CN88100850A - The manufacture method of high bandwidth multimode graded-index optical fiber - Google Patents

The manufacture method of high bandwidth multimode graded-index optical fiber Download PDF

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CN88100850A
CN88100850A CN88100850.8A CN88100850A CN88100850A CN 88100850 A CN88100850 A CN 88100850A CN 88100850 A CN88100850 A CN 88100850A CN 88100850 A CN88100850 A CN 88100850A
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optical fiber
high bandwidth
gecl
carrier gas
manufacture method
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CN1012363B (en
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梁建明
王旭华
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HANGZHOU RADIO MATERIALS FACTORY
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HANGZHOU RADIO MATERIALS FACTORY
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Abstract

The present invention is a kind of method of making the high bandwidth multimode graded-index optical fiber with MCVD technology.Adopt the first-order approximation method to realize the accurate control of optical fiber precast rod refractivity, the benefit core combines with corrosion and has obtained extremely narrow refractive index of the centre depression during burning shrinkage.The dispersiveness of profile exponent α in conventional 0 trial and error method and the experience correction method and the problem of poor repeatability have been solved.The multimode optical fibers specific refractory power control accuracy of manufacturing reaches 5 * 10 -5, the 1.3 μ m average bandwidth＞1700MHzkm of place are up to 5GHzkm, and transmission loss 0.5～1.0dB/km can be used for three, the fourth order group fiber optic communication field.

Description

The invention belongs to the fibreoptics field.
The theoretical formula that the multimode graded-index optical fiber fiber core refractive index distributes is:
n r＝n 1〔1-2△（ (r)/(a) ） α〕 1/2（O≤r≤a） （1）
In order to make the optical fiber of the profile exponent α that has formula shown in (1), conventional way is to adopt O trial and error method to control main doping agent G eCl 4Carrier gas flux F iMove number of times i with respect to blowtorch and change (Review of the Electrical Communication Laboratories 1980 by formula (2).Vol 29，NO2，233-246）。
F i＝F o〔1-（1- (i)/(N) ） α/2〕 （2）
F in the formula oG during for i=N eCl 4Carrier gas flux,
N is the total frequency of depositing of sandwich layer,
α is a profile exponent.
Two basic assumption conditions are depended in the establishment of formula (2):
1. each settled layer volume equates.
2. each settled layer refractive index contrast and main doping agent G eCl 4Carrier gas flux be directly proportional.
This article admits that this O trial and error method easily produces dual α, and aspect the bandwidth repeatability problem is being arranged also.Its bandwidth of the optical fiber that makes in this way is at the 1.06 average out to 560MH of μ m place
Figure 88100850_IMG1
Km, the dispersion value of average alpha are 0.11.
In order to improve the transmission bandwidth of optical fiber, people have studied the method that accurately reaches basic assumption condition 1.The method that has proposed to increase argon gas as mentioned in carrier gas and successively reduced argon flow amount, prepared 10 optical fiber average bandwidths reach 900MH at 1.06 μ m places ZKm.The method of the change blowtorch speed that proposes in and for example (openly speciallyying permit the clear 58-64236 of communique), but its technology controlling and process is very complicated.
The somebody adopts experience correction method, and promptly by a large amount of tests, statistics draws by the experience factor of the various external factor decision result to O trial and error method and revises.As Shanghai transmission line institute (1.3 μ m long wavelength graded index multimode optical fiber precast rod research reports.1983。) correction formula that obtains is:
F i＝F o〔1-（1- (i)/(N) ） α/2〕+A（1- (i)/(N) ） （3）
A is a correction factor in the formula (3), and this coefficient is determined by factors such as depositing temperature, silica tube shrinkage and dopings.The optical fiber average bandwidth that makes in this way is 679MH ZKm.
And for example the segmentation correction formula of (CN85 1 02771A 1986.7.) proposition is:
Figure 88100850_IMG2
F in the formula oBe G eCl 4The initial set(ting)value of carrier gas flux,
A, B are given G eCl 4The carrier gas flux increment,
N is the positive integer between the O～(N)/10,
F nG during for i=n eCl 4Carrier gas flux
The correction factor and the set(ting)value that need test to determine in the formula (4) reach 4.Yan Zhi optical fiber is at the 1.3 μ m average bandwidth 〉=800MH of place in this way ZThe 53.8%(MCVD legal system that only accounts for of Km is equipped with optical fiber preform research report.Tianjin the 46 institute of the ministry of electronics industry, 1985).
Above-mentioned two kinds of revised laws have all been obtained certain effect under their condition separately, but because the test work amount is big, the influence that the many external conditionss of correction factor audient change is very complicated to be difficult to determine that specific refractory power control accuracy and repeatability are still relatively poor.Although some high bandwidth optic fibres are also arranged, ratio is not high.All only get in their method in addition the trace the P doping content (0～0.4mol%), its sedimentation rate lower (≤0.1 Grams Per Minute).
Improving the refractive index of the centre depression in the MCVD method is important measures that guarantee transmission bandwidth.Usually when burning shrinkage, adopt G eCl 4Mend the core method.G eCl 4Carrier gas flux is respectively 10ml/min and 8-20ml/min in above-mentioned two kinds of revised laws.This benefit core method exists mends the not enough or excessive danger of core.Someone adopts CCl in the PCVD method 2F 2Etch replaces G eCl 4Mend the core method and (mix the research of fluorine multimode optical fibers with the PCVD prepared.Wuhan Institute of Post and Telecommunication, 1985.).In the MCVD method,, adopt etch to exist the problem that etching extent is difficult for grasping even enlarging depression merely because the deposition number of plies is few, and each settled layer is thicker.
The objective of the invention is to fundamentally find a kind of optical fibre refractivity simple, feasible, the energy widespread usage accurately to control method, improve the bandwidth level of MCVD manufactured multimode optical fibers significantly.
The 1st the basic assumption condition that it is considered herein that conventional 0 approximate French (2) is to obtain easily better satisfying, and key is refringence and G in the primary condition 2 eCl 4The hypothesis that carrier gas flux is directly proportional is actually invalid, thereby the fiber core refractive index of obtained optical fiber exists the inherent deviation.And various revised laws are because the variation of external conditions and value is calculated when revising error can not be carried out accurately this deviation revises.Make profile exponent α depart from optimum value ± 0.06 as long as result of theoretic analysis shows, just can make order of magnitude of fiber bandwidth decline.In order to obtain＞1GH ZThe multimode optical fibers of Km, index distribution to the deviation of optimum value necessary＜1 * 10 -4
In order to eliminate this inherent variability that exists in O trial and error method, the present invention is to find out each settled layer refractive index contrast and G eCl 4Funtcional relationship correct between the carrier gas flux is a target, derives main doping agent G eCl 4Carrier gas flux F iMove the relation of number of times i with respect to blowtorch.
The present invention is a kind of manufacture method of high bandwidth multimode graded-index optical fiber, and (deposition component is F-P in quartzy armor hose to adopt MCVD prepared optical fiber precast rod 2O 5-S iO 2The covering of three component system, deposition component are G eO 2-P 2O 5-S iO 2Only change main doping agent G during the sandwich layer of three component system eCl 4Flow, the silica tube burning shrinkage that deposition is good becomes solid bar), then with gained precast rod drawing optic fibre, when the preparation preform, adopt first-order approximation method control G eCl 4The carrier gas flux variation of moving number of times with respect to blowtorch, the calculation formula of first-order approximation is as follows:
F i＝F o〔1-（1- (i)/(N) ） α/2〕·｛1+β〔1-（1- (i)/(N) ） α/2〕｝（5）
In the formula: the number of times that blowtorch moved when i was the deposition sandwich layer,
F iBe i layer G eCl 4Carrier gas flux (ml/min),
N is the total frequency of depositing of sandwich layer,
F oG during for i=N eCl 4Carrier gas flux (ml/min),
α is a profile exponent,
β is the G of feed composition decision eCl 4Content.
Second β (1-(1-(i)/(N)) in the formula (5) in the braces α/2) be the nonlinear factor that the basic assumption condition 2 of O trial and error method is lost, so the present invention abbreviates the first-order approximation method as.
It is that each settled layer volume equates that the establishment of formula (5) only needs a basic assumption condition.
Obviously in the funtcional relationship of formula (5), main doping agent G eCl 4The calculating of flow only relates to the influence of feed composition, without any the correction factor relevant with ambient conditions.Therefore a GPRS conventional MCVD technology, just can directly use the multimode graded-index optical fiber of first-order approximation manufactured high bandwidth of the present invention.
The present invention adopts MCVD prepared optical fiber precast rod.Refractive Index Profile o is the core pack arrangement that ditch is arranged, △ +=1.0% △ -=0.14%.Select the quartzy armor hose of Heralux φ 20 * φ 16 * 1000mm for use, a termination skirt cleans with diluted hydrofluoric acid, and high purity water washes down, and dock with φ 40mm tail pipe on the gas deposition glass work lathe dry back, with moisture content and the surperficial microdefect in the high temperature removing silica tube.Depositing the 5-7 layer component then is F-P 2O 5-SiO 2The covering of three component system, deposition 40～45 layer components are G eO 2-P 2O 5-SiO 2Only change main doping agent G during the sandwich layer of three component system eCl 4Flow.Each layer G eCl 4Carrier gas flux is by formula (5) control, and depositing temperature is 1800 °～1850 ℃, 20 °～30 ℃ of material temperatures, and deposition finishes and improves the blowtorch temperature, reduction blowtorch translational speed becomes solid bar with the silica tube burning shrinkage.Adopt during burning shrinkage and mend the extremely narrow refractive index of the centre depression of method acquisition that core combines with corrosion, its normalization method width≤0.04.Mend the G of core eCl 4Carrier gas flux is 6～8ml/min, etching reagent CCl 2F 2Flow is 5～8moi%.
The a collection of multimode graded-index optical fiber 1.3 μ m average bandwidth＞1700MH of place that adopt the present invention to make ZKm, wherein＞1000MH ZKm accounts for 76.4%,＞2000MH ZKm accounts for 41.4%, is up to 5000MH ZKm.1.3 μ m place's loss is 0.5～1.0dB/Km.The sedimentation rate of not using helium is 0.21～0.23 Grams Per Minute.The dispersion value of average alpha＜0.08.The optical fibre refractivity control accuracy of this method manufacturing reaches 5 * 10 -5, improved one more than the order of magnitude than 0 trial and error method.
Provide the example of two optical fiber:
According to the structure and the design of components of optical fiber, by conventional MCVD prepared optical fiber precast rod.Get α=1.88, N=40, material flow sees Table 1.
Table 1 (ml/min)
SiCl 4G eCl 4CCl 2F 2POCl 3O 2
Covering 200 10 60 1000
Sandwich layer 200 0～300 60 1000
Each layer of sandwich layer G by formula of the present invention (5) calculating eCl 4Carrier gas flux sees Table 2:
Table 2 (ml/min)
1 5.5 11 62.5 21 129.0 31 208.5
2 10.5 12 68.5 22 136.0 32 217.5
3 16.0 13 75.0 23 143.5 33 226.5
4 21.5 14 81.0 24 151.0 34 236.0
5 27.0 15 87.5 25 159.0 35 245.5
6 33.0 16 94.5 26 167.0 36 255.5
7 38.5 17 101.0 27 175.0 37 265.5
8 44.5 18 108.0 28 183.0 38 276.5
9 50.5 19 114.5 29 191.5 39 287.5
10 56.5 20 122.0 30 200.0 40 300.0
Each layer G eCl 4The normalizing rate of carrier gas flux is seen Fig. 1.
See Fig. 2 by the refractive index distribution curve that YOrk-PlOl precast rod analyser provides, the upper left corner is the pulse strenching curve of optical fiber that this rod draws among the figure.
See Fig. 3 by fiber bandwidth and response curve that YOrk-FCM1000 optical fiber full performance test instrument provides.
See Fig. 4 by the optical fiber mode delay inequality that the HP8410 microwave network analyzer provides, maximum delay difference τ Max=200PS/Km, bandwidth B m=5GH ZKm.The deviation of optical fibre refractivity and best index distribution is seen Fig. 5, and its control accuracy reaches 5 * 10 -5
The gained optical fiber property sees Table 3.
Table 3
Optical fiber numbering: HZ87-4-12 HZ87-4-14
Core diameter size: (μ m) 50/,125 50/125
Numerical aperture: 0.20 0.19
1.3 μ m loss (dB/Km) 0.79 0.81
1.3 μ m bandwidth (MH ZKm) 5,000 3400

Claims (3)

1, a kind of manufacture method of high bandwidth multimode graded-index optical fiber, (it is F-P that this technology is included in the interior deposition component of quartzy armor hose to adopt MCVD prepared optical fiber precast rod 2O 3-SiO 2The covering of three component system, deposition component are GeO 2-P 2O 5-SiO 2Only change main doping agent GeCl during the sandwich layer of three component system 4Flow, the silica tube burning shrinkage that deposition is good becomes real plug), then with gained precast rod drawing optic fibre, it is characterized in that adopting first-order approximation method control GeCl 4Carrier gas flux F iWith respect to the variation that blowtorch moves number of times i, the calculation formula of first-order approximation is as follows:
F i=Fo[1-(1- (i)/(N) ) a/2]·{1+β[1-(1- (i)/(N) ) a/2]}
F in the formula iBe the GeCl of i layer 4Carrier gas flux (ml/min),
The number of times that blowtorch moved when i was the deposition sandwich layer,
N is the total frequency of depositing of sandwich layer,
F oGeCl during for i=N 4Carrier gas flux (ml/min),
α is a profile exponent,
β is the GeCl of feed composition decision 4Content.
2, the manufacture method of high bandwidth multimode graded-index optical fiber according to claim 1 is characterized in that POCl 3Doping is 3-3.5mol%.
3, the manufacture method of high bandwidth multimode graded-index optical fiber according to claim 1 adopts G when it is characterized in that burning shrinkage eCl 4Mend core and CCl 2F 2The method that corrosion combines obtains extremely narrow refractive index of the centre depression.
CN 88100850 1988-02-10 1988-02-10 Process for high bandwidth gradually changing model multimould optical fibre Expired CN1012363B (en)

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CN1012363B CN1012363B (en) 1991-04-17

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7043126B2 (en) 2003-07-18 2006-05-09 Fujikura Ltd. Graded-index multimode fiber and manufacturing method therefor
CN102736169B (en) * 2011-03-29 2016-03-16 德拉克通信科技公司 Multimode optical fiber and optical system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7043126B2 (en) 2003-07-18 2006-05-09 Fujikura Ltd. Graded-index multimode fiber and manufacturing method therefor
CN102736169B (en) * 2011-03-29 2016-03-16 德拉克通信科技公司 Multimode optical fiber and optical system

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