US5448674A
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Article comprising a dispersion-compensating optical waveguide
Assignee: Furukawa Electric North America Inc
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Filing: 1994-02-16
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Granted: 1995-09-05
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Expires: 2014-02-16
Abstract
Abstract Disclosed is optical fiber that can advantageously be used to compensate chromatic dispersion in an optical fiber communication system, typically a system that is upgraded from 1.3 μm to 1.55 μm operating wavelength (λ op ). The fiber typically has a power law core refractive index profile, a refractive index "trench" surrounding the core, and a refractive index "ridge" surrounding the trench. The refractive index profile of the fiber preferably is designed such that the fiber supports the fundamental mode (LP 01 ), does not support the LP 11 mode but does support the LP 02 mode, all at λ op . At λ op , LP 01 has dispersion more negative than -150 ps/nm·km and, in a preferred embodiment, LP 01 also has negative dispersion slope at λ op . In a further embodiment of the invention the refractive index profile is designed such that the cut-off wavelength of the LP 11 mode is less than that of the higher order mode, typically LP 02 , and less than λ op , such that the fiber does not support propagation of the LP 11 mode. In some preferred embodiments the fiber is designed to have dispersion more negative than about -90 ps/nm·km and loss less than about 0.5 dB/km at λ op ˜1.55 μm.
Inventors
- 👤 Ashish M. Vengsarkar
- 👤 Kenneth L. Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:43
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/02214; G02B6/02219; G02B6/02252; G02B6/02261; G02B6/02047; G02B6/036; G02B6/03616; G02B6/03638; G02B6/03644; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29371; G02B6/29374; H; H04; H04B; H04B10/00; H04B10/25; H04B10/2507; H04B10/2513; H04B10/2525; G02B6/028; G02B6/0281; G02B6/03605; G02B6/03611
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
88 words
An article comprising a length L DC of optical fiber (said fiber to be designated "DC" fiber) designed to support propagation of radiation of wavelength λ op in a fundamental mode and at least one higher order mode, the DC fiber having a refractive index profile, and λ op being about 1.55 μm; CHARACTERIZED IN THAT said refractive index profile is selected such that the radiation in the fundamental mode has dispersion D DC (λ op ) at wavelength λ op that is more negative than -150 ps/nm·km.
Claim 2
Dependent Claim
88 words
An article comprising a length L DC of optical fiber (said fiber to be designated "DC" fiber) designed to support propagation of radiation of wavelength λ op in a fundamental mode and at least one higher order mode, the DC fiber having a refractive index profile, and λ op being about 1.55 μm; CHARACTERIZED IN THAT said refractive index profile is selected such that the radiation in the fundamental mode has dispersion D DC (λ op ) at wavelength λ op that is more negative than -150 ps/nm·km.
Claim 3
Dependent Claim
45 words
The article of claim 1, wherein the refractive index profile is selected such that the DC fiber does not support propagation of the LP 11 mode of the radiation of wavelength λ op and does support propagation of the LP 02 mode of said radiation.
Claim 4
Dependent Claim
122 words
The article of claim 1, wherein the article is an optical fiber communication system that comprises a source of radiation of wavelength λ op , detector means for detecting radiation of wavelength λ op that are spaced from said source of radiation, and an optical fiber transmission path that radiation-transmissively links said source and said detector means, with said optical fiber transmission path comprising said length L DC of DC fiber, and further comprising a length L SM of single mode optical fiber having chromatic dispersion D SM (λ op ) at λ op , with L DC and L SM selected such that L DC ·D DC (λ op )+L SM ·D SM (λ op ) is approximately equal to zero.
Claim 5
Dependent Claim
56 words
The article of claim 3, wherein the refractive index profile is further selected such that the absolute value of (L DC ·D DC (λ)+L SM ·D SM (λ))/(L DC +L SM ) is less than 1.5 ps/nm·km for all wavelengths λ in a wavelength range that is greater than 50 nm and includes λ op .
Claim 6
Dependent Claim
43 words
An article of claim 1, wherein the DC fiber comprises at least one rare earth species capable of stimulated emission at the wavelength λ op , and wherein the article comprises means for coupling pump radiation of wavelength<λ op into the DC fiber.
Claim 7
Dependent Claim
19 words
The article of claim 5, wherein λ op is about 1.55 μm and the rare earth species is Er.
Claim 8
Dependent Claim
177 words
An article comprising a length of optical fiber (said fiber to be designated "DC" fiber) designed to support propagation of radiation of wavelength λ op in a fundamental mode and at least one higher order mode, the DC fiber having a refractive index profile; CHARACTERIZED IN THAT said refractive index profile is selected such that the DC fiber does not support propagation of radiation of wavelength λ op in the LP 11 mode and supports propagation of radiation of wavelength λ op in at least one other higher order mode (designated LP 0m , m=2, 3, . . .), wherein the DC fiber has a core having normalized maximum refractive index difference .increment. c >0, the core contactingly surrounded by a cladding comprising, in outwardly directed sequence, a first cladding region (the "trench") having normalized refractive index difference .increment. 1 <0, a second cladding region (the "ridge") having normalized refractive index difference .increment. 2 selected such that 0<.increment. 2 <.increment. c , and a third cladding region having normalized refractive index difference .increment. 3 <.increment. 2 .
Claim 9
Dependent Claim
177 words
An article comprising a length of optical fiber (said fiber to be designated "DC" fiber) designed to support propagation of radiation of wavelength λ op in a fundamental mode and at least one higher order mode, the DC fiber having a refractive index profile; CHARACTERIZED IN THAT said refractive index profile is selected such that the DC fiber does not support propagation of radiation of wavelength λ op in the LP 11 mode and supports propagation of radiation of wavelength λ op in at least one other higher order mode (designated LP 0m , m=2, 3, . . .), wherein the DC fiber has a core having normalized maximum refractive index difference .increment. c >0, the core contactingly surrounded by a cladding comprising, in outwardly directed sequence, a first cladding region (the "trench") having normalized refractive index difference .increment. 1 <0, a second cladding region (the "ridge") having normalized refractive index difference .increment. 2 selected such that 0<.increment. 2 <.increment. c , and a third cladding region having normalized refractive index difference .increment. 3 <.increment. 2 .
Claim 10
Dependent Claim
41 words
The article of claim 7 wherein m=2, .increment. c >0.015, .increment. 1 <-0.003 and .increment. 3 =0, with the refractive index profile selected such that the cut-off wavelength of LP 11 is less than the cut-off wavelength of LP 02 .
Claim 11
Dependent Claim
31 words
The article of claim 7, wherein said third cladding region extends to the surface of the DC fiber, and wherein .increment. 3 is substantially constant as a function of radial distance.
Claim 12
Dependent Claim
125 words
An article comprising a length L DC of optical fiber (said fiber to be designated "DC" fiber) designed to support propagation of radiation of wavelength λ op in a fundamental mode, the DC fiber having a refractive index profile, cut-off wavelengths respectively for a mode designated LP 11 and a given higher order mode other than LP 11 ; CHARACTERIZED IN THAT said refractive index profile is selected such that i) the cut-off wavelength for the LP 11 mode is less than the cut-off wavelength for said given higher order mode; and ii) the cut-off wavelength for the LP 11 mode is less than λ op , such that the DC fiber does not support propagation of said LP 11 mode at λ op .
Claim 13
Dependent Claim
125 words
An article comprising a length L DC of optical fiber (said fiber to be designated "DC" fiber) designed to support propagation of radiation of wavelength λ op in a fundamental mode, the DC fiber having a refractive index profile, cut-off wavelengths respectively for a mode designated LP 11 and a given higher order mode other than LP 11 ; CHARACTERIZED IN THAT said refractive index profile is selected such that i) the cut-off wavelength for the LP 11 mode is less than the cut-off wavelength for said given higher order mode; and ii) the cut-off wavelength for the LP 11 mode is less than λ op , such that the DC fiber does not support propagation of said LP 11 mode at λ op .
Claim 14
Dependent Claim
41 words
The article of claim 10, wherein said given higher order mode is the LP 02 mode, the cut-off wavelength for the LP 02 mode is in the wavelength range 1.35 μm to 1.60 μm, and λ op is about 1.55 μm.
Claim 15
Dependent Claim
20 words
The article of claim 11, wherein the cut-off wavelength of the LP 02 mode is less than λ op .
Claim 16
Dependent Claim
138 words
The article of claim 12,wherein the article is an optical fiber communication system that comprises a source of radiation of wavelength λ op , detector means for detecting radiation of wavelength λ op that are spaced from said source of radiation, and an optical fiber transmission path that radiation-transmissively links said source and said detector means, with said optical fiber transmission path comprising said length L DC of DC fiber, and further comprising a length L SM of single mode optical fiber having chromatic dispersion D SM (λ op ) at λ op , with L DC and L SM selected such that L DC ·D DC (λ op )+L SM ·D SM (λ op ) is less than 0.2 (L SM ·D SM (λ op )), where L SM is a span length of the communication system.
Claim 17
Dependent Claim
56 words
The article of claim 13, wherein the refractive index profile is further selected such that the absolute value of (L DC ·D DC (λ)+L SM ·D SM (λ))/(L DC +L SM ) is less than 1.5 ps/nm·km for all wavelengths λ in a wavelength range that is greater than 50 nm and includes λ op .
Claim 18
Dependent Claim
46 words
The article of claim 10, wherein said refractive index profile is selected such that the radiation in the fundamental mode has dispersion D DC (λ op ) at wavelength λ op that is more negative than about -90 ps/nm-km, with λ op being about 1.55 μm.
Claim 19
Dependent Claim
102 words
The article of claim 10, wherein the DC fiber has a core having normalized maximum refractive index difference .increment. c >0, the core contactingly surrounded by a cladding comprising, in outwardly directed sequence, a first cladding region (the "trench") having normalized refractive index difference .increment. 1 <0, a second cladding region (the "ridge") having normalized refractive index difference .increment. 2 selected such that 0<.increment. 2 .increment. 2 <.increment. c , and a third cladding region having normalized refractive index difference .increment. 3 <.increment. 2 , wherein said higher order mode is the LP 02 mode, and .increment. c is less than 1.5%.
Claim 20
Dependent Claim
44 words
The article of claim 10, wherein the DC fiber comprises at least one rare earth species capable of stimulated emission at the wavelength λ op , and wherein the article comprises means for coupling pump radiation of wavelength <λ op into the DC fiber.
Claim 21
Dependent Claim
19 words
The article of claim 17, wherein λ op is about 1.55 μm and the rare earth species is ER.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-09-04 | 1999-03-06 | 1999-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-04 | 2003-03-06 | 2003-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-04 | 2007-03-06 | 2007-09-05 | $7700.00 | Window Closed / Lapsed |