlorine to dewater, then,, produce identical glass preform and optical fiber with the mode sintering identical with example 4.Remaining hydroxyl is less than 0.1ppm.
Example 7
With 3 millimeters/minute speed carry with example 1 in used identical deposition precast billet be sintering in 1600 ℃ of stoves of 20 ℃/centimetre or 65 ℃/centimetre to thermograde, obtain transparent glass preform fully, with the optical fiber of this drawing, with 0.85 micron wavelength, not because of Ge
2+Absorb and the decay of increase light transmission.
This result means, carries with speed greater than 3 millimeters/minute, and be 20-65 ℃/centimetre the 1600 ℃ of following sintered deposit precast billet that are higher than in thermograde, the glass preform of generation is without any bubble.Simultaneously because Ge
2+The photoabsorption that causes can reduce.
Example 8
In the mode identical with example 7, the deposition precast billet that sintering OVPD method is produced, its result is identical with example 7.
Taken passages above each routine result in the table 2.
Table 1
Number number glass component △ n(%) GeO
2(weight %)
1 SiO
2- -
2 SiO
2-GeO
20.5 8.5
3 SiO
2-GeO
21.0 17
4 SiO
2-GeO
21.6 27
Claims (7)
1, a kind of method of producing glass preform, this method is included in the oxyhydrogen flame carries out flame hydrolysis with a kind of frit, to form the silica glass fine particle; Described glass fine particle is deposited on the seed spare, forms the settling precast billet of a kind of solid cylinder or open circles tubular, the part of this precast billet contains GeO at least
2Send into this settling precast billet in the inert gas atmosphere and make its at least a portion keep at least 1600 ℃, heat and sintering, it is characterized in that the speed that this settling precast billet is sent in the described atmosphere is at least 3 mm/min, and the contained GeO of at least a portion of described precast billet
2Amount is at least 15% (weight).
2, according to the process of claim 1 wherein that described sintering temperature is 1600-2000 ℃.
3, according to the process of claim 1 wherein that described transfer rate is the 3-20 mm/min.
4, according to the process of claim 1 wherein described GeO
2Content be (weight) 15-80%.
5, according to the process of claim 1 wherein that described rare gas element is a helium.
6,, further be included in the step of dewatering before the settling precast billet sintering according to the method for claim 1.
7, according to the method for claim 6, the dehydration of wherein said settling precast billet is to carry out in the atmosphere that contains a kind of rare gas element and a kind of chlorine-containing compound.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85101685 CN1017613B (en) | 1985-04-01 | 1985-04-01 | Prefabricated glass blank for producing optical fibre |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85101685 CN1017613B (en) | 1985-04-01 | 1985-04-01 | Prefabricated glass blank for producing optical fibre |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN85101685A CN85101685A (en) | 1987-01-24 |
| CN1017613B true CN1017613B (en) | 1992-07-29 |
Family
ID=4791999
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 85101685 Expired CN1017613B (en) | 1985-04-01 | 1985-04-01 | Prefabricated glass blank for producing optical fibre |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1017613B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1052464C (en) * | 1995-11-03 | 2000-05-17 | 康宁股份有限公司 | Optical fiber resistant to hydrogen-induced attenuation |
-
1985
- 1985-04-01 CN CN 85101685 patent/CN1017613B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN85101685A (en) | 1987-01-24 |
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