Patent US1557370A successfully refreshed from Google Patents.
US3785718A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low dispersion optical fiber
Assignee: AT&T Inc
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Filing: 1972-09-11
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Granted: 1974-01-15
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Expires: 1992-09-11
Abstract
Abstract The faster propagating, higher order modes are selectively removed from a multimode optical fiber by either attenuating said modes or by coupling the modes out of the fiber core and into the surrounding cladding. In one embodiment the fiber core is surrounded by a low-loss cladding of prescribed thickness, and a refractive index that is no greater than that of any portion of the core. In an alternate embodiment, the core is surrounded by a low-loss cladding whose refractive index is greater than that at the periphery of the core.
Inventors
- 👤 D Gloge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:47
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/028; G02B6/0288
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
149 words
An optical fiber comprising: an inner core material having a graded refractive index which varies continuously from a maximum value at its center to a minimum value at its outer surface; a low-loss cladding of constant refractive index equal to said minimum value surrounding said core; said cladding having a thickness d expressed in terms of the mode numbers and specified attenuation as Alpha m ( square root 2 Delta /a) em(d) ; where em(d) exp( -2nk( Delta M-m/M)1/2d), and is proportional to the field at the outer surface of the cladding for the mth mode out of a total of M modes; n is the refractive index at the core center; a is the core radius; n(1- Delta ) is the refractive index of the cladding; and k 2 pi / lambda is the vacuum wave number of the optical wave energy; and lossy means surrounding said cladding.
Claim 2
Dependent Claim
149 words
An optical fiber comprising: an inner core material having a graded refractive index which varies continuously from a maximum value at its center to a minimum value at its outer surface; a low-loss cladding of constant refractive index equal to said minimum value surrounding said core; said cladding having a thickness d expressed in terms of the mode numbers and specified attenuation as Alpha m ( square root 2 Delta /a) em(d) ; where em(d) exp( -2nk( Delta M-m/M)1/2d), and is proportional to the field at the outer surface of the cladding for the mth mode out of a total of M modes; n is the refractive index at the core center; a is the core radius; n(1- Delta ) is the refractive index of the cladding; and k 2 pi / lambda is the vacuum wave number of the optical wave energy; and lossy means surrounding said cladding.
Claim 3
Dependent Claim
81 words
An optical fiber comprising: an inner core of low-loss material having a uniform refractive index n; an intermediate region surrounding said core comprising a low-loss material having a uniform refractive index n(1- Delta -delta ) less than n, where Delta and delta are positive numbers; said core and said intermediate region being proportioned to support wave energy in a plurality of propagating modes; and an outer cladding surrounding said intermediate region comprising a low-loss material having a refractive index n(1-Delta ).
Claim 4
Dependent Claim
81 words
An optical fiber comprising: an inner core of low-loss material having a uniform refractive index n; an intermediate region surrounding said core comprising a low-loss material having a uniform refractive index n(1- Delta -delta ) less than n, where Delta and delta are positive numbers; said core and said intermediate region being proportioned to support wave energy in a plurality of propagating modes; and an outer cladding surrounding said intermediate region comprising a low-loss material having a refractive index n(1-Delta ).
Claim 5
Dependent Claim
20 words
The optical fiber according to claim 2 including a lossy outer jacket for attenuating wave energy coupled into said cladding.
Claim 6
Dependent Claim
33 words
The optical fiber according to claim 2 wherein delta and Delta are related by delta 1/2 (M-m/M) Delta , where m is the mth mode out of a total of M propagating modes.
Claim 7
Dependent Claim
73 words
An optical fiber comprising: a core of low-loss material whose refractive index varies radially from a maximum value n at its center to a minimum value n(1- Delta - delta ) at its outer surface, where Delta and delta are positive numbers; said core being supportive of wave energy in a plurality of propagating modes; and an outer cladding surrounding said core comprising a low-loss material having a refractive index n(1- Delta ).
Claim 8
Dependent Claim
73 words
An optical fiber comprising: a core of low-loss material whose refractive index varies radially from a maximum value n at its center to a minimum value n(1- Delta - delta ) at its outer surface, where Delta and delta are positive numbers; said core being supportive of wave energy in a plurality of propagating modes; and an outer cladding surrounding said core comprising a low-loss material having a refractive index n(1- Delta ).
Claim 9
Dependent Claim
20 words
The optical fiber according to claim 5 including a lossy out jacket for attenuating wave energy coupled into said cladding.
Claim 10
Dependent Claim
33 words
The optical fiber according to claim 5 where delta and Delta are related by delta 1/2 (M-m/M) Delta , where m is the mth mode out of a total of M propagating modes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |