Method of making a multimode optical fiber
First Claim
Patent Images
1. A method of making a multimode optical fiber comprisingmeasuring a refractive index profile n(r) of an optical fiber core preform at a first wavelength λ
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selecting a core delta Δ
fit, core radius afit and core shape parameter α
fit that minimize a refractive index difference between n(r) and f(r)=n (0)[1−
2Δ
fit(r/afit)α
fit]1/2 as a function of radius r;
selecting a target optical fiber core shape parameter α
fcr different than α
fit;
selecting a draw tension T that produces the target optical fiber core shape parameter α
fcr from α
fit;
calculating a refractive index ncl at λ
of a cladding material when the draw tension T is applied to the cladding material;
calculating a relative refractive index profile of a modeled multimode optical fiber comprising optical fiber core shape parameter α
fcr relative to ncl;
calculating a target optical fiber core radius at such that a calculated relative time delay at λ
of an outermost mode group guidable by the modeled multimode optical fiber is minimized;
depositing the cladding material on the optical fiber core preform to form an optical fiber preform; and
drawing a multimode optical fiber from the optical fiber preform at the tension T such that the multimode optical fiber comprises an outside diameter of 125±
2 μ
m, a core radius equal to at and a core shape parameter between 1.8 and 2.3.
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Abstract
A method of making a multimode optical fiber is disclosed. In one embodiment the method includes calculating a core radius that maximizes the bandwidth of the multimode optical fiber wherein the effect of draw tension is accounted for. The embodiments herein illustrate how core radius can be tuned so the time delay of the outermost guided mode group is reduced. The resultant core radius may be targeted for a value off-nominal from what would be expected for a particular commercial optical fiber type.
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Citations
14 Claims
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1. A method of making a multimode optical fiber comprising
measuring a refractive index profile n(r) of an optical fiber core preform at a first wavelength λ - ;
selecting a core delta Δ
fit, core radius afit and core shape parameter α
fit that minimize a refractive index difference between n(r) and f(r)=n (0)[1−
2Δ
fit(r/afit)αfit ]1/2 as a function of radius r;selecting a target optical fiber core shape parameter α
fcr different than α
fit;selecting a draw tension T that produces the target optical fiber core shape parameter α
fcr from α
fit;calculating a refractive index ncl at λ
of a cladding material when the draw tension T is applied to the cladding material;calculating a relative refractive index profile of a modeled multimode optical fiber comprising optical fiber core shape parameter α
fcr relative to ncl;calculating a target optical fiber core radius at such that a calculated relative time delay at λ
of an outermost mode group guidable by the modeled multimode optical fiber is minimized;depositing the cladding material on the optical fiber core preform to form an optical fiber preform; and drawing a multimode optical fiber from the optical fiber preform at the tension T such that the multimode optical fiber comprises an outside diameter of 125±
2 μ
m, a core radius equal to at and a core shape parameter between 1.8 and 2.3. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of manufacturing a multimode optical fiber comprising:
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measuring a refractive index profile of a core preform at a first wavelength λ
to obtain a shape parameter α
pcr and a maximum relative refractive index difference Δ
pcr of the core preform;determining a target draw tension that produces the target optical fiber shape parameter α
fcr from α
pcr;calculating an optical fiber core relative refractive index difference Δ
fcr at λ
obtained from Δ
pcr with the target draw tension;using Δ
fcr to calculate a target core radius at of a modeled multimode optical fiber that minimizes a relative time delay Δ
τ
of an outermost mode group guidable by the modeled multimode optical fiber at λ
;forming an outer cladding over the core preform to form an optical fiber preform; and drawing a multimode optical fiber comprising a core and a cladding from the optical fiber preform at the target draw tension such that the multimode optical fiber comprises an outside diameter of 125±
2 μ
m, a core radius equal to at and a maximum relative refractive index difference of the multimode optical fiber core relative to the cladding is equal to or less than 1.05% and at is equal to or greater than 23.0 μ
m. - View Dependent Claims (9, 10)
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11. A method of making a multimode optical fiber comprising:
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measuring a refractive index profile n(r) of an optical fiber core preform at a wavelength λ
of 850 nm;selecting a core delta Δ
fit, core radius afit and core shape parameter α
fit that minimize a refractive index difference between n(r) and f(r)=n (0)[1−
2Δ
fit(r/afit)αfit ]1/2 from r=0.15afit to r=0.95afit;selecting a draw tension T that produces a target optical fiber core shape parameter α
fcr from α
fit;calculating a refractive index ncl at λ
of a cladding material when the draw tension T is applied to the cladding material;using ncl to calculate a relative refractive index profile Δ
fcr(r) of a modeled multimode optical fiber core having optical fiber core shape parameter α
fcr, where - View Dependent Claims (12, 13, 14)
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Specification
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Current AssigneeCorning Incorporated
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Original AssigneeCorning Incorporated
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InventorsBickham, Scott Robertson, Kogan, Oleksandr, Li, Ming-Jun, Mishra, Snigdharaj Kumar, Tandon, Pushkar
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Primary Examiner(s)HOFFMANN, JOHN M
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Application NumberUS13/331,610Publication NumberTime in Patent Office1,778 DaysField of SearchUS Class Current1/1CPC Class CodesC03B 2201/12 doped with fluorine C03B220...C03B 2201/28 doped with phosphorusC03B 2201/31 doped with germaniumC03B 2201/32 doped with aluminium C03B22...C03B 2203/23 Double or multiple optical ...C03B 2203/26 Parabolic or graded index [...C03B 2205/40 Monitoring or regulating th...C03B 37/01413 Reactant delivery systems C...C03B 37/0253 Controlling or regulating f...G02B 6/0288 Multimode fibre, e.g. grade...Y02P 40/57 Improving the yield, e-g- r...
