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Patent US4447127A successfully refreshed from Google Patents.
US4447127A
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US
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Low loss single mode fiber
Assignee: AT&T Inc
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Filing: 1982-04-09
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Granted: 1984-05-08
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Expires: 2002-04-09
Abstract
Abstract In a double-clad, single mode fiber with depressed inner cladding, reduced losses at the longer wavelengths are realized when the ratio of the radius of the inner cladding to the radius of the core is at least 6.5 to 1.
Inventors
- 👤 Leonard G. Cohen
- 👤 Wanda L. Mammel
- 👤 Dietrich Marcuse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:14
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/036; G02B6/03616; G02B6/03622; G02B6/03627
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
70 words
A single mode fiber comprising: an inner core region having a refractive index n c and a radius r c surrounded by a first, inner cladding having a refractive index n 1 and an outer radius r 1 , and a second, outer cladding having a refractive index n 2 , where n 1 <n 2 <n c ; and the ratio r 1 :r c is at least 6.5:1.
Claim 2
Dependent Claim
70 words
A single mode fiber comprising: an inner core region having a refractive index n c and a radius r c surrounded by a first, inner cladding having a refractive index n 1 and an outer radius r 1 , and a second, outer cladding having a refractive index n 2 , where n 1 <n 2 <n c ; and the ratio r 1 :r c is at least 6.5:1.
Claim 3
Dependent Claim
46 words
The fiber according to claim 1 wherein the fractional difference Δ between the refractive index of the core and the second cladding, given by ##EQU4## and the fractional difference Δ' between the refractive indices of the first and second claddings, given by ##EQU5## are such that
Claim 4
Dependent Claim
3 words
|Δ|+|Δ'|=0. 5 percent.
Claim 5
Dependent Claim
3 words
|Δ|+|Δ'|=0. 5 percent.
Claim 6
Dependent Claim
9 words
The fiber according to claim 2 wherein Δ≦0.4 percent.
Claim 7
Dependent Claim
21 words
The fiber according to claim 1 where said fiber is single mode over the range of wavelengths greater than 1.3 μm.
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) | 1987-05-08 | 1987-11-07 | 1988-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-08 | 1991-11-07 | 1992-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-08 | 1995-11-07 | 1996-05-08 | $7700.00 | Window Closed / Lapsed |