CN1198157C - Improved multimode optical fiber and its prepn. method - Google Patents
Improved multimode optical fiber and its prepn. method Download PDFInfo
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- CN1198157C CN1198157C CN 02139181 CN02139181A CN1198157C CN 1198157 C CN1198157 C CN 1198157C CN 02139181 CN02139181 CN 02139181 CN 02139181 A CN02139181 A CN 02139181A CN 1198157 C CN1198157 C CN 1198157C
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Abstract
The present invention relates to a multimode optical fiber and a manufacturing method. The diameters of a sandwich layer and a coated layer of the multimode optical fiber is respectively 50 and 125 mum, the refractive index distribution is accurately optimized at the wavelength of 850 nm, the delaying test curve of the optical-fiber differential mode is the curve which continuously rises or descends, and the maximum change is smaller than 0.33 ps/m; when the full-implantation bandwidth is at 850 nm, a value is more than 1500MHz. km; when at 1300 nm, the value is more than 600 MHz. km; when the effective bandwidth is at the 850 nm and the 1300 nm, the value is respectively more than 2000 MHz. km/600MHz. km. In the manufacturing method, a deposition speed is from 2.5 g/min to 1.5 g/min, the germanium steam flow is from 3% to 60%, the diameter of a melting-shrinking hole during the melting-shrinking process is controlled between 2 and 8mm, and C#-[2]F#-[6] etching gas is led into so that the inner tube wall erosion is carried out; the optical fiber is kneaded in the thread drawing process. The present invention completely eliminates the central dent of the multimode optical fiber, reduces the inter-mode delay, and increases the bandwidth of the optical fiber; the present invention not only can be used for a high-speed network system, but also can be used for a low-speed network system.
Description
Technical field
The present invention relates to a kind of optical fiber and manufacture method thereof, particularly relate to a kind of multimode optical fiber and manufacture method thereof.
Background technology
Multimode optical fiber is a kind of data communication optical fiber that early uses in communication system.Multimode optical fiber is because it has bigger core diameter and numerical aperture, and a plurality of stable conduction modes (usually hundreds of with more than) are arranged, and big light transmission energy and comparatively loose technical requirement are used in optical communication field always.But multimode optical fiber has influenced the application of multimode optical fiber in express network because the existence of a plurality of transmission modes makes CHROMATIC DISPERSION IN FIBER OPTICS very big.As everyone knows, CHROMATIC DISPERSION IN FIBER OPTICS mainly comprises material dispersion, waveguide dispersion and modal dispersion (also claiming intermode dispersion).For single-mode fiber, owing to have only single mode transfer, therefore there is not modal dispersion, and the numerical value of material dispersion and waveguide dispersion is opposite in certain wavelength coverage, therefore can make that the chromatic dispersion of optical fiber on a certain wavelength is zero by waveguide design, in this sense, the message transmission rate of single-mode fiber does not have the upper limit.But for multimode optical fiber, because the existence of a plurality of patterns, its intermode dispersion will cause the broadening of light pulse, greatly limit the bandwidth characteristic of multimode optical fiber.
The bandwidth of multimode optical fiber generally uses MHzkm to be unit, its meaning is under certain fiber lengths, change the modulating frequency of going into fine light pulse, the maximum modulating frequency when power attenuation reaches 3dB and the product of fiber lengths, the bandwidth that records when completely injecting when incident light pulse is for completely injecting bandwidth, when incident light pulse exceed mould when injecting measured bandwidth be called and limit the mould bandwidth.Bandwidth is the sign of the optical characteristics of multimode optical fiber at frequency domain, and its sign in time domain is generally used DMD, it is the differential mode delay of multimode optical fiber, the method of testing of the differential mode delay of multimode optical fiber is: use the single-mode optics pulse incident of small light spot at end face of multimode optical fiber to be measured, and in the delay and the division situation of the other end test light pulse of optical fiber.By the incoming position of change light pulse, difference pulse delay time of receiving end, this mistiming is exactly so-called multimode optical fiber differential mode delay.The optical characteristics of multimode optical fiber can utilized bandwidth and DMD sign.Bandwidth is completely injected in the general use of multimode optical fiber for standard, multimode optical fiber for 62.5/125 micron, the full injection bandwidth of its 850nm and 1300nm is generally 160MHzkm/500MHzkm, and the full injection bandwidth of 50/125 micron multimode optical fiber is generally 500MHzkm/500MHzkm.Because their expection environment for use is generally the slow network of using led light source, so do not have the index request of finite module bandwidth and DMD.
The stage of step-refraction index multimode optical fiber and graded index multimode optical fiber has been experienced in the development of multimode optical fiber.Can prove that gradient index fibre has the bandwidth of better dispersion characteristics and Geng Gao.Current, general graded index multimode optical fiber is a silica-based optical fibers, i.e. the sandwich layer of optical fiber and be glass material around the covering of sandwich layer, and the outside is again coated with the glass surface of resin with protection optical fiber.The index distribution of its center core layer is:
n(r)＝n
1[1-2Δ(r/a)
g]
1/2
Wherein:
In the following formula, n
1Be fiber optic hub refractive index, n
2Be the fibre cladding refractive index, a is the sandwich layer radius of optical fiber, and Δ is the refractive index contrast of core centre and covering.
For general graded index multimode optical fiber, its profile exponent g approximately is 2, a promptly similar second-degree parabola structure.Theoretical analysis shows that for the multimode optical fiber with above-mentioned class parabolic refractive index structure, in ideal conditions, the light of different mode arrives simultaneously by different transmission paths, can eliminate the influence of intermode dispersion, and the bandwidth of multimode optical fiber is increased.But in the optical fiber manufacture process of reality, because the existence of various factors, the sandwich layer index distribution of multimode optical fiber is difficult to reach above-mentioned requirements.Cause the reason of this situation, in the existing optical fiber production process, system aspects is arranged also.Generally speaking, following factors are arranged:
1, for the production of multimode optical fiber, owing to need accurate sandwich layer refractive index control, method has advantage in the pipe, comprises modified chemical vapor deposition process (MCVD) (MCVD) and plasma chemical vapor deposition (PCVD).The interior method of pipe is because the lower rate of sedimentation and the more deposition number of plies make refractive index control comparatively accurate and easy.But method also has its defective that is difficult to overcome in the pipe, as central concave.The phenomenon that central concave promptly descends in the centre of optical fiber refractive index.This central concave is owing to finish the post-depositional compression process that melts and cause because of the volatilization of center dopant material.The optical fiber of method preparation exists the central concave phenomenon to know in the industry in the pipe.The existence meeting of this central concave influences the bandwidth of an optical fiber characteristic greatly.Make the light path of core reduce because the fiber optic hub refractive index descends, can cause the broadening and the division of light pulse, reduce the amount of bandwidth of multimode optical fiber.
2, the multimode optical fiber of standard, as A1a, the A1b multimode optical fiber, its expection environment for use is to use the slow network of led light source, as 10Mbit/s, the Ethernet of 100Mbit/s and other network systems.In this network system, in order to be added to fiber optical power, employed is the led light source of full injection.This light source will excite all fiber optic conduction patterns, under this situation, middle model has carried most transmission luminous energies, it is the transport property that middle model has determined multimode optical fiber, and the entrained energy proportion of corresponding low step mode and higher order mode is too small, and is little to the properties influence of fiber bandwidth.Therefore in the manufacture process of optical fiber, the requirement to fiber core layer core and sandwich layer-clad section has accordingly also reduced.
3, multimode optical fiber generally is used in the network system of low speed, in these network systems, generally uses LED as light source.Led light source has bigger spectral width.As everyone knows, the acting in conjunction of chromatic dispersion and spectral width causes pulse strenching, reduces the bandwidth of system.When using led light source, for the graded index multimode optical fiber, also be a principal element by the influence that chromatic dispersion caused.And in the express network system, as 1Gbit/s, 2.5Gbit/s, or 10Gbit/s Ethernet system, use be the LD LASER Light Source, LASER Light Source has narrow spectral width, in this case, because of the modal dispersion that mode delay caused will become principal element, therefore expection is used in the multimode optical fiber of the above network system of 1Gbit/s, must reduce the size of its mode delay, to improve the bandwidth of an optical fiber characteristic.
Reducing decay and improving bandwidth and reduce chromatic dispersion is two main paties that promote the optical fiber technology development.In order to improve the bandwidth of multimode optical fiber, be improved to the multimode graded-index fiber by multimode stepped-index optical fiber except aforesaid, many methods are used.These all methods are basically all based on the theory of mode switch.Promptly for the different conduction modes of multimode optical fiber, for the delay between the minimizing pattern, can enhancement mode or model group between energy conversion, i.e. the coupling of enhancement mode.This frequent energy conversion helps setting up stable mode profile as early as possible, and the pattern with different transmissibility factor is mixed mutually, thereby reduces intermodel delay, improves the bandwidth characteristic of multimode optical fiber.A main method of enhancement mode coupling is to introduce unevenness in waveguide.U.S. Pat 4049413 has been announced a kind of technology of making multimode optical fiber, and this technology etches groove to introduce the geometry unevenness of fiber core radius on preform.U.S. Pat 3982916 proposes the sandwich layer of the deposition different refractivity of stagger cycle property when prefabricated fiber rod depositing to introduce optical heterogeneity.U.S. Pat 3980459 proposes the manufacture method of eccentric multimode optical fiber.United States Patent (USP) UA0019652A1 proposes to make the method for oval fuse multimode optical fiber.These all methods can increase bandwidth of an optical fiber really by the method for introducing defective on geometry or optical texture, but also increased the attenuation characteristic of optical fiber simultaneously, and these special-shaped optical fibres are difficult to and existing standard fiber compatibility, have limited their use.
At the central concave and the core-packet boundary defect problem of multimode optical fiber, U.S. Pat 6292612B1 has proposed near a kind of method that increases a ridged and increase a step at core-packet boundary when prefabricated fiber rod depositing the center.The essence of this method is to offset by the increase of these ridgeds and step the optical path difference of corresponding modes or model group, reduces intermodel delay, increases bandwidth of an optical fiber.This method has certain effect to standard multimode fiber, but it does not eliminate central concave, when this multimode optical fiber is used in the network of LD LASER Light Source, because of the pulse that mode delay causes is divided inevitable.
At the highspeed network applications of using LASER Light Source, patent PCT/US00/04366 has proposed the multimode optical fiber of fiber core layer complex refractive index and has made the method for this multimode optical fiber.The multimode optical fiber that this method proposed is: fiber core layer is divided into two zones, be first area and second area, different refractive index distribution curves is used in two zones, as in the first area, use index g1 at the 850nm Wavelength optimization, at the 1300nm Wavelength optimization, use index g2 at second area.Therefore the first area is suitable for using the LASER Light Source of 850nm wavelength, and second area is applicable to the led light source that uses the 1300nm wavelength.In theory, this complex refractive index optical fiber both can be used for slow network, also can be used for express network.But the shortcoming of this design is tangible, because there are two kinds of index distribution in the sandwich layer at multimode optical fiber, when DMD tests, the pulse of diverse location will be divided into two groups, and can produce the bigger relative delay between two groups, in fact reduced the optical property of optical fiber.Especially for the ethernet standard of 10Gbit/s, require the distribute power of light source must meet the EIA/TIA-455-203 standard, the radius of this standard code laser facula must be more than 19 microns, so pulse is coupled into above-mentioned multimode optical fiber and must causes bigger mode delay, makes pulse expansion and reduces optical fiber properties.
Summary of the invention
Technical matters to be solved by this invention is: have central concave and postpone than large model at existing multimode optical fiber, thereby influence the bandwidth of an optical fiber characteristic, reduce optical fiber property, cause influencing the problem of the application of multimode optical fiber in express network, a kind of improved multimode optical fiber and manufacture method thereof are proposed, to remedy the deficiency of existing product.
Technical scheme of the present invention is achieved in that it comprises sandwich layer and covering, it is characterized in that: the sandwich layer of this multimode optical fiber and the diameter of covering are respectively 50 μ m and 125 μ m, its index distribution by accurate optimization at the 850nm wavelength, the differential mode delay test curve of optical fiber is the curve that rises or descend continuously, and its maximum variation less than 0.22ps/m, completely inject bandwidth at 850nm greater than 1500MHzkm, at 1300nm greater than 600MHzkm, effective bandwidth at 850nm and 1300nm respectively greater than 2000MHzkm and 600MHzkm.
Manufacture method of the present invention may further comprise the steps:
(1) adopt that method deposits the sandwich layer doped glass then at deposited tube inside deposition cladding glass in the pipe, sedimentation velocity from 2.5g/min to 1.5g/min, germanium steam flow from 3% to 60%, the deposition number of plies is 4000 layers, core is 200～500 layers and supports by the arm fluorine, boron;
(2) melt after deposition is finished and contract, melt to control when contracting and melt the shrinkage cavity footpath between 2～8mm diameter, melting the time of contracting is 3-8 hour, feeds C then
2F
6Etchant gas carries out the inner tubal wall corrosion, and the concentration of etchant gas is 20～50%, and etching time was controlled at 20-40 minute, burnt till solid preform at last;
(3) drawing process in addition rotation period be the periodicity rubbing of 20～80 commentaries on classics/rice fiber lengths, be drawn into fiber products.
In the above-mentioned manufacture method, the preferred PCVD method of method in the described pipe; Melt preferred 8 hours of the time of contracting; C
2F
6The concentration of etchant gas preferred 40%; Preferred 30 minutes of etching time.
Manufacture method of the present invention adopts the PCVD method, and the deposition process of PCVD method by several thousand layers can accurately be controlled index distribution and finish the manufacturing of the optical fiber with complex index of refraction distribution.The difficulty of this a part of refractive index control is some micromolecule dopant material, as the volatilization and the diffusion of fluorine, boron, can optimize this regional index distribution by the method that increases the doping concentration of small molecule material in the specific region.In this test that is distributed in DMD, show as under a certain wavelength, its relative mode delay curve is the dull curve that rises or descend continuously, so corresponding site injects light pulse and can not divide in transmission course.This advantage makes this optimization multimode optical fiber can use the LASER Light Source of small light spot in express network, small light spot laser is owing to concentrate on low-order mode at injecting power, optimize multimode optical fiber for general laser, be easy to because the cause of central concave causes the pulse division, therefore necessarily require the distribute power of LASER Light Source to meet some requirements, just can be used in the express network transmission.And multimode optical fiber of the present invention is because eliminated central concave fully, and the refractive index of core is by accurate optimization, the phenomenon of the division or the undue expansion of pulse can not occur, therefore say, this multimode optical fiber does not have specific (special) requirements to the emergent power distribution of light source.
In optical fiber, introduce certain unevenness, can improve the bandwidth characteristic of multimode optical fiber.But the method that changes geometry or optical texture in the prior art is worthless.Multimode optical fiber of the present invention is in order to improve the bandwidth of an optical fiber performance, improve the delay division situation of transmission light pulse, in drawing process, by method with respect to the continuous left-right rotation optical fiber of prefabricated rods, introduce the unevenness of structure, the advantage of the method that this unevenness is introduced is: need not to change the structure composition of optical fiber, do not have tangible additional attenuation influence, the optical fiber that is drawn shows more outstanding DMD characteristic.
The present invention has eliminated the central concave of multimode optical fiber fully, reduced intermodel delay, increased bandwidth of an optical fiber, the core refractive index is by accurate Control and Optimization, by in pulling process with respect to prefabricated rods rotate optical fiber with the center split of eliminating pulse to improve the bandwidth of an optical fiber characteristic; Greater than 1500MHzkm and 600MHzkm, DMD is less than 0.22ps/m in the full injection bandwidth of 850nm and 1300nm wavelength for multimode optical fiber of the present invention.This multimode optical fiber in specific wavelength, is made that the requirement to light source when express network uses of this multimode optical fiber is simple relatively by accurate optimization, and this multimode optical fiber not only can be used for the express network system of 10Gbit/s speed rates, also is used for than the slow network system.Use multimode optical fiber of the present invention, can make things convenient for the upgrading of network, reduce the expense and the input of network operation and transformation.Another advantage of multimode optical fiber of the present invention is that the distribute power and the emission mode of LASER Light Source are not had specific (special) requirements, this makes optical fiber of the present invention have advantage in the express network system that uses LASER Light Source, can compatible have the laser instrument that different emergent powers distribute, such as the 850nm VCSEL laser instrument of different manufacturers production.
Description of drawings
Fig. 1 is a structural representation of the present invention.
Fig. 2 fiber drawing tower and optical fiber rubbing device synoptic diagram.
Fig. 3 is the sandwich layer refractive index distribution curve of common multimode optical fiber.
Fig. 4 has the multimode optical fiber of Fig. 3 index distribution in the DMD of 1300nm wavelength test result.
Fig. 5 is the refractive index distribution curve of multimode optical fiber of the present invention.
Fig. 6 has the multimode optical fiber of Fig. 5 index distribution in the DMD of 850nm wavelength test result.
Fig. 7 multimode optical fiber of the present invention is at the change curve of the DMD of 850nm wavelength test result.
Fig. 8 is the DMD test result comparison at same preform institute drawing optical fiber.
Embodiment
Below in conjunction with accompanying drawing the present invention is described further:
As shown in Figure 1, multimode optical fiber 10 of the present invention comprises covering 11 and sandwich layer 12, the sandwich layer of multimode optical fiber and the diameter of covering are respectively 50 μ m and 125 μ m, its index distribution by accurate optimization at the 850nm wavelength, the differential mode delay test curve of optical fiber is the curve that rises or descend continuously, and its maximum variation less than 0.33ps/m, completely inject bandwidth at 850nm greater than 1500MHzkm, at 1300nm greater than 600MHzkm, effective bandwidth at 850nm and 1300nm respectively greater than 2000MHzkm and 600MHzkm.The present invention adopts PCVD deposition cladding glass, deposit the sandwich layer doped glass then, sedimentation velocity is from 2.5g/min to 1.5g/min, germanium steam flow from 3% to 60%, the deposition number of plies is 4000 layers, and core is 200～500 layers and supports by the arm fluorine, boron that the diameter that the center pit that contracts is melted in control is 2mm, melt the time of contracting at 8 hours, the time of contracting of melting of proper extension deposited tube can be improved the geometry homogeneity of prefabricated rods; Use C simultaneously
2F
6Remove in melting compression process because of dopant material as etchant gas, the part that is mainly the volatilization of germanium and refractive index of the centre is descended, accurately the concentration and the etching time of control etchant gas can be eliminated central concave fully, and the concentration of etchant gas can be 40%, and etching time was controlled at 30 minutes.In addition, in preparation process, should put forth effort to optimize the index distribution of fiber optic hub part at optical fiber, index distribution as fiber optic hub 5～15 micrometer ranges, in this zone, index distribution should be by accurate optimization in a certain operation wavelength, as the 850nm wavelength.
Fig. 3 is the refractive index distribution curve of common 50/125 micron multimode optical fiber sandwich layer.Because the standard multimode fiber expection is used in the slow network system of led light source, and is insensitive for low step mode group and higher order mode group, therefore generally has central concave at the center of common multimode optical fiber, shown in circle part among Fig. 3.This central concave is not obvious to the influence of the full injection bandwidth of multimode optical fiber, simultaneously because 50/125 micron multimode optical fiber only is 500MHzkm at the bandwidth requirement of 850nm, therefore the pattern relative delay is bigger, Fig. 4 is this optical fiber ground of 1300nm wavelength measurement DMD result, the relative mould that shows fiber optic hub and sandwich layer marginal portion postpones to be approximately 3ps/m, and the multimode optical fiber of this delay can't be used in the express network transmission.
Fig. 5 is the refractive index distribution curve of 50/125 micron multimode optical fiber optimizing through center and sandwich layer index distribution and the theoretical distribution of requirement.Provided its distribution among the figure with respect to radius.As can be seen, actual index distribution and theoretical desired refractive index distribution curve almost completely overlap, and have eliminated near the saltus step central concave and the core-Bao.The elimination of this central concave and core-Bao saltus step is to rely on accurately control to mix up ratio and the volatilization realization of inhibition center.Fig. 6 be its drawing optical fiber in the DMD of 850nm wavelength test result since this optical fiber by accurate optimization at the 850nm wavelength, relatively the mode delay curve is continuous propradation.This accurate optimization to the 850nm wavelength, the center of this optical fiber only is 0.22ps/m with the relative mode delay of core-bound edge edge part simultaneously, this specific character makes this optical fiber be suitable for the LASER Light Source of 850nm, and the distribute power of laser pulse be need not to do strict requirement, comprise the single-mode laser light source of respective wavelength.The 850nm of this root optical fiber and 1300nm wavelength completely inject bandwidth and reach 2100MHzkm/650MHzkm.
Because the bandwidth characteristic of multimode optical fiber is a kind ofly both to distribute with the refractive index profile of optical fiber, therefore relevant with vertical unevenness of optical fiber again comprehensive effect is introduced certain unevenness and is strengthened its Mode Coupling and have positive meaning to improve the bandwidth of an optical fiber characteristic in optical fiber.In the present invention, we are by making optical fiber do continuous left-handed and right-lateral movement with respect to prefabricated rods in fiber draw process.This rotatablely moving can be added a rotation rubbing device and got final product on fiber drawing tower, as shown in Figure 2.It is simple that the introducing of this rotation unevenness has method, to the geometry and the minimum feature of fade performance influence of optical fiber.Fig. 8 is the comparison of the DMD test result of same standard multimode fiber pulling optical fiber preform, and wherein a part is introduced and rotated, and another part is not introduced rotation.Can find out obviously that from figure because the introducing of rotating, the division of pulse center section disappears, the broadening of pulse simultaneously also reduces to some extent.The introducing that shows this helical rotation is the bandwidth characteristic that helps to improve multimode optical fiber.Geometry and attenuation test to two sections optical fiber simultaneously shows there is not significant difference.
Significantly, multimode optical fiber of the present invention also can adopt the manufacturing of MCVD method, and the multimode optical fiber of this invention simultaneously is applicable to that also all have the multimode optical fiber of analog structure, comprises the multimode optical fiber of communication multimode optical fiber and other specific uses.
In the manufacture process of the present invention, the diameter that melts the center pit that contracts may be controlled to 3mm, 4mm, 5mm, 6mm, 7mm or 8mm; Melting the time of contracting can be 3,4,5,6,7 hours, and the concentration of etchant gas can be 20%, 30% or 50%, and etching time can be controlled at 20 or 30 minutes.
Claims (3)
1, a kind of improved multimode optical fiber, it comprises sandwich layer and covering, it is characterized in that: the sandwich layer of this multimode optical fiber and the diameter of covering are respectively 50 μ m and 125 μ m, its index distribution by accurate optimization at the 850nm wavelength, the differential mode delay test curve of optical fiber is the curve that rises or descend continuously, and its maximum variation less than 0.22ps/m, completely inject bandwidth at 850nm greater than 1500MHzkm, at 1300nm greater than 600MHzkm, effective bandwidth at 850nm and 1300nm respectively greater than 2000MHzkm and 600MHzkm.
2, a kind of manufacture method of improved multimode optical fiber, it may further comprise the steps:
(1) adopt that method deposits the sandwich layer doped glass then at deposited tube inside deposition cladding glass in the pipe, sedimentation velocity from 2.5g/min to 1.5g/min, germanium steam flow from 3% to 60%, the deposition number of plies is 4000 layers, core is 200～500 layers and supports by the arm fluorine, boron;
(2) melt after deposition is finished and contract, melt to control when contracting and melt the shrinkage cavity footpath between 2～8mm diameter, melting the time of contracting is 3-8 hour, feeds C then
2F
6Etchant gas carries out the inner tubal wall corrosion, and the concentration of etchant gas is 20～50%, and etching time was controlled at 20-40 minute, burnt till solid preform at last;
(3) drawing process in addition rotation period be the periodicity rubbing of 20～80 commentaries on classics/rice fiber lengths, the diameter that is drawn into sandwich layer and covering is respectively 50 μ m and 125 μ m, its index distribution by accurate optimization at the 850nm wavelength, the differential mode delay test curve of optical fiber is the curve that rises or descend continuously, and its maximum variation less than 0.22ps/m, completely inject bandwidth at 850nm greater than 1500MHzkm, at 1300nm greater than 600MHzkm, effective bandwidth at 850nm and 1300nm respectively greater than the multimode optical fiber product of 2000 MHzkm and 600MHzkm.
3, according to the manufacture method of a kind of improved multimode optical fiber of claim 2, method is chemical vapour deposition technique or plasma vapor deposition processes in the wherein said pipe.
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| CN100474010C (en) | 2003-07-18 | 2009-04-01 | 株式会社藤仓 | Graded-index multimode fiber and manufacturing method therefor |
| FR2933779B1 (en) * | 2008-07-08 | 2010-08-27 | Draka Comteq France | MULTIMODE OPTIC FIBERS |
| US8565566B2 (en) * | 2011-10-05 | 2013-10-22 | Sumitomo Electric Industries, Ltd. | Multi-mode optical fiber |
| DK3228025T3 (en) * | 2014-12-01 | 2019-11-18 | Draka Comteq Bv | Process for characterizing the performance of an optical multimode fiber link and corresponding method for producing optical multimode fiber links |
-
2002
- 2002-10-17 CN CN 02139181 patent/CN1198157C/en not_active Expired - Lifetime
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