CN101052596A - Fibre-optical with high wide-band and manufacturing method thereof - Google Patents
Fibre-optical with high wide-band and manufacturing method thereof Download PDFInfo
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- CN101052596A CN101052596A CNA2005800336083A CN200580033608A CN101052596A CN 101052596 A CN101052596 A CN 101052596A CN A2005800336083 A CNA2005800336083 A CN A2005800336083A CN 200580033608 A CN200580033608 A CN 200580033608A CN 101052596 A CN101052596 A CN 101052596A
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/0253—Controlling or regulating
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0288—Multimode fibre, e.g. graded index core for compensating modal dispersion
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03605—Highest refractive index not on central axis
- G02B6/03611—Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Abstract
This invention relates to a novel protein, termed INSP152, herein identified as a secreted protein, in particular, as a MAM domain containing protein and to the use of this protein and nucleic acid sequence from the encoding gene in the diagnosis, prevention and treatment.
Description
Technical field
The present invention relates to have the manufacture method and the multimode optical fibers of the multimode optical fibers of high bandwidth, particularly relate to the method for making high-bandwidth multi-mode fiber by the measuring technology of index distribution.
Background technology
The optical fiber light-wave communication system is being played the part of important role in the voice and data transmission.The optical fiber that is used in the communication system can be single-mode fiber or multimode optical fibers.The present invention relates generally to the method for making multimode optical fibers.However, the method disclosed in the present also can be used to make single-mode fiber.
Multimode optical fibers comprises with the sandwich layer of whole signal limitations with around the covering of sandwich layer.Usually, be inserted with the blocking layer between meeting between sandwich layer and the covering.Multimode optical fibers is drawn by prefabricated rods and forms, this prefabricated rods can be by different technology processing, such as the chemical Vapor deposition process (MCVD) of improvement, Plasma Enhanced Chemical Vapor Deposition (PECVD) (PCVD), outside chemical Vapor deposition process (OVD), vapour phase axial deposition technique (VAD) or the like.
The communication performance of optical fiber mainly determines by light loss or decay and by chromatic dispersion.Light loss causes that by absorption, scattering, bad geometrical shape or textural defect and chromatic dispersion the tailing effect that these have caused light pulse causes noise.In the multimode optical fibers, signal dispersion causes owing to chromatic dispersion and intermode dispersion.Chromatic dispersion is because the change of refractive of the different wave length that causes of material itself, and intermode dispersion is because the light path difference of different transmission mode.Chromatic dispersion is expressed as the fiber bandwidth of per unit length or the Maximum Bit Rate of per unit length.
By design optical fiber, make it to have the index distribution of radial variations in core region, can reduce intermode dispersion.The big or small known of specific refractory power (n) is the function of the radius (r) from fiber optic hub, as following equation 1:
n(r)＝n
1(1-2Δ(r/a)
α)
1/2 (1)
n(r)＝n
2(1-2Δ)
1/2
Wherein, n
1The specific refractory power at expression sandwich layer center; n
2The specific refractory power of expression covering, α represents the sandwich layer shape index, and Δ represents refractive index contrast, shown in equation 2:
Δ＝(n
1-n
2)/n
1 (2)
Have been found that the multimode optical fibers bandwidth depends primarily on the value of α.Therefore, the distribution shape of the sandwich layer of graded fiber is parabola shaped, and can obtain higher bandwidth when α gets 1.9～2, and this depends on wavelength.This discovery is plotted in 43 pages of Figure 34 of " Optical FiberCommunications vol.1, Fiber Fabrication, Academic Press Inc., 1985 ,-Tingye Li ".The figure illustrates when the value of α less than 1.9 or greater than 2 the time, the bandwidth of multimode optical fibers will be less than 500MHzKm.Equal 2 (1-Δs) if the α value is chosen as, wherein Δ is the refractive index contrast between sandwich layer and the covering, and the bandwidth of so much mode fiber will be higher.
Therefore, make the α value reach this value or be in maximum value between 1.9～2.0, will make the bandwidth maximization of multimode optical fibers.The above results has caused the development of the multimode optical fibers of present disclosed method and manufacturing.
Prior art U.S. Patent No. 4,286,979 discloses a kind of manufacturing and has had the method for improving intermode dispersion and producing the multimode optical fibers of high bandwidth.This method comprises the differential mode delay measuring technology, thereby optimizes chromatic dispersion by suitable refractive index structures.According to this technology, utilize single-mode fiber that light is injected multimode optical fibers, wherein the footpath of single-mode fiber is upwards consistent with the multimode optical fibers shape.In this method, the optical fiber of manufacturing is carried out differential mode delay measure, the refractive index structures of the optical fiber of Zhi Zaoing is designed to minimize differential mode delay subsequently.This optical fiber of making subsequently adopts this technology to measure subsequently again, and therefore the radial refractive index gradient changes once more.Therefore, the main drawback of this method is, it is applicable to the optical fiber after the manufacturing rather than makes in the process of light, that is to say, this method is not suitable for as in the production line manufacturing processed, can not make this technical efficiency higher, improve or the control manufacturing process to improve throughput and economic benefit.
The main limitation of existing method is that technical benefits is subjected to be difficult to the restriction that excites module of precognition.In this method, single-mode fiber need have makes the characteristic of having only limited submodule group to excite in multimode optical fibers.This restriction is because it depends on exciting of submodule group, that is to say, it depends on the differential mode delay that adopts single-mode fiber to excite and measures.
Another limitation of existing method is that its makes the position that changes be in the optical fiber radially 0.1 micron of position.The corresponding layer of radial position of determining optical fiber measurement may cause determining the correctly variation of layer position.
Have been found that utilizing prior art is 0.1 micron to the resolving power of optical fiber measurement, this is more much lower than required resolving power.In addition, as mentioned above, according to existing method, specific refractory power [RI] be can not determine before stretching optical fiber in the local variation that sandwich layer distributes.Optical fiber after the stretching may not meet required bandwidth, therefore causes the optical fiber waste product.
In addition, existing method also requires to utilize the refractive index distribution structure of the analysis of differential mode delay device with the optical fiber of house of correction manufacturing except requiring to utilize profile analysis instrument refractive index distribution measuring.Therefore, this method needs extra equipment and skilled manpower, has increased the cost of making.The operation increase of manufacturing process has also increased the time of processing.
Necessity of the present invention
Therefore, be necessary to study a kind of method of processing multimode optical fibers,, that is to say, can be used as the production line manufacturing process even if this method also can be improved index distribution in processing optical fiber process.Equally, also be necessary to study a kind of method that need not the exciton module, this method still can make to change and is in about 5 microns of the sandwich layer radial position.Also be necessary to study a kind of method of correcting index distribution, this method need not to use the differential mode delay device analysis, thereby has improved economic benefit.
Summary of the invention
As mentioned above, the α value has influenced the bandwidth value of multimode optical fibers.In the time of between α gets about 1.9～2.0, bandwidth is higher.Therefore, the bandwidth maximization that the α value is in to make multimode optical fibers between 1.9～2.0.Therefore method of the present invention and the optical fiber of producing are are in view of the above researched and developed.
Be surprised to find that,, will show the local variation of the specific refractory power of each settled layer when the specific refractory power (RI) of each settled layer when radially layering is measured.Equally also find,, just after making preform, measure, the scrap rate of light finished product will be reduced if specific refractory power is to measure before stretching optical fiber.The ordinary method that comprises the differential mode delay technology can provide resolving power probably to be 0.1 micron.Yet before the stretching optical fiber, radially layering refractive Index Distribution Measurement makes its resolving power be about 0.02 micron.Therefore, among the embodiment, the present invention relates to a kind of manufacture method with multimode optical fibers of high bandwidth, comprise the making of preform, prefabricated rods is made according to sandwich layer specific refractory power, sandwich layer diameter, sandwich layer α value, cladding index and the cladding diameter of utilizing the prefabricated rods analyser to measure, to determine the profile of prefabricated rods, it is characterized in that:
A) according to the prefabricated rods profile of sandwich layer, determine the sandwich layer index distribution at each settled layer;
B), determine the peak value and the valley of index distribution along the prefabricated rods radial direction according to index distribution from the sandwich layer that step a) obtained;
C) every layer index distribution is determined by the center line average of peak value that step b) obtained and valley;
D) according to the specific refractory power of each settled layer that step c) obtained, radially determine layering α;
E) the layering α that obtains according to step d) calculates the layering time-delay;
F) determine correction factor according to the difference of desirable layering mould time-delay and the time-delay of actual mould, to obtain every layer of required α index distribution;
G) based on described corrected parameter, by changing reaction parameter,, obtain this required α index distribution such as doping agent flow or concentration or temperature of reaction or the like, with the formation prefabricated rods, and then form optical fiber with high bandwidth.
Therefore, in another embodiment, the present invention relates to a kind of manufacture method that has the multimode optical fibers of high bandwidth, this method comprises according to the prior art for preparing preform, prefabricated rods is made according to the sandwich layer specific refractory power of utilizing the prefabricated rods analyser to measure, sandwich layer diameter, sandwich layer α value, cladding index and cladding diameter preparation, to determine the profile of prefabricated rods, it is characterized in that:
A), determine the index distribution of sandwich layer at each settled layer according to the prefabricated rods profile of sandwich layer;
B) index distribution of the sandwich layer that obtains according to step a is along the peak value and the valley of radially determining index distribution of prefabricated rods;
C) peak value that is obtained according to step b and the center line average of valley are determined every layer index distribution;
D) index distribution of each settled layer that is obtained according to step c is radially determined layering α;
E) determine correction factor according to the difference of desirable layering α and actual layering α, to obtain every layer of required layering α index distribution;
F) based on correction factor, by changing reaction parameter, for example doping agent flow or concentration or temperature of reaction or the like obtain this required layering α specific refractory power, with the formation prefabricated rods, and then the optical fiber of formation high bandwidth.
Purpose of the present invention
Main purpose of the present invention provides a kind of manufacture method of multimode optical fibers of high bandwidth, and wherein Fabrication parameter can be in the production line correction, and promptly before optical fiber was made, construction of indexes can be in the production line correction, with the maximization bandwidth of an optical fiber.
Another object of the present invention provides a kind of method of making multimode optical fibers, and this method can be used as the production line manufacture method, makes this technical efficiency higher, and improves or control this manufacture method, to improve output and economic benefit.
In addition, another object of the present invention provides a kind of manufacture method of multimode optical fibers, and wherein exciting of submodule group just do not depended in the restriction of the module that is not stimulated of the effect of this method.
In addition, another object of the present invention provides a kind of manufacture method of multimode optical fibers, wherein changes to be in 0.02 micron of optical fiber radial position.
Therefore, the manufacture method that the objective of the invention is to a kind of multimode optical fibers of full disclosure, wherein the localized variation that specific refractory power [RI] distributes in the plug can be determined before stretching optical fiber, and correction factor can be in production line application, thus the high bandwidth of obtaining and avoid the optical fiber of waste product generation.
A further object of the invention provides a kind of manufacture method of multimode optical fibers, and this method need not to utilize the index distribution of differential mode delay device with the optical fiber of correction manufacturing, avoids required extra means and skilled manpower, and production cost is reduced.The present invention be advantageous in that the production time of having saved optical fiber, improved the throughput of factory.
Other purposes of the present invention, advantage and preferred embodiment become more clearly in following description with in conjunction with the accompanying drawings, and accompanying drawing does not constitute the restriction to protection scope of the present invention, are the diagram as the preferred embodiment of the present invention.
Description of drawings
Fig. 1 has showed the cross sectional representation of multimode graded-index optical fiber;
Fig. 2 has showed the deposition method synoptic diagram in the deposited tube;
Fig. 3 has showed that the specific refractory power (RI) of multimode optical fibers distributes, and has represented the ideal distribution according to optical fiber of the present invention, the conventional distribution and distribution respectively;
Fig. 4 has showed the layering α of each settled layer according to conventional methods and the desirable layering α of each settled layer;
Fig. 5 has showed the layering α and the desirable layering α of each settled layer according to an embodiment of the invention;
Fig. 6 has showed the time of lag (ps) that time lag (ns) that sandwich layer according to conventional methods directly makes progress and desirable α distribute;
Fig. 7 has showed time of lag (ps) that the time lag of sandwich layer radial direction (ns) and desirable α according to an embodiment of the invention distribute.
Embodiment
The invention discloses a kind of layering specific refractory power of radially discerning, thereby determine layering α, and the separation time of definite optical signal postpones (ns).This layering differential mode delay is used for modified index of refraction and distributes, thereby on the wavelength region 850nm that covers sandwich layer center and outer peripheral areas respectively～1300nm, obtain required α and be about 1.9～2.0, thereby reduce mode dispersion to improve bandwidth, make at wavelength respectively in 850nm and 1300nm bandwidth on 200/500MHzKm preferred 500/800MHzKm.
Among Fig. 1, the diameter of the sandwich layer 3 of multimode optical fibers is 40～70 μ m, and is about covering 1 parcel of 125 μ m by diameter, and the respective indices of refraction of sandwich layer and covering is represented by n1 and n2 respectively.The refractive index n 1 of sandwich layer is a parabolic shape, is called as gradation type and distributes.The curve 3a of the sandwich layer of being represented by α 3 needs to correct, to improve the bandwidth of an optical fiber performance.
According to one embodiment of present invention, multimode optical fiber preform can be by existing any means manufacturing, such as chemical Vapor deposition process, as shown in Figure 2.Chemical reactant enters deposited tube 4 from inlet end 7, and deposited tube 4 is by thermal source 5 heating, thus the chemical reaction in the pipe, along with the rotation formation soot particle of pipe 4.Reacted cigarette ash 6 is removed from the heating region streamwise, and falls in the pipe to form deposition as shown in Figure 2.The reaction that occurs in the pipe can be represented by following equation (3):
SiCl
4+O
2----->SiO
2+2Cl
2 (3)
Above SiO
2Deposition occur in subsequently layer, to cover settled layer.Tectum 2 is arranged between pipe and the sandwich layer, diffuses into sandwich layer to minimize OH.After required tectum 2 is finished, sandwich layer deposition beginning and successive sedimentation, every layer of cross-sectional space reduces the center until sandwich layer 3.
For the refractive index n 1 that increases sandwich layer 3, the chemical substance of mixing below preferred: germanium tetrachloride GeCl
4, phosphorus oxychloride PoCl
3, fluorine Lyons Freon; Thereby these chemical substances are can the different exponential distribution that obtain shown in Fig. 1 (3a) in every layer.Silicon tetrachloride SiCl
4Flow and germanium tetrachloride GeCl
4Flow also can be different in each layer, to obtain distribution shape 9 as shown in Figure 3.
Hotchpotch halogenide changes according to layering α in each sandwich layer settled layer, thereby forms the exponential distribution of radial variations.Doping halogenide, Phosphorates phosphorus Halides change according to silicon halide flow or doping halogenide fluctuations in discharge in the sandwich layer settled layer.
After the required layer thickness of sandwich layer formed, halid supply can be stopped, and decomposition course begins to decompose pipe to form prefabricated rods.In decomposition course, fluorine Lyons gas is preferably at 10 to 50sccm (standard ml/min) flow, thereby this fluorine Lyons gas reduces central dip through pipe with the corrosion core layer surface.
Based on correction factor, the made prefabricated rods of this mode adopts method of the present invention to correct index distribution, difference between described correction factor is postponed by desirable layering mould delay and actual layering mould is determined, by radially determining the specific refractory power of sandwich layer, draw the peak value of index distribution and valley to determine the layering index distribution of each settled layer, thereby drawn every layer of layering α that the footpath makes progress, the hierarchical delay that makes progress with the footpath of calculating each settled layer.The variation of the index distribution guiding reaction parameter of revising.In one embodiment, the invention provides a kind of manufacture method of multimode optical fibers of high bandwidth, comprise by aforesaid mode or existing method and prepare preform, make prefabricated rods make the diameter according to the sandwich layer specific refractory power of utilizing the prefabricated rods analyser to measure, sandwich layer, the α value of sandwich layer, the specific refractory power of covering and the diameter preparation of covering, to determine the profile of prefabricated rods, it is characterized in that:
A), determine the index distribution of sandwich layer at each settled layer according to sandwich layer prefabricated rods profile;
B) according to the index distribution of the sandwich layer of step a gained, at the peak value and the valley of radially determining index distribution of prefabricated rods;
C) according to the peak value of step b gained and the center line average of valley, determine every layer index distribution;
D) according to the specific refractory power of each settled layer of step c gained, radially determining layering α;
E) α that obtains according to steps d calculates hierarchical delay;
F) postpone to determine correction factor according to desirable layering mould delay and actual layering mould, to obtain every layer of required α index distribution;
G) based on correction factor, obtain required α index distribution by changing reaction parameter, these parameters such as doping agent flow or concentration or temperature of reaction or the like, thus form prefabricated rods to form the optical fiber of high bandwidth.
By equation (1), according to the index distribution of each settled layer, determining step d) layering α:
n(r)＝n
1(1-2Δ(r/a)
α)
1/2 (1)
Wherein, n
1The specific refractory power at expression sandwich layer center; n
2The specific refractory power of expression covering, α represents the sandwich layer shape index, Δ is represented refractive index contrast, shown in equation (2):
Δ＝(n
1-n
2)/n
1 (2)
Utilize mould to postpone equation 4, the hierarchical delay in the step e) is calculated by the α of gained in the step d):
D＝1+(α-2)/(α+2).Δ.F+(3α-2)/(α+2).(Δ.f)
2/2 (4)
Wherein, D is a propagation delay
F＝(m/M)
g＝(r/a)
2g
G＝(α/α+2)
α is the alpha parameter of sandwich layer specific refractory power
Δ is the refringence between equation (2) center core layer and the covering.
The correction factor of step f) is determined by utilizing following experience equation (5):
Correction factor=1+K (target delay-actual delay)/target delay (5)
Wherein k is the constant in 0.5～1 scope
Target delay is to calculate by above-mentioned equation (4), and target α and actual delay calculate by the actual α that utilizes above-mentioned equation (4) and each settled layer.From equation (5),, can obtain every layer correction factor according to every layer actual delay.Utilize the correction factor of following form to change reaction parameter:
Old reaction parameter in new reaction parameter=correction factor in every layer * every layer
In another embodiment, the invention provides a kind of manufacture method of multimode optical fibers of high bandwidth, comprise that above-described mode or existing method prepare preform, sandwich layer specific refractory power, sandwich layer diameter, sandwich layer α value, cladding index and cladding diameter that prefabricated rods is measured according to the prefabricated rods analyser are made, to determine the prefabricated rods profile, it is characterized in that:
A. according to the prefabricated rods profile of sandwich layer, the sandwich layer index distribution of determining at each settled layer;
B. the index distribution of the sandwich layer that obtains according to step a is along the peak value and the valley of radially determining index distribution of prefabricated rods;
C. according to the peak value of step b acquisition and the center line average of valley, determine every layer index distribution;
D. the specific refractory power of each settled layer that obtains according to step c is determined layering α;
E. determine correction factor from the difference between desirable layering α and the actual layering α, to obtain every layer required layering α specific refractory power;
F. based on correction factor, required layering α specific refractory power obtains by changing reaction parameter, such as doping agent flow or concentration or
Person's reaction times or the like, thus prefabricated rods, the light that has high bandwidth with formation formed.
Utilize equation (1), according to the index distribution of each settled layer, the layering α of determining step d radially:
n(r)＝n
1(1-2Δ(r/a)
α)
1/2 (1)
N wherein
1Represent the specific refractory power at sandwich layer center;
n
2Represent the specific refractory power of covering, α represents the sandwich layer shape index;
Δ is represented the relative refractive index of following equation (2):
Δ＝(n
1-n
2)/n
1 (2)
The correction factor of experience equation (6) determining step e below utilizing:
Correction factor=1+K (target α-actual α)/target α (6)
Wherein k is the constant in 0.5～1.
Actual α calculates by equation (1), and the scope of target α is 1.9～2.By equation (6), determine the correction factor of each settled layer according to actual α, reaction parameter changes by following mode:
Every layer of new reaction parameter=correction factor * every layer of old reaction parameter
Refractive index profile shape 9 is according to conventional methods seen shown in Figure 3.The index distribution that obtains from the distributional analysis instrument has provided the whole α values based on the optimal curve of actual deposition index distribution.Even the whole α values that reached equal ideal value, the change in the manufacturing processed causes specific refractory power local variation radially.Therefore, determining the definite position of these variations in the radial direction, reduce the local variation that specific refractory power directly makes progress then, thereby improve the bandwidth of multimode optical fibers, be very challenging, and method of the present invention has successfully reached these purposes.
The analyser of prefabricated rods provides all α values of the optional position on the plug length direction usually, and profile view is considered the global shape of sandwich layer profile, and 15%～95% the optimal curve that distributes based on the every side actual refractive index shown in the dotted line of prior art Fig. 3.
The plug of manufacturing is loaded on the chuck of prefabricated rods analyser, with refractive Index Distribution Measurement.This prefabricated rods analyser mainly comprises the case that refractive index match liquid is housed, and plug inserts in the described liquid, and having optical maser wavelength is the light unit of 632.8nm, and detector.After measuring beginning, laser beam scans the radially whole of plug.Because the variations in refractive index of plug, light departs from, and by the detector measurement deviation angle.The unit of deviation angle represents with radian.The reconstruction algorithm of 5 microns step-lengths is got in utilization, and the data that will depart from are rebuild into index distribution.Specific refractory power can be by utilizing the profile analysis instrument, and for example the PK2600 of PK technology instrument records about 0.0002.
The profile analysis instrument is with the specific refractory power of the interval measurement sandwich layer in 5 microns of plug stages, and this is equivalent to 0.02 micron of optical fiber stage.For example, in order to make 50 microns multimode optical fiberss, the sandwich layer diameter of plug should be near 13 millimeters, i.e. 13000 micron diameters, thus equal about 0.02 micron of optical fiber stage.
From the prefabricated rods outline data, the technology of the present invention is to determine the index distribution of each stratified sedimentation layer.These index distribution data will be used for determining the footpath upwards peak value and the valley of specific refractory power.In the chemical Vapor deposition process (MCVD) of improvement, the specific refractory power of sandwich layer is rough diametrically, and ripple is arranged.The corresponding settled layer of each described ripple, and can characterize by peak value and valley.Therefore, a crest and a trough are represented a settled layer, and the center line average of a crest and a trough is the specific refractory power of a layer.
Similarly, the specific refractory power of all layers can calculate by present method, and when radially arriving the difference of successive crest or trough, present method also can provide the thickness information of layer.Adopt above-mentioned layering refractive index information, and utilize above-mentioned equation (1) to calculate layering α.By the layering refractometry to layering α as shown in Figure 4, its dotted line 12 is represented each settled layer, and desirable α radially is by Fig. 4 center line 11 expression.From layering α data, utilize the intermode time-delay equation among " the Introduction to optical fiber communication systems " that prior art WilliamB.Jones delivers to calculate hierarchical delay, this equation is improved to produce hierarchical delay as shown in Figure 5 by the present invention:
D＝1+(α-2)/(α+2).Δ.F+(3α-2)/(α+2).(Δ.f)
2/2 (4)
Wherein D is a propagation delay
F＝(m/M)
g＝(r/a)
2g
G＝(α/α+2)
α is the alpha parameter of sandwich layer specific refractory power
Δ is the refractive index difference between sandwich layer and the covering, shown in equation (2).
Time lag Figure 16 has shown the time lag that the optical fiber made according to conventional methods directly makes progress and calculated.Among this time lag figure, each settled layer of some expression.Similarly, utilize every layer the desirable α of target,, calculate ideal delay Figure 17 of every layer such as 1.96.Departing between actual delay Figure 15 and ideal delay Figure 21 shown that deposition process is towards the localized variation that has taken place.
In the one embodiment of the invention, correction factor is rule of thumb obtained by the difference that actual mould postpones and ideal mode postpones, correction factor is used to obtain optimum α index distribution by changing every layer of chemicals, for example change doping agent flow or concentration or temperature of reaction, thereby obtain almost identical actual delay figure, with the maximization bandwidth of an optical fiber with ideal delay figure.
In the another embodiment of the present invention, correction factor also can according to the difference experience of desirable layering α and actual layering α obtain, correction factor is used for obtaining optimum α layering index distribution by the chemicals that change is deposited in the pipe, for example flow or concentration or temperature of reaction, thereby the optimum α in reaching every layer is with the bandwidth of maximization multimode optical fibers.
The layering specific refractory power of sandwich layer is used to obtain layering α value and separation time delay figure, and index distribution is changed with the minimizing intermode dispersion, thus the bandwidth of maximization multimode optical fibers.After revising the chemicals flow, make prefabricated rods subsequently, and measure layering index distribution and time lag once more, to correct index distribution.The plug of manufacturing is loaded in the prefabricated rods analyser according to the present invention, with refractive Index Distribution Measurement.Index distribution 10 as shown in Figure 3 is an index distribution of the present invention.According to analyser, utilize the optimal curve of index distribution 9 and 10, the α observed value is respectively 1.95 and 1.96, these two numerical value can be considered equal, but compare with the sandwich layer fringe region of index distribution 9, layering α 12 departs from the target α 11 of central zone, and this will cause the signal delay of the central zone of sandwich layer.According to the present invention,, reduced departing from of layering α 14 relative target α 13 by utilizing the technology of discerning the layering index distribution, determining layering α and definite hierarchical delay figure.
The layering α that is recorded by the layering specific refractory power sees shown in Figure 5, its dotted line 14 each settled layers of expression, and α radially is shown in the line 13 of Fig. 5.Among Fig. 5, layering α dotted line 14 according to the present invention is modified to optimum α 13 no better than.From layering α data, utilize equation (4) as above to calculate hierarchical delay.The hierarchical delay figure that obtains according to the present invention represents with the dotted line among Fig. 7 18, and the 17 expression ideal delay times of line.In conjunction with technology of the present invention, hierarchical delay and layering α can reach target α and target hierarchical delay no better than by continuously.Utilize this method, index distribution can be optimised, to reach the maximum bandwidth of multimode optical fibers.
According to the present invention, prepared multimode optical fiber preform further is drawn as the size of required optical fiber.Prepared multimode optical fibers has quite high bandwidth according to the present invention, and for example wavelength is 850 and during 1300nm, bandwidth respectively from 120 and 225MHzKm increase to 490 and 350MHzKm, preferably to about 1050 and about 1200MHzKm.
Multimode optical fibers constructed in accordance has largest refractive index along described fiber axis, and the specific refractory power of its fringe region is lower.
Following example will make invention clearer, and these examples are not intended to limit the scope of the invention.
More than described the present invention and can be used to make multimode optical fibers, but the present invention also can be used to make single-mode fiber, to improve the profile characteristic, this is also contained in the scope of the present invention.Therefore, the present invention relates to have in the sandwich layer optical fiber manufacturing method of largest refractive index.
Example 1:
Deposit prefabricated rods according to conventional methods, reaching between the described target α value 1.9～2 of prior art, and corresponding index distribution is measured by the profile analysis instrument.The α value of this sandwich layer is 1.96, and this is very near target value, but the bandwidth that has from the stretched sandwich layer of plug is very low, 850 and the 1300nm wavelength under be respectively 123 and 225MHzKm.
Example 2:
The method according to this invention is analyzed above-mentioned profile, to determine the low reason of bandwidth under the target α.The dotted line of hierarchical delay Figure 16 of above-mentioned plug and ideal delay Figure 15 have very big fluctuation, as shown in Figure 6.Based on departing from of this and ideal delay, the experience equation of utilization calculates every layer correction factor.This correction factor is used to change every layer doping agent flow, and deposits second plug.Measure the specific refractory power of this plug, obtaining the α value is 1.955.This profile is according to being used for before checking that whether the inventive method of localized variation was carried out layer analysis.Among time lag Figure 18, dotted line radially closely reduces, as shown in Figure 7.Time lag Figure 18 of second plug compares with time lag Figure 16 of example 1, and obviously the difference of ideal delay figure and actual delay figure reduces, but still has some fluctuations.After second prefabricated rods was stretched, the fiber bandwidth that obtains is was respectively 491MHzKm and 352MHzKm under wavelength 850nm and 1300nm.
Example 3:
Based on the correction factor that second plug obtains, further correct layering doping agent flow, make another root plug.The α value of this plug is 1.96, obtains hierarchical delay figure according to this example.This postpones figure very near ideal diagram, except the center and peripheral because of concavity.After this plug was stretched, its bandwidth was respectively 750MHzKm and 880MHzKm at wavelength 850nm and 1300nm.
Example 4:
Make described the 3rd plug by the method for above example 3, afterwards, utilize the profile analysis instrument to analyze its index distribution according to the inventive method.The method according to this invention is utilized following equation, based on layering α and target α, determines the layering specific refractory power of each settled layer:
Correction factor=1+K (target α-actual α)/target α
Equation based on correction factor below every layer doping halogenide flow utilizes improves:
The old doping agent flow that every layer new doping agent flow=correction factor X is every layer
Based on the above new doping halogenide flow that calculates, make the 4th plug, after prefabricated rods was drawn as optical fiber, its bandwidth was respectively 950MHzKm and 1100MHzKm under wavelength 850nm and 1300nm.
Example 5:
Adopt as described in Example 3 method to make the 5th plug, after this, utilize the profile analysis instrument to analyze the index distribution of the 5th plug according to the inventive method.The method according to this invention is utilized following equation, postpones to determine every layer correction factor based on separation time delay and object time:
Correction factor=1+K (target delay-actual delay)/target delay
Utilize following equation, improve every layer the halid concentration of doping based on correction factor:
Old doping halogenide flow in new doping halogenide flow=correction factor in every layer * every layer
Make the 5th plug based on the above new doping halogenide flow that calculates, its bandwidth bandwidth under wavelength 850nm and 1300nm is respectively 1050MHzKm and 1200MHzKm.
The present invention has done corresponding description in conjunction with the accompanying drawings.Obviously, for those skilled in the art, the modification that the inventive method is not departed from invention scope will be included in the scope of the present invention.
Claims (17)
1. manufacture method with multimode optical fibers of high bandwidth, comprise the making of preform, prefabricated rods is made according to sandwich layer specific refractory power, sandwich layer diameter, sandwich layer α value, cladding index and the cladding diameter of utilizing the prefabricated rods analyser to measure, to determine the profile of prefabricated rods, it is characterized in that:
A. according to the prefabricated rods profile of sandwich layer, in the index distribution of definite sandwich layer of each settled layer;
B. according to the index distribution of step a acquisition, radially determine the peak value and the valley of index distribution along prefabricated rods;
C. according to the peak value of step b acquisition and the center line average of valley, determine every layer index distribution;
D. the specific refractory power of each settled layer that obtains according to step c is measured layering α diametrically;
E. the layering α that obtains according to steps d calculates hierarchical delay:
F. determine correction factor according to the difference that desirable layering mould postpones and actual layering mould postpones, to obtain every layer of required index distribution;
G. based on correction factor,,, obtain required α index distribution, thereby form prefabricated rods to form the optical fiber of high bandwidth such as doping agent flow or concentration or temperature of reaction or the like by changing reaction parameter.
2. method according to claim 1 is characterized in that, by the index distribution of each settled layer, utilizes equation (1) to determine layering α in the described steps d diametrically:
n(r)＝n
1(1-2Δ(r/a)
α)
1/2 (1)
N wherein
1The refractive index of the centre of expression sandwich layer; n
2The specific refractory power of expression covering, α represents the sandwich layer shape index, Δ is expressed as follows the refractive index contrast shown in the equation 2:
Δ＝(n
1-n
2)/n
1 (2)
3. method according to claim 1 and 2 is characterized in that, utilizes mould to postpone equation 4, and the layering α that is obtained by steps d calculates the hierarchical delay among the described step e:
D＝1+(α-2)/(α+2).Δ.F+(3α-2)/(α+2).(Δ.f)
2/2 (4)
Wherein D is a propagation delay
F＝(m/M)
g＝(r/a)
2g
G＝(α/α+2)
The alpha parameter of α sandwich layer specific refractory power
Δ is sandwich layer shown in the equation (2) and the refractive index difference between the covering.
4. according to any described method of claim of claim 1-3, it is characterized in that correction factor described in the described step f is determined by following experience equation (5):
Correction factor=1+K (target delay-actual delay)/target delay (5)
5. method according to claim 4 is characterized in that, described target delay calculates by described equation (4), and target α and actual delay calculate by the actual α of equation (4) and each settled layer.
6. according to aforementioned any described method of claim, it is characterized in that described reaction parameter is utilized correction factor, change in the following manner:
The old reaction parameter of new reaction parameter=correction factor of every layer * every layer
7. manufacture method with multimode optical fibers of high bandwidth, comprise the making of preform, prefabricated rods is made according to the sandwich layer specific refractory power of utilizing the prefabricated rods analyser to measure, sandwich layer diameter, sandwich layer α value, cladding index and cladding diameter makes, to determine the profile of prefabricated rods, it is characterized in that:
A. according to the prefabricated rods profile of sandwich layer, determine the index distribution of sandwich layer at each settled layer;
B. according to the index distribution of step a acquisition, radially determine the peak value and the valley of index distribution along prefabricated rods;
C. according to the peak value of step b acquisition and the center line average of valley, determine every layer index distribution;
D. the specific refractory power of each settled layer that obtains according to step c is determined layering α diametrically;
E. determine correction factor according to the difference that desirable layering mould postpones and actual layering mould postpones, to obtain every layer of required index distribution;
F. based on correction factor,,, obtain required α index distribution, thereby form prefabricated rods to form the optical fiber of high bandwidth such as doping agent flow or concentration or temperature of reaction or the like by changing reaction parameter.
8. method according to claim 4 is characterized in that, by utilizing equation (1), the α from the radially definite described steps d of the index distribution of each settled layer:
n(r)＝n
1(1-2Δ(r/a)
α)
1/2 (1)
Wherein, n
1The specific refractory power at expression sandwich layer center; n
2The specific refractory power of expression covering, α represents the sandwich layer shape index, Δ is represented the refractive index contrast shown in the equation 2:
Δ＝(n
1-n
2)/n
1 (2)
9. according to claim 7 or 8 described methods, it is characterized in that, utilize following experience equation (6) to determine described correction factor among the described step e:
Correction factor=1+K (target α-actual α)/target α (6)
Wherein K is 0.5～1 constant.
10. method according to claim 9, wherein said actual α calculates by described equation (1), and the scope of target α is 1.9～2.
11., it is characterized in that described reaction parameter is by utilizing correction factor according to any described method of claim of claim 7 to 10, the mode below adopting changes:
The old reaction parameter of new reaction parameter=correction factor of every layer * every layer
12. according to aforementioned any described method of claim, it is characterized in that described doping agent is a halide gas, preferred germanium halide and Phosphorates phosphorus Halides gas.
13., it is characterized in that based on described correction factor, described halide-doped dose is what change, thereby forms the exponential distribution of radial variations according to aforementioned any described method of claim in described settled layer.
14. the manufacture method of a multimode optical fibers, this multimode optical fibers is as described in conjunction with previous example and shown in the accompanying drawing.
15. the multimode optical fibers with high bandwidth, under its medium wavelength 850 and the 1300nm, its bandwidth from about 120 and 225MHzKm increased respectively to about 490 and 350MHzKm.
16. the multimode optical fibers with high bandwidth, under its medium wavelength 850 and the 1300nm, bandwidth from about 120 and 225MHzKm increased respectively to about 750 and 880MHzKm.
17. a multimode optical fibers has largest refractive index on the axis of wherein said optical fiber, the edge of described optical fiber has lower specific refractory power.
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| US8520994B2 (en) | 2008-09-17 | 2013-08-27 | Ofs Fitel, Llc | Bandwidth-maintaining multimode optical fibers |
| US9481599B2 (en) | 2010-12-21 | 2016-11-01 | Corning Incorporated | Method of making a multimode optical fiber |
| BR112014026771B1 (en) | 2012-04-27 | 2022-03-15 | Fisher & Paykel Healthcare Limited | Humidifier for respiratory humidification system |
| CN105764560B (en) | 2013-09-13 | 2018-04-06 | 费雪派克医疗保健有限公司 | Connection for humidification system |
| WO2015119515A1 (en) | 2014-02-07 | 2015-08-13 | Fisher & Paykel Healthcare Limited | Respiratory humidification system |
| JP6777547B2 (en) | 2014-06-03 | 2020-10-28 | フィッシャー アンド ペイケル ヘルスケア リミテッド | Flow mixer for respiratory therapy system |
| EP4063811A1 (en) | 2016-12-07 | 2022-09-28 | Fisher & Paykel Healthcare Limited | Seal/cover for use with a sensing arrangement of a medical device |
| CN112214864B (en) * | 2020-08-04 | 2024-02-09 | 沈阳工业大学 | Multichannel multilayer laser cladding layer size prediction method |
| WO2023055554A1 (en) * | 2021-09-29 | 2023-04-06 | Corning Incorporated | Multimode optical fiber core cane classification method |
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| US4292341A (en) * | 1980-02-26 | 1981-09-29 | Bell Telephone Laboratories, Incorporated | Method of controlling the index profile of optical fiber preforms |
| US4286979A (en) * | 1980-06-23 | 1981-09-01 | Bell Telephone Laboratories, Incorporated | Fabrication of optical fibers using differential mode-group delay measurement |
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| CN106772789A (en) * | 2017-03-25 | 2017-05-31 | 聊城大学 | A kind of low nonlinearity coefficient less fundamental mode optical fibre |
| CN106772789B (en) * | 2017-03-25 | 2019-06-07 | 聊城大学 | A kind of low nonlinearity coefficient less fundamental mode optical fibre |
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