EP0307228A2
Expired / Lapsed
EP
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Few-mode/single-mode fiber
Assignee: Corning Glass Works
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Filing: 1988-09-09
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Granted: —
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Expires: 2008-09-09
Abstract
Abstract The present invention pertains to an optical fiber comprising a transparent core having a maximum refractive index n 1 and a radius a surrounded by a layer of transparent cladding material having a refractive index no which is less than n 1- The refractive indices n 1 and no, the radius a, and the refractive index profile of the core are designed such that: (a) Δτ j , the difference between |d(Vb)/dV| j , the normalized delay time of the jth mode and |d(Vb)/dV|0, the normalized delay time of the fundamental mode, is less than about 5 x 10- 2 over a wide range of V-values where j is equal to 1 or 2 and represents the highest order mode that propagates with a low loss, 0 represents the fundamental mode, b is the propagation constant and V is the normalized frequency, and (b) the normalized waveguide dispersion Vd 2 (Vb)/dV 2 is about equal to or less than 0.2 at V-values near Vl, the normalized cutoff frequency of the first higher order mode. A fiber exhibiting characteristics (a) and (b) is capable of providing mode equalized two-mode or three-mode and low dispersion single-mode operation.
Inventors
- 👤 Venkata Adieseshaiah Bhagavatula
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:12
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/028; G02B6/0281; G02B6/02214; G02B6/02219; G02B6/02228; G02B6/0286; G02B6/036; G02B6/03605; G02B6/03611; G02B6/03616; G02B6/03622; G02B6/03627; G02B6/03633; G02B6/03638; G02B6/03644; G02B6/0365; G02B6/03661; G02B6/03666; G02B6/02047
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
186 words
An optical fiber comprising a core of transparent material having a maximum refractive index n and a radius a, and a layer of transparent cladding material on the outer surface of said core, the refractive index no of said cladding being less than n 1 , said fiber being characterized in that the refractive indices n i and no, the radius a, and the refractive index profile of the core are designed such that (a) Δτ j , the difference between |d(Vb)/dV| j , the normalized delay time of the jth mode and |d(Vb)/dV| 0 , the normalized delay time of the fundamental mode, is less than about 5 x 10- 2 over a wide range of V-values where j is equal to 1 or 2 and represents the highest order mode that propagates with a low loss, 0 represents the fundamental mode, b is the propagation constant and V is the normalized frequency, and (b) the normalized waveguide dispersion Vd 2 (Vb)/dV 2 is about equal to or less than 0.2 at V-values near , the normalized cutoff frequency of the first higher order mode.
Claim 2
Dependent Claim
186 words
An optical fiber comprising a core of transparent material having a maximum refractive index n and a radius a, and a layer of transparent cladding material on the outer surface of said core, the refractive index no of said cladding being less than n 1 , said fiber being characterized in that the refractive indices n i and no, the radius a, and the refractive index profile of the core are designed such that (a) Δτ j , the difference between |d(Vb)/dV| j , the normalized delay time of the jth mode and |d(Vb)/dV| 0 , the normalized delay time of the fundamental mode, is less than about 5 x 10- 2 over a wide range of V-values where j is equal to 1 or 2 and represents the highest order mode that propagates with a low loss, 0 represents the fundamental mode, b is the propagation constant and V is the normalized frequency, and (b) the normalized waveguide dispersion Vd 2 (Vb)/dV 2 is about equal to or less than 0.2 at V-values near , the normalized cutoff frequency of the first higher order mode.
Claim 3
Dependent Claim
44 words
An optical fiber in accordance with claim 1 wherein Δτ j is less than about 5 x 10- 2 over a range of V-values equal to about 10% of V near V , where V is the normalized cutoff frequency of the j+1 mode.
Claim 4
Dependent Claim
32 words
An optical fiber in accordance with claim 1 wherein said core comprises a plurality of radially disposed regions, the refractive index profile of at least one of said regions being radially graded.
Claim 5
Dependent Claim
63 words
An optical fiber in accordance with claim 1 wherein said core includes at least one annular region of depressed refractive index, the inner radius a i of the innermost of said at least one region being greater than zero and the maximum radius ao of the outermost of said at least one region of depressed refractive index being less than the radius a.
Claim 6
Dependent Claim
81 words
An optical fiber in accordance with claim 1 wherein said core includes a centrally located region having a maximum refractive index n 1 and a radius ai surrounded by at least two regions of increasing radius having the following refractive indices and radii: (n 2 , a 2 ) and (n 3 , a3), respectively, wherein a3 is greater than a 2 , a 2 is greater than ai, and n 1 and n 3 are greater than n 2 .
Claim 7
Dependent Claim
17 words
An optical fiber in accordance with claim 5 wherein n 1 is greater than n 3 .
Claim 8
Dependent Claim
17 words
An optical fiber in accordance with claim 5 wherein n 3 is greater than n 1 .
Claim 9
Dependent Claim
15 words
An optical fiber in accordance with claim 5 wherein n 2 is greater than no.
Claim 10
Dependent Claim
15 words
An optical fiber in accordance with claim 5 wherein n 2 is less than no.
Claim 11
Dependent Claim
35 words
An optical fiber in accordance with claim 9 wherein said core comprises a further region having a radius a4 which is greater than a3 and a refractive index n 4 which is less than no.
Claim 12
Dependent Claim
17 words
An optical fiber in accordance with claim 10 wherein n 4 is equal to n 2 .
Claim 13
Dependent Claim
81 words
An optical fiber in accordance with claim 1 wherein said core includes a centrally located region having a maximum refractive index n 1 and a radius ai surrounded by at least two regions of increasing radius having the following refractive indices and radii: (n2, a 2 ) and (n 3 , as), respectively, wherein a3 is greater than a 2 , a 2 is greater than a 1 , and n 2 is greater than n 1 and n 3 .
Claim 14
Dependent Claim
14 words
An optical fiber in accordance with claim 12 wherein n 1 is equal tons.
Claim 15
Dependent Claim
18 words
An optical fiber in accordance with claim 12 wherein n 1 is not equal to n 3 .
Claim 16
Dependent Claim
57 words
An optical fiber in accordance with claim 1 wherein said core includes a centrally located region having a maximum refractive index ni and a radius ai surrounded by at least one region having a refractive index n 2 and radius a 2 and wherein ni is greater than no and no is greater than n 2 .
Claim 17
Dependent Claim
59 words
An optical fiber in accordance with claim 1 wherein said core includes a centrally located region having a maximum refractive index n1 and and a radius ai surrounded by a region having a refractive index n 2 and a radius a 2 , and wherein n 1 is greater than n 2 and n 2 is greater than no.
Claim 18
Dependent Claim
35 words
An optical fiber in accordance with claim 16 wherein said core further comprises a third region having a refractive index less than n 2 and no and having a radius greater than a 2 .
Claim 19
Dependent Claim
56 words
An optical fiber in accordance with claim 1 wherein said fiber is characterized in that the refractive indices n and no, the radius a, and the refractive index profile of the core are designed such that said fiber is capable of propagating a single mode signal with zero total dispersion near the zero material dispersion wavelength.
Claim 20
Dependent Claim
85 words
An optical fiber in accordance with claim 18 wherein said fiber is characterized in that said core and said layer of transparent cladding material each comprise silica or silica and a dopant which modifies the refractive index thereof, and wherein the refractive indices ni and no, the radius a, and the refractive index profile of the core are designed such that said fiber is capable of propagating a single mode signal with zero total dispersion at a wavelength within the range of about 1285-1335 nanometers.
Claim 21
Dependent Claim
167 words
An optical fiber comprising a core of transparent material having a maximum refractive index n 1 and a radius a, and a layer of transparent cladding material on the outer surface of said core, the refractive index no of said cladding being less than n 1 , said fiber being characterized in that the refractive indices n1 and no, the radius a, and the refractive index profile of the core are designed such that (a) Δτ j , the difference between |d(Vb)/dV| j , the normalized delay time of the jth mode and |d(Vb)/dV| 0 , the normalized delay time of the fundamental mode, is less than about 5 x 10- 2 over a wide range of V-values where j is equal to 1 or 2 and represents the highest order mode that propagates with a low loss, 0 represents the fundamental mode, b is the propagation constant and V is the normalized frequency, and (b) said fiber exhibits a single-mode dispersion of less than 5 ps/nm-km.
Claim 22
Dependent Claim
167 words
An optical fiber comprising a core of transparent material having a maximum refractive index n 1 and a radius a, and a layer of transparent cladding material on the outer surface of said core, the refractive index no of said cladding being less than n 1 , said fiber being characterized in that the refractive indices n1 and no, the radius a, and the refractive index profile of the core are designed such that (a) Δτ j , the difference between |d(Vb)/dV| j , the normalized delay time of the jth mode and |d(Vb)/dV| 0 , the normalized delay time of the fundamental mode, is less than about 5 x 10- 2 over a wide range of V-values where j is equal to 1 or 2 and represents the highest order mode that propagates with a low loss, 0 represents the fundamental mode, b is the propagation constant and V is the normalized frequency, and (b) said fiber exhibits a single-mode dispersion of less than 5 ps/nm-km.
Claim 23
Dependent Claim
56 words
An optical fiber in accordance with claim 20 wherein said fiber is characterized in that the refractive indices ni and no, the radius a, and the refractive index profile of the core are designed such that said fiber is capable of propagating a single mode signal with zero total dispersion near the zero material dispersion wavelength.
Claim 24
Dependent Claim
86 words
An optical fiber in accordance with claim 21 wherein said fiber is characterized in that said core and said layer of transparent cladding material each comprise silica or silica and a dopant which modifies the refractive index thereof, and wherein the refractive indices n 1 and no, the radius a, and the refractive index profile of the core are designed such that said fiber is capable of propagating a single mode signal with zero total dispersion at a wavelength within the range of about 1285-1335 nanometers.
Claim 25
Dependent Claim
46 words
An optical fiber in accordance with claim 20 wherein Δτ j is less than about 5 x 10- 2 over a range of V-values equal to about 10% of V near V , where V is the normalized cutoff frequency of the j + 1 mode.
Claim 26
Dependent Claim
32 words
An optical fiber in accordance with claim 20 wherein said core comprises a plurality of radially disposed regions, the refractive index profile of at least one of said regions being radially graded.
Claim 27
Dependent Claim
62 words
An optical fiber in accordance with claim 20 wherein said core includes at least one annular region of depressed refractive index, the inner radius a; of the innermost of said at least one region being greater than zero and the maximum radius ao of the outermost of said at least one region of depressed refractive index being less than the radius a.
Claim 28
Dependent Claim
79 words
An optical fiber in accordance with claim 20 wherein said core includes a centrally located region having a maximum refractive index n 1 and a radius a 1 surrounded by at least two regions of increasing radius having the following refractive indices and radii: (n2, a 2 ) and (n 3 , a3), respectively, wherein a3 is greater than a 2 , a2 is greater than a 1 , and n and n3 are greater than n 2 .
Claim 29
Dependent Claim
77 words
An optical fiber in accordance with claim 20 wherein said core includes a centrally located region having a maximum refractive index ni and a radius ai surrounded by at least two regions of increasing radius having the following refractive indices and radii: (n 2 , a 2 ) and (ns, as), respectively, wherein a3 is greater than a 2 , a2 is greater than ai, and n 2 is greater than n 1 and n 3 .
Claim 30
Dependent Claim
59 words
An optical fiber in accordance with claim 20 wherein said core includes a centrally located region having a maximum refractive index n 1 and a radius ai surrounded by at least one region having a refractive index n 2 and radius a 2 and wherein n 1 is greater than no and no is greater than n 2 .
Claim 31
Dependent Claim
59 words
An optical fiber in accordance with claim 20 wherein said core includes a centrally located region having a maximum refractive index n 1 and and a radius ai surrounded by a region having a refractive index n 2 and a radius a 2 , and wherein n 1 is greater than n 2 and n2 is greater than no.
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