CN103663958A - Method for preparing low water peak optical fiber preform - Google Patents
Method for preparing low water peak optical fiber preform Download PDFInfo
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- CN103663958A CN103663958A CN201310437888.0A CN201310437888A CN103663958A CN 103663958 A CN103663958 A CN 103663958A CN 201310437888 A CN201310437888 A CN 201310437888A CN 103663958 A CN103663958 A CN 103663958A
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Abstract
The invention relates to a method for preparing a low water peak optical fiber preform, which comprises the following steps: (a) depositing powder containing SiO2, GeO2 and the like on a target bar through vapor axial deposition (VAD); (b) after the powder body is deposited on the target bar, withdrawing the target bar from the powder body; (c) mounting a holding mechanism at one end of the tubular powder body and a plug at the other end, feeding the powder body into a heating furnace filled with dewatering gas and heat-conducting gas by means of the holding mechanism, and dewatering and sintering the tubular powder body to obtain a tubular glass body; (d) welding extension tubes at both ends of the sintered tubular glass body, eroding in a liquid containing hydrofluoric acid, cleaning the central hole region and the external surface, and drying in a clean; (e) transferring the dried tubular glass body into an electrothermal furnace containing oxygen gas and fluorine-containing gas, and performing melting shrinkage; and (f) cladding the stretched glass bar in optical fibers or directly performing wire drawing to form optical fibers.
Description
Technical field
The invention belongs to fiber optic communication field, relate to a kind of manufacture method of preform, specifically a kind of vapour phase axial deposition technique (VAD) is prepared the manufacture method of preformod of optical fiber with low water peak in large size.
Background technology
Preform manufacture generally adopts two-step process, first manufactures plug, then at mandrel outer, adopts different technology to manufacture surrounding layer.Typical plug manufacture method has following four kinds: modified chemical vapor deposition method (MCVD), plasma-enhanced chemical vapor deposition method (PCVD), pipe outside vapor deposition (OVD) and axial vapor deposition method (VAD).Surrounding layer manufacturing technology has tiretube process and Direct precipitation outsourcing according to outer packet mode classification, according to preparation technology's classification of clad material, has OVD, VAD and APVD method.Surrounding layer material purity is required is relatively low, and index distribution section is single, according to the difference of the difference of its outer packet mode or outsourcing material magazine content, selects the plug of suitable core bag proportioning.The manufacture of plug determines the performance of fiber products, is the gordian technique of preparing optical fiber.
Now with regard to common VAD method, do brief description.Figure 12 is the equipment schematic diagram of common double lamp VAD technique.As shown in figure 12; the first blowtorch 13 and the second blowtorch 14 are for spraying as hydrogen and oxygen are still not limited to the fuel such as hydrogen and oxygen; as argon gas but be not limited to the protection gas such as argon gas and as silicon tetrachloride, germanium tetrachloride but be not limited to the two for reacting the reactive material of the powder such as generation silicon-dioxide and germanium dioxide.Take silicon tetrachloride and oxyhydrogen flame as example, when the hydrogen that the first and second blowtorch 13,14 spray and oxygen fueled combustion, in the region near the first and second blowtorch 13,14 surfaces, the chemical substance SiCl spraying from the first and second blowtorch 13,14
4temperature sharply raise, when described chemical substance reaches and the temperature that surpasses this chemical reaction both about 1300 ℃ time, start to carry out oxidation as described below and hydrolysis reaction, thereby generate the oxide compound of silicon, granular SiO
2:
SiCl
4+ O
2→ SiO
2+ 2Cl
2(oxidation)
SiCl
4+ 2H
2o → SiO
2+ 4HCl (hydrolysis)
The particle of producing, along with the high-temperature gas that the deposition blowlamp from described sprays moves together, is then deposited on the relatively low prefabricated rods of temperature surface around by thermophoresis phenomenon, and this circle prefabricated rods thermograde has around caused this thermophoresis phenomenon.
In actual production process, by control, offer the first and second blowtorch 13, different types of reactive material of 14 makes the specific refractory power of plug 21 can be greater than the specific refractory power of covering 22, for example in the first blowtorch of deposition sandwich layer 21, add germanium tetrachloride, thereby realize sandwich layer 21 settled layer specific refractory poweres, be greater than covering 22.
In actual production process, by adjusting angle and the surrounding temperature of the particle beam that the first blowtorch and the second blowtorch eject, distribute, make powder sandwich layer 21 and covering 22 simultaneously toward axial and radial growth, by the laser in sandwich layer end or photographic equipment 41, implement to follow the tracks of the growth pattern of end, the pull rate of the lift end (not shown) of feedback control prefabricated rods.
With regard to low water peak single mode fiber preparation, with respect to OVD technique, tradition VAD technique is owing to there not being center target rod, in sintering and molten compression process, without consideration centre hole interface, be subject to the pollution of extraneous hydrogen containing foreign, be applicable to preparation low water peak, zero water peak fiber, but owing to there is no the support of target rod, the blowtorch in bosom needs to take into account the radial and axial rate of growth of powder in deposition process simultaneously, greatly improved the difficulty of technology controlling and process, be limited to equally the ratio of the radial and axial deposition of powder and the equilibrium relationship of collection effciency, greatly limited the sedimentation rate of VAD legal system for plug.Concrete take Figure 12 as example, powder from blowtorch 13 port injection out, by the direction of flow of powder and the adjusting of temperature field surrounding, formed the radial and axial growth of sandwich layer 21, sandwich layer 21 ends are hemispherical, in any case adjust angle powder, towards radial and axial growth, all can form a trim point, radially more also can be faster, in the actual production process at preformod of optical fiber with low water peak plug, covering and sandwich layer diameter than general control between 3 to 7, under more susceptible condition in 5 left and right, that is to say when sandwich layer 21 diameters reach 50mm, the diameter of covering 21 must reach 250mm, diameter reaches dehydration and sintering after certain size all can become problem, that is to say that sandwich layer rate of growth is radially restricted in actual applications, so axial growth also can be limited, thereby limited the sedimentation rate of prefabricated rods.
The following two pieces of patent analyses about VAD technique of take are example:
Chinese patent (CN 1952848A) " vapor axial deposition apparatus and gas phase axial deposition method " has been reported two blowtorch of a kind of employing, and blowtorch one is deposited powder on the end with the straight soot preforms of axis, thereby grows sandwich layer; Blowtorch two is at the outside of sandwich layer deposited powder, thereby grows covering.The first and second relative top temperatures of the soot preforms tail end detecting by Temperature Detector, and the relative minimum temperature between the two, set the relativeness between three, by analysis with the difference of setup parameter, control unit is by regulating blowtorch one, the gas flow of blowtorch two and composition, blowtorch position and soot preforms pulling speed are controlled the total quality of soot preforms.
United States Patent (USP) (US20120103023A1) " is manufactured the method for preform " and has been disclosed a kind of two blowtorch of taking, and blowtorch one is deposited powder on the end with the straight soot preforms of axis, thereby grows sandwich layer; Blowtorch two is deposited powder around sandwich layer, thereby grows covering.By CCD imager, detect the shape of soot preforms.By the difference between image analysis software analyzing and testing shape and setting shape, utilize Controlling System to regulate blowtorch gas flow and composition, the pulling speed of blowtorch position and soot preforms is controlled the total quality of soot preforms.
Such preparation method has following problem:
A) tail end of soot preforms had both needed to control temperature distribution, needed again to control shape, and process parameter control is complicated, and quantity-produced stability is not high;
According to soot rod profile feedback control pull rate and blowtorch powderject speed, powder density lack of homogeneity, easily because the weight and volume of prefabricated rods own constantly increases, causes Powder Rod cracking, and sedimentation rate is limited, and production efficiency reduces.
Summary of the invention
Complicated for above-mentioned control, low and the problem that has velocity limit of efficiency, the invention discloses a kind of novel VAD deposition method, the target rod of sandwich layer deposition is provided in whole deposition process, simplify the density in Powder Rod process of growth, geometrical dimension is controlled, and improves sedimentation effect and speed, provide a kind of reduction owing to being present in the method for the hydrogen containing foreign of centre hole in dehydration and sintering process, preparation can be used for the preform preparation method of low-water-peak fiber simultaneously.
For achieving the above object, the present invention solves the scheme that its technical problem takes and is: this method of preparing preformod of optical fiber with low water peak, and the method comprises following steps:
(a) use vapor axial method (VAD) to comprise SiO in target rod deposition
2, GeO
2deng powder.The delivery rate that comprises target rod pulling speed and different blowtorch by setting processing parameter, feed gaseous species and feed gas content, guarantee doping and geometrical homogenization.
(b) after body of powder has deposited on target rod, target rod is detached from body of powder, in body of powder, be formed centrally the centre hole along axis.
(c) tubulose body of powder one end is installed to handle sturcture, the other end is installed plug, then by handle sturcture, body of powder is sent into and in the process furnace that is filled with dehydrated air and heat-conducting gas, tubulose body of powder is dewatered and sinter tubular glass body into.
(d) welding of the tubular glass body two ends after sintering extension tube, this tubular glass body is placed in the liquid of hydrofluoric acid containing and corrodes, then clean is carried out in tubular glass body centre hole region and outside surface, then it is dry that the tubular glass body after cleaning is placed in to clean environment;
(e) dried tubular glass body is transferred in the electrothermal oven that contains oxygen and fluoro-gas and melts contracting, while melting contracting, need to vacuumize in one end of tubular glass body, the central zone interior orientation of gas after the condensation of tubular glass body flowed.In melting compression process, tubular glass body keeps, along axis rotation, in melting compression process, can to tubular glass body, stretching simultaneously.
(f) by the glass stick outsourcing covering after stretching or directly wire drawing become optical fiber, described optical fiber in 1383nm wavelength attenuation lower than 0.35dB/km.
Press such scheme, the optical fiber that the preform of preparation draws in the attenuation of 1383nm wavelength lower than 0.31dB/km
Press such scheme, in described step e, the OH mass content of tubular glass body central zone is less than 1ppb;
Press such scheme, the prefabricated rods vapor axial method in described step a adopts at least two deposition blowlamps.
Press such scheme, the first blowtorch in described step deposits on target rod, and the second blowtorch deposits on the first blowtorch deposited powder, and the 3rd blowtorch deposits on the second blowtorch deposited powder, so analogizes.
Press such scheme, the innermost layer for deposited powder layer in described vapor axial method is deposited on the target rod of the rotation that is contained in advance axis direction, and described target rod is glass or stupalith.
Press such scheme, in described step c, plug is the column glass material that hydroxyl mass content is less than 10ppm.
Press such scheme, in described step c, the dehydration of tubulose body of powder is carried out within containing one or more the atmosphere of mixed gas of chlorine, helium and oxygen in process furnace.
Press such scheme, described steps d comprises the extension tube that keeps original deposition initiating terminal, and excision deposition finishes the glass containing plug of end, finishes the welding of the glass place containing the plug extension tube of end in excision deposition.
Press such scheme, in described step e, tubular glass body is placed in the liquid of hydrofluoric acid containing and corrodes, and the thickness that in centre hole, tubulose vitreum is corroded is not less than 50 μ m.
Press such scheme, described tubular glass body corrosion thickness is not less than 500 μ m.
Press such scheme, the cleaning liquid deionized water in described step e.
Press such scheme, in described step e, before condensation, under heating environment, to the atmosphere of central zone and centre hole region glass, adopt fluoro-gas to carry out chemical corrosion, dehydration.
Press such scheme, the fluoro-gas adopting in described chemical corrosion, the step of dehydration is C
2f
6and O
2gas mixture.
Press such scheme, the hydroxyl matter mass content of described gas mixture requires to be less than 1ppm.
Press such scheme, the temperature of the process furnace in described step e is 1600 to 2200 degree, and process furnace translational speed is 10～80mm/min, and overpressure is that-100 pa are to+100 pa.
Compared with prior art, usefulness of the present invention is: this method properly distributed of preparing preformod of optical fiber with low water peak sintering, dehydration, the function that molten contracting stretches, possesses high sedimentation effect, sedimentation rate, control simple, the large-sized preformod of optical fiber with low water peak that is applicable to the various core bag ratios of preparation, greatly reduce the manufacturing cost of optical fiber, the VAD deposition method of Liao Dai center target rod is provided, greatly reduce core bag deposition geometrical dimension proportioning, geometrical homogenization, mix inhomogeneity difficulty, be suitable for many lamps plane SH wave, prepare various core bags how much and the large size prefabricated rod of refractive index structures.
accompanying drawing explanation:
Below in conjunction with accompanying drawing, the present invention is further described.
Fig. 1 is the process flow sheet that the present invention prepares the method for preformod of optical fiber with low water peak;
Fig. 2 is the deposition schematic diagram of the two blowtorch of axial gas phase method of the present invention (VAD);
Fig. 3 is the deposition schematic diagram of the many blowtorch of axial gas phase method of the present invention (VAD);
Fig. 4 be in the present invention end not with the dehydration of the body of powder of plug, sintering schematic diagram;
Fig. 5 is the dehydration of the body of powder of end band plug in the present invention, sintering schematic diagram;
Fig. 6 is the vitreum sectional view of sintering rear center direct polycondensation in the present invention;
Fig. 7 is the sintering rear center vitreum sectional view of condensation not in the present invention;
Fig. 8 is the schematic diagram extending again after the cutting of the two ends of Glass tubing after sintering in the present invention;
Fig. 9 corrodes schematic diagram after extending and corrode hydrogen desiccation in the present invention in electrothermal oven;
Figure 10 melts contracting stretching schematic diagram at electrothermal oven after extending and corrode hydrogen desiccation in the present invention;
Figure 11 is the attenuation spectrogram of pulling optical fiber preform in the present invention;
Figure 12 is the schematic diagram of common VAD equipment.
In figure: 10, centre hole; 11, axis; 12, body of powder; 13, the first blowtorch; 14, the second blowtorch; 15,16, blowtorch; 18, vitreum; 19 tubular glass bodies; 21, sandwich layer; 22,23,24, settled layer; 31, target rod; 32, extension tube; 33, plug; 34, transfer mechanism; 50, process furnace; 51, heating cavity; 61, electrothermal oven; 63, vacuum pump.
Embodiment
Below in conjunction with the drawings and the specific embodiments, describe the present invention:
A kind of method of preparing preformod of optical fiber with low water peak shown in Fig. 1, the method comprises following steps:
(a) use vapor axial method (VAD) to comprise SiO in target rod 31 depositions
2, GeO
2deng powder, wherein the first blowtorch 13 at target rod 31 outsides deposition sandwich layer 21, the second blowtorch 13 blowtorch such as grade in the peripheral deposition of sandwich layer, thereby grow covering.By setting processing parameter as the delivery rate of target rod pulling speed and different blowtorch, feed gaseous species and feed gas content, guarantee doping and geometrical homogenization;
(b) after body of powder 12 has deposited on target rod 31, target rod 31 is detached from body of powder 12, in body of powder 12, be formed centrally the centre hole 10 along axis 11;
(c) handle sturctures are installed in tubulose body of powder 12 one end, the other end is installed plug 33, then by handle sturcture, body of powder is sent into and in the process furnace 50 that is filled with dehydrated air and heat-conducting gas, tubulose body of powder 12 is dewatered and sinter tubular glass body 19 into.
(d) the 19 two ends welding extension tubes 32 of the tubular glass body after sintering, this tubular glass body 19 is placed in the liquid of hydrofluoric acid containing and corrodes, then clean is carried out in tubular glass body 19 centre hole regions and outside surface, then it is dry that the tubular glass body 19 after cleaning is placed in to clean environment;
(e) dried tubular glass body 19 is transferred in the electrothermal oven that contains oxygen and fluoro-gas and melts contracting, while melting contracting, need to vacuumize in one end of tubular glass body, the central zone interior orientation of gas after 19 condensations of tubular glass body flowed.In melting compression process, tubular glass body 19 keeps, along axis 11 rotations, in melting compression process, can to tubular glass body 19, stretching simultaneously;
(f) by the glass stick outsourcing covering after stretching or directly wire drawing become optical fiber, described optical fiber in 1383nm wavelength attenuation lower than 0.35dB/km.
Be different from common VAD method depositing operation, in the VAD method depositing operation providing in the present invention, in order to deposit the deposition of the first blowtorch 13 of sandwich layer, all on the target rod of a rotation, 31 carry out, Powder Rod need to be the second, the three or more blowtorch according to refractive index profile or sedimentation rate after the first layer from inside to outside successively.
Fig. 2 is the schematic diagram of provided by the invention pair of lamp VAD deposition method.As shown in Figure 2; the first blowtorch 13 and the second blowtorch 14 are for spraying as hydrogen and oxygen are still not limited to the inflammable gass such as hydrogen and oxygen; as argon gas but be not limited to the protection gas such as argon gas and as silicon tetrachloride, germanium tetrachloride but be not limited to the two for reacting the reactive material of the siliceous and germanium of the powder such as generation silicon-dioxide and germanium dioxide.The fluid that comprises silicon-dioxide and germanium dioxide particle that reaction generates is ejected into along on the target rod 31 of axis 11 rotations along flame direction, existence due to target rod 31, the collection effciency of powder on target rod 31 improves greatly, with respect to common VAD method, the collection effciency of powder is increased to 50～70% by 20～40%; VAD method as common in Figure 12 is by the variation of the geometrical dimension that is placed near laser sandwich layer 21 Powder Rod taperings or photographic equipment and measures in real time tapering or the temperature distribution that temperature sensing device is measured tapering in real time, the pulling speed of feedback control Powder Rod, thereby the diameter uniformity of control Powder Rod.Method provided by the invention can be cancelled this feedback control parts, by setting corresponding processing parameter, guarantees doping and geometrical homogenization.The fluid of the silica containing particle ejecting from the second blowtorch 14 be take sandwich layer 21 and is deposited and grow as target, existence due to center target rod 31, greatly promoted the sedimentation rate of sandwich layer 21, in actual applications can be at outer increase the second blowtorch 14, the three of the first blowtorch 13 or more blowtorch further to improve the whole sedimentation rate of plug.
If Fig. 3 is the schematic diagram of the VAD method deposition of a kind of many lamps in the present invention, according to the silicon-dioxide of setting component, the powder such as germanium dioxide are by the first blowtorch 13, the second blowtorch 14, blowtorch 15 and 16 sprays and is deposited as corresponding settled layer 22, 23, 24, each settled layer 22 wherein, 23, 24Yu center target rod 31 is concentric, by increasing the number of blowtorch or the reactant flow in single blowtorch, can improve the sedimentation rate of body of powder 12, by silicon tetrachloride in each lamp of harmonizing, the content of germanium tetrachloride and other dopants can obtain the prefabricated rods of more refractive index profiles.
After the body of powder of target size and doping has deposited on target rod 31, target rod 31 is detached from body of powder 12, as shown in Figure 4, having there is centre hole 10 in the axle center that removes the body of powder 12 of center target rod 31, and extension tube 32 is placed on to the transfer mechanism that moves up and down and rotate 34 that is placed in dehydrothermal stove 50 tops for controlling the top extension tube 32. of body of powder 12.By transfer mechanism 34, body of powder 12 is transported in process furnace 50, process furnace 50 is risen to 1000 to 1200 degree, in heating cavity 51, inject the gas for dehydrating and removing impurities and heat conduction simultaneously, this gas is the gas mixture of chlorine and helium preferably, rotate and move up and down body of powder 12, by wherein hydrogen containing foreign and other impurity are removed by chemical process under the temperature condition of 1000 to 1200 degree, then by temperature increase to the 1500 degree left and right in cavity, sinter powder porous loosening body into vitreum 18.
As Fig. 5 is preferably in the end of body of powder 12 in the present invention, the plug 33 that installation can match with centre hole 10, described plug 33 is preferably the vitreum that hydroxy radical content is less than 10 ppm, near glassy zone described centre hole 10 is the position in photoconductive fiber bosom, most of light is at this regional spread, the purity in this region is the strongest on the optical property impact of optical fiber, on the other hand, in the high-temperature process of dehydration and sintering, if plug 33 is not installed endways, the interior gas flow rate of centre hole 10 and flow are obviously greater than the situation that plug 33 is installed, may cause the impurity in cavity to adhere to, more serious is, the chlorine gas environment of excessive temperature and high density causes volatilization and the oxidation of this position germanium dioxide, affecting refractive index profile distributes, increase the difficulty of subsequent disposal.
In production application, take that to have the technique of centre hole 10 after this deposition of OVD and PCVD be example, main hydrogen containing foreign be before centre hole 10 condensations and condensation course in water in environment be diffused into this region, such as the tubular glass body 19 containing centre hole 10 is being transferred in the process of condensation stove, the gas that contains moisture in environment is diffused into centre hole 10 regions, the optical fiber that made prefabricated rods draws has large absorption peak at 1383nm wave band, cannot prepare low-water-peak fiber.Research surface: in center bore region is positioned over containing hydrogen atmosphere, in air, the water (H of physical adsorption
2o) and the water of chemisorption (OH) in centre hole region, be bonded to rapidly on glass, moisture content is higher, storage period, longer this absorption was stronger, and how shortly no matter had this storage period, and the hydrogen containing foreign of its diffusion enough causes optical fiber water peak to exceed standard.
In the present invention, as shown in Figure 6, in having the body of heater of dehydration and sintering function, by providing negative pressure slightly in centre hole 10 regions, be preferably less than-100pa of this micro-negative pressure directly burns till the vitreum 18 of center condensation by body of powder 12 in this atmosphere.Then redraw into as required target geometrical dimension, its optical fiber of preparing meets the requirement of low-water-peak fiber at 1383nm.
In the present invention, the preferential scheme of selecting is in sintering oven, be sintered directly into as the tubular glass body 19 in Fig. 7, this scheme has been taken into account the demand that large size plug posterior drawing is processed, to melt contracting function and be placed on this step, do not increasing under the prerequisite of technical process, inventing the method that process in centre hole 10 regions again.The method providing as Fig. 4, solved between central section containing the problem of hydroxyl impurity, but volatilization and the oxidation in being greater than the dehydration of 1000 degree and sintering process of this region germanium dioxide reduces the centre line zone specific refractory power of prefabricated rods after sintering, formation center lower limit, affects the optical property of optical fiber.In the present invention, first sinter tubular glass body 19 into, in follow-up docking cleaning process, increase hydrofluoric acid corrosion, in drawing process, increase the method that fluoro-gas dewaters and corrodes, remove moisture impurity and this region ge content part on the low side in centre hole 10 and inner boundary region.
As shown in Figure 8, after body of powder 12 sinters tubular glass body 19 into, in its opposed distal end extension tube 32, described Glass tubing 32 is preferably hydroxy radical content and is less than 10ppm, by two ends respectively the tubular glass body 19 of Glass tubing be positioned in the solution of hydrofluoric acid containing cleaning corroded in barred body interface, centre hole 10 inner wall corrosion thickness are greater than 50um, optimum state is to be greater than 0.5mm, after corrosion, tubular glass body 19 is cleaned, optimum state, for using washed with de-ionized water, is then placed in the barred body after cleaning the environment inner drying of dry gas.
As Fig. 9,10 is placed in electrothermal oven 61 by tubular glass body 19, in one end of tubular glass body 19, be filled with fluoro-gas, this gas is preferably the gas mixture of oxygen and fluoro-gas, and this fluoro-gas is C preferably
2f
6the tubular glass body 19 that is filled with gas is heated in electrothermal oven, Heating temperature is greater than 1500 degree, making hydrous matter in the interior environment of centre hole 10 and centre hole 10 regions include water section reacts away with freonll-11, other one section at tubular glass body 19 is vacuum pump 63, makes flowing of gas orientation, reaction product is detached to centre hole 10 by pump 63 simultaneously.
According to setting program to centre hole 10 region removal of impurities and corrosion after, as shown in figure 10, the temperature of electrothermal oven 61 is risen to 2000 degree left and right, continue to be less than at vacuum pump 63 end positions the negative pressure slightly of-100 pa, progressively by centre hole 10 condensations, in order to guarantee that centre hole 10 region glass parts have good axial symmetry, whole molten compression process keeps tubulose vitreum 19 along axis 11 rotations.In molten compression method of the present invention, can to solid, stretch simultaneously, be drawn into the tubular glass body 19 of target external diameter.
Molten the contracing of appeal is stretched to the glass stick of target external diameter, according to the core bag diameter proportion of the final glass optical fiber corresponding covering of outsourcing again, described surrounding layer can be also OVD by tiretube process, the outsourcing of the method such as VAD or APVD Direct precipitation, prefabricated rods after outsourcing is drawn into the glass optical fiber of demand external diameter, owing to having taked the scheme optimum in contracting and the present invention that directly melts provided by the invention in dehydration-sintering furnace, before molten contracting and in the molten process stretching that contracts, increase dehydrogenation technique, avoided centre hole layer to contain higher hydroxyl.The hydroxy radical content in final this region is less than 1ppb, and the optical fiber drawing has the absorption peak that is less than 0.31dB/km near 1383nm wavelength.
Figure 11 is for adopting the bright method providing of this law to prepare prefabricated rods and the attenuation spectrogram of the optical fiber that is drawn into, wherein 91 for adopting the VAD deposition method that this law provides in bright but in follow-up sintering process, do not carry out the attenuation spectrum of the prepared optical fiber of chemical process dehydrogenation, 92 first corrode cleaning-drying with hydrofluoric acid for what provide in employing invention, then at the preform containing condensation in freonll-11 air ring border, be drawn into the attenuation spectrogram of optical fiber, 93 for the VAD deposition method providing in invention the also attenuation spectrogram of the preform of sintering that dewaters in dehydration-sintering furnace are provided.
Below by specific embodiment, the present invention is described in further detail; Below four embodiment comprised respectively direct polycondensation in sintering oven and prepared G652 preform, two lamps deposit and pass through hydrofluoric acid, freonll-11 corrosion is molten contracting stretching preparation G652 preform then, three lamps deposit and pass through hydrofluoric acid, and freonll-11 corrosion is the embodiment of the rear preparation of molten contracting stretching G657 preform then.
In VAD method deposition, use diameter for 8mm ceramic target rod, adopt two blowtorch to deposit respectively sandwich layer and covering powder bed diameter to 55mm and 200mm, its center core layer is SiO
2with GeO
2mixture, covering is SiO
2powder, body of powder mean density is 0.55gram/cm
3, body of powder length is 1000mm.After deposition finishes, remove ceramic target rod from body of powder, at its end, external diameter being installed is 8.1mm, the solid glass rod that length is 90mm, and this solid bar is the high purity quartz rod that hydroxyl mass content is less than 1ppm.Then body of powder is transferred to the delivery platform of dehydration-sintering furnace, prefabricated rods is put in dehydration-sintering furnace from top to bottom, volatilization for fear of center germanium dioxide doped layer causes that the center of section is sagging, poise the large size design that sandwich layer sedimentation diameter reaches 55mm and dilute sagging impact, for fear of the too high glass inner bag softening transform causing in sintering oven of furnace temp when the centre hole condensation, in this sintering oven, do not use glass inner bag, near hot-zone, adopt graphite inner bag.
Hot-zone temperature is risen to 1100 ℃, in the bottom of sintering oven, be filled with 40SLPM helium, 5SLPM chlorine, body of powder is passed through the hot-zone of sintering oven from top to bottom with 400mm/min speed, complete after above-mentioned dehydration procedure, sintering oven temperature is increased to 1500 ℃, maintain chlorine and helium atmosphere flow is constant, body of powder is entered overheated zone from bottom to top with the speed of 7mm/min, realize the sintering of body of powder, after finishing, sintering circuit extends the negative pressure that rod provides centre hole 100pa on body of powder top, hot-zone temperature is increased to 1900 ℃, helium gas flow is reduced to 10SLPM, chlorine gas flow is reduced to 2SLPM, by sintered compact with 5mm/min speed from top to bottom through overheated zone, condensation center hole.Solid bar after condensation is stretched to external diameter 41mm, adopts the outsourcing of OVD method to 150mm solid bar, wire drawing optical fiber result is as table 1:
| Cladding diameter | 1310nm attenuation | 1383nm attenuation | 1550nm attenuation |
| 125μm | 0.338dB/km | 0.291dB/km | 0.196dB/km |
embodiment 2
In VAD method deposition, use diameter for 8mm ceramic target rod, adopt two blowtorch to deposit respectively sandwich layer and covering powder bed diameter to 18mm and 220mm, its center core layer is SiO
2with GeO
2mixture, covering is SiO
2powder, body of powder mean density is 0.55gram/cm
3, body of powder length is 1000mm.After deposition finishes, remove ceramic target rod from body of powder, at its end, external diameter being installed is 8.1mm, the solid glass rod that length is 90mm, and this solid bar is the high purity quartz rod that hydroxyl mass content is less than 1ppm.Then body of powder is transferred to the delivery platform of dehydration-sintering furnace, prefabricated rods is put in the dehydration-sintering furnace that cavity liner is Glass tubing from top to bottom.
Hot-zone temperature is risen to 1100 ℃, in the bottom of sintering oven, be filled with 40SLPM helium, 5SLPM chlorine, body of powder is passed through the hot-zone of sintering oven from top to bottom with 400mm/min speed, complete after above-mentioned dehydration procedure, sintering oven temperature is increased to 1500 ℃, maintain chlorine and helium atmosphere flow is constant, body of powder is entered overheated zone from bottom to top with the speed of 7mm/min, realizes the sintering of body of powder; Then by the Glass tubing opposed distal end extension tube after sintering, molectron after docking is corroded and to centre hole aperture, increases 1mm with hydrofluoric acid, the gas inner drying purging at drying nitrogen 12 hours, then in electrothermal oven, first use the temperature of 1700 ℃, in center internal control, be filled with the freonll-11 (C of 1SLPM oxygen and 0.5SLPM
2f
6), body of heater passes through vitreum 18 vertically with the speed of 30mm/min, at one end by vacuum pump, applies the negative pressure of 100pa after etching, and furnace temperature is risen to 2000 degree simultaneously, with the translational speed of 15mm/min, Glass tubing is carried out to condensation.The prefabricated rods of condensation is drawn into optical fiber in fiber drawing furnace, and optical fiber result is as table 2:
| Cladding diameter | 1310nm attenuation | 1383nm attenuation | 1550nm attenuation |
| 125μm | 0.333dB/km | 0.308dB/km | 0.192dB/km |
embodiment 3
In VAD method deposition, use diameter for 8mm ceramic target rod, adopt three blowtorch to deposit respectively sandwich layer, the first covering and the second covering powder bed diameter be to 65mm, 160mm and 280mm, and its center core layer is SiO
2with GeO
2mixture, covering is SiO
2powder, body of powder mean density is 0.55gram/cm
3, body of powder length is 800mm.After deposition finishes, remove ceramic target rod from body of powder, at its end, external diameter being installed is 8.1mm, the solid glass rod that length is 90mm, and this solid bar is the high purity quartz rod that hydroxyl mass content is less than 1ppm.Then body of powder is transferred to the delivery platform of dehydration-sintering furnace, prefabricated rods is put in the dehydration-sintering furnace that cavity liner is Glass tubing from top to bottom.
Hot-zone temperature is risen to 1100 ℃, in the bottom of sintering oven, be filled with 40SLPM helium, 5SLPM chlorine, body of powder is passed through the hot-zone of sintering oven from top to bottom with 400mm/min speed, complete after above-mentioned dehydration procedure, sintering oven temperature is increased to 1500 ℃, maintain chlorine and helium atmosphere flow is constant, body of powder is entered overheated zone from bottom to top with the speed of 7mm/min, realizes the sintering of body of powder; Then by the Glass tubing opposed distal end extension tube after sintering, molectron after docking is corroded and to centre hole aperture, increases 1mm with hydrofluoric acid, the light body inner drying purging at drying nitrogen 12 hours, then in electrothermal oven, first use the temperature of 1700 ℃, in center internal control, be filled with the freonll-11 (C of 1SLPM oxygen and 0.5SLPM
2f
6), body of heater passes through vitreum 18 vertically with the speed of 30mm/min, at one end by vacuum pump, applies the negative pressure of 100pa after etching, and furnace temperature is risen to 2000 ℃ simultaneously, with the translational speed of 12mm/min, Glass tubing is carried out condensation and is stretched.By preform bar stretching external diameter, be 43mm, it is that 46mm external diameter is the sleeve pipe that 150mm hydroxyl mass content is less than 1ppm that 43mm external diameter plug is placed in to internal diameter, directly melts contracting wire drawing to 125um external diameter on wire-drawer-tower.Its optical fiber result is as table 3:
| Cladding diameter | 1310nm attenuation | 1383nm attenuation | 1550nm attenuation |
| 125μm | 0.332dB/km | 0.295dB/km | 0.189dB/km |
embodiment 4
This embodiment is for adopting the preparation method of the bend insensitive fiber prefabricated rods of three blowtorch.
In VAD method deposition, use diameter for 8mm ceramic target rod, adopt three blowtorch to deposit respectively sandwich layer, the first covering and the second covering powder bed diameter be to 45mm, 62mm and 180mm, and its center core layer is SiO
2with GeO
2mixture, the first covering is SiO
2powder, the second covering is fluorine-containing SiO
2powder, body of powder mean density is 0.5gram/cm
3, body of powder length is 800mm.After deposition finishes, remove ceramic target rod from body of powder, at its end, external diameter being installed is 8.1mm, the solid glass rod that length is 90mm, and this solid bar is the high purity quartz rod that hydroxyl mass content is less than 1ppm.Then body of powder is transferred to the delivery platform of dehydration-sintering furnace, prefabricated rods is put in the dehydration-sintering furnace that cavity liner is Glass tubing from top to bottom.
Hot-zone temperature is risen to 1100 ℃, in the bottom of sintering oven, be filled with 40SLPM helium, 5SLPM chlorine, body of powder is passed through the hot-zone of sintering oven from top to bottom with 400mm/min speed, complete after above-mentioned dehydration procedure, sintering oven temperature is increased to 1450 ℃, maintain chlorine and helium atmosphere flow is constant, body of powder is entered overheated zone from bottom to top with the speed of 8mm/min, realizes the sintering of body of powder; Then by the Glass tubing opposed distal end extension tube after sintering, molectron after docking is corroded and to centre hole aperture, increases 1mm with hydrofluoric acid, the cavity inner drying purging at drying nitrogen 12 hours, then in electrothermal oven, first use the temperature of 1700 ℃, in center internal control, be filled with the freonll-11 (C of 1SLPM oxygen and 0.5SLPM
2f
6), body of heater passes through vitreum 18 vertically with the speed of 30mm/min, at one end by vacuum pump, applies the negative pressure of 100pa after etching, and furnace temperature is risen to 2000 ℃ simultaneously, with the translational speed of 20mm/min, Glass tubing is carried out condensation and is stretched.To 41mm, then 41mm external diameter plug is adopted the outsourcing of OVD method to 150mm solid bar preform bar stretching external diameter, wire drawing optical fiber result is as table 4:
This method properly distributed of preparing preformod of optical fiber with low water peak sintering, dehydration, the function that molten contracting stretches, possesses high sedimentation effect, sedimentation rate, control simple, the large-sized preformod of optical fiber with low water peak that is applicable to the various core bag ratios of preparation, greatly reduce the manufacturing cost of optical fiber, the VAD deposition method of Liao Dai center target rod is provided, greatly reduce core bag deposition geometrical dimension proportioning, geometrical homogenization, mix inhomogeneity difficulty, be suitable for many lamps plane SH wave, prepare various core bags how much and the large size prefabricated rod of refractive index structures.
It is emphasized that: be only preferred embodiment of the present invention above, not the present invention is done to any pro forma restriction, any simple modification, equivalent variations and modification that every foundation technical spirit of the present invention is done above embodiment, all still belong in the scope of technical solution of the present invention.
Claims (16)
1. a method of preparing preformod of optical fiber with low water peak, the method comprises following steps:
(a) use vapor axial method (VAD) to comprise SiO in the upper deposition of target rod (31)
2, GeO
2deng powder, by setting processing parameter, comprise the delivery rate of target rod (31) pulling speed and different blowtorch, feed gaseous species and feed gas content, guarantee doping and geometric proportion and homogeneity;
(b) after body of powder (12) has deposited on target rod (31), target rod (31) is detached from body of powder (12), in body of powder (12), be formed centrally the centre hole (10) along axis (11);
(c) handle sturcture is installed in tubulose body of powder (12) one end, the other end is installed plug (33), then by handle sturcture, body of powder is sent into and in the process furnace (50) that is filled with dehydrated air and heat-conducting gas, tubulose body of powder (12) is dewatered and sinter tubular glass body (19) into;
(d) welding of tubular glass body (19) two ends after sintering extension tube (32), this tubular glass body (19) is placed in the liquid of hydrofluoric acid containing and corrodes, then clean is carried out in tubular glass body (19) centre hole (10) region and outside surface, then it is dry that the tubular glass body (19) after cleaning is placed in to clean environment;
(e) dried tubular glass body (19) is transferred in the electrothermal oven that contains oxygen and fluoro-gas and melts contracting, while melting contracting, need to vacuumize in one end of tubular glass body, the central zone interior orientation of gas after tubular glass body (19) condensation flowed, in melting compression process, tubular glass body (19) keeps, along axis (11) rotation, in melting compression process, can to tubular glass body (19), stretching simultaneously;
(f) by the glass stick outsourcing covering after stretching or directly wire drawing become optical fiber, described optical fiber in 1383nm wavelength attenuation lower than 0.35dB/km.
2. the method for preparing preformod of optical fiber with low water peak according to claim 1, is characterized in that: the optical fiber of described step f in the attenuation of 1383nm wavelength further lower than 0.31dB/km.
3. prepare as claimed in claim 1 the method for preformod of optical fiber with low water peak, it is characterized in that: in described step e, the OH mass content of tubular glass body (19) central zone is less than 1ppb.
4. the method for preparing preformod of optical fiber with low water peak according to claim 1, is characterized in that: the prefabricated rods vapor axial method in described step a adopts at least two deposition blowlamps.
5. the method for preparing preformod of optical fiber with low water peak according to claim 4, it is characterized in that: during deposition, the first blowtorch (13) deposits on target rod, the second blowtorch (14) deposits on the first blowtorch (13) deposited powder, the 3rd blowtorch deposits on the second blowtorch deposited powder, so analogizes.
6. the method for preparing preformod of optical fiber with low water peak according to claim 1, it is characterized in that: the innermost layer for deposited powder layer in described vapor axial method is deposited on the target rod (31) of the rotation that is contained in advance axis (11) direction, and described target rod (31) is glass or stupalith.
7. the method for preparing preformod of optical fiber with low water peak according to claim 1, is characterized in that: plug in described step c (33) is less than the column glass material of 10ppm for hydroxyl mass content.
8. the method for preparing preformod of optical fiber with low water peak according to claim 1, is characterized in that: in described step c, the dehydration of tubulose body of powder (12) is carried out in process furnace in one or more the atmosphere of mixed gas that contains chlorine, helium and oxygen.
9. the method for preparing preformod of optical fiber with low water peak according to claim 1, it is characterized in that: described steps d comprises the extension tube (32) that keeps original deposition initiating terminal, excision deposition finishes the glass containing plug (33) of end, finishes the welding of the glass place containing plug (33) extension tube (32) of end in excision deposition.
10. the method for preparing preformod of optical fiber with low water peak according to claim 1, it is characterized in that: in described step e, tubular glass body (19) is placed in the liquid of hydrofluoric acid containing and corrodes, and the thickness that the interior tubulose vitreum of centre hole (10) (19) is corroded is not less than 50 μ m.
11. according in the corrosion step described in claims 10, it is characterized in that: described tubular glass body (19) corrosion thickness is not less than 500 μ m.
12. methods of preparing preformod of optical fiber with low water peak according to claim 1, is characterized in that: the cleaning liquid in described step e is deionized water.
13. methods of preparing preformod of optical fiber with low water peak according to claim 1, it is characterized in that: in described step e, before condensation, under heating environment, to the atmosphere of central zone and centre hole (10) region glass, adopt fluoro-gas to carry out chemical corrosion, dehydration.
14. methods of preparing preformod of optical fiber with low water peak according to claim 13, is characterized in that: described fluoro-gas is C
2f
6and O
2gas mixture.
15. methods of preparing preformod of optical fiber with low water peak according to claim 14, is characterized in that: the hydroxyl matter mass content of described gas mixture requires to be less than 1ppm.
16. methods of preparing preformod of optical fiber with low water peak according to claim 1, it is characterized in that: the temperature of the process furnace in described step e is 1600 to 2200 degree, process furnace translational speed is 10～80mm/min, and overpressure is that-100 pa are to+100 pa.
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| CN104355532A (en) * | 2014-10-30 | 2015-02-18 | 江苏通鼎光电股份有限公司 | Optical fiber preform manufacturing method |
| CN105347666A (en) * | 2015-11-30 | 2016-02-24 | 中天科技精密材料有限公司 | Manufacturing method of low-loss optical fiber preformed rod |
| CN106219961A (en) * | 2016-08-05 | 2016-12-14 | 长飞光纤光缆股份有限公司 | A kind of VAD prepares the device and method of preform |
| WO2019036925A1 (en) * | 2017-08-23 | 2019-02-28 | 成都富通光通信技术有限公司 | Optical fiber and preparation method therefor |
| CN110221383A (en) * | 2019-07-12 | 2019-09-10 | 杭州金星通光纤科技有限公司 | A kind of single mode optical fiber and its manufacturing method |
| CN110546112A (en) * | 2017-03-29 | 2019-12-06 | 普睿司曼股份公司 | Method and apparatus for drying and consolidating optical fiber preforms |
| CN116081938A (en) * | 2023-02-17 | 2023-05-09 | 长飞光纤光缆股份有限公司 | Blowtorch for external vapor deposition method |
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| CN110221383A (en) * | 2019-07-12 | 2019-09-10 | 杭州金星通光纤科技有限公司 | A kind of single mode optical fiber and its manufacturing method |
| CN110221383B (en) * | 2019-07-12 | 2023-07-07 | 杭州金星通光纤科技有限公司 | Single-mode optical fiber and manufacturing method thereof |
| CN116081938A (en) * | 2023-02-17 | 2023-05-09 | 长飞光纤光缆股份有限公司 | Blowtorch for external vapor deposition method |
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