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US5673342A
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Communication system comprising a low cost optical filter
Assignee: Furukawa Electric North America Inc
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Filing: 1996-05-28
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Granted: 1997-09-30
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Expires: 2016-05-28
Abstract
Abstract An optical fiber communication system according to the invention comprises an optical fiber filter that can be manufactured at low cost and that can be conveniently incorporated into the system, substantially like a conventional fiber jumper. The filter comprises a length L of axially uniform optical fiber selected to have substantially no loss (e.g., <1 dB) at a wavelength λ 1 , and to have relatively high loss (e.g., >20 dB) at a wavelength λ 2 . The length L will typically be less than 100 m. In one embodiment the optical fiber is a single mode optical fiber at λ 1 (e.g., 1.3 μm) that does not have a guided mode at λ 2 (e.g., 1.55 μm). In another embodiment the fiber contains a dopant that does substantially not absorb radiation of wavelength λ 1 , but substantially absorbs at λ 2 . In the second embodiment, λ 1 can be greater than λ 2 . Fiber filters according to the invention can be advantageously used in a variety of communication systems, and exemplary systems are disclosed.
Inventors
- 👤 Katherine Theresa Nelson
- 👤 William Alfred Reed
- 👤 Kenneth Lee Walker
- 👤 Ian Arthur White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:18
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/036; G02B6/03616; G02B6/03622; G02B6/03627; G02B6/24; G02B6/26; G02B6/264; G02B6/266; G02B6/03605; G02B6/03611; G02B6/28; G02B6/293; G02B6/29346; G02B6/29361; G02B6/29368; G02B6/42; G02B6/4201; G02B6/4246
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
186 words
An optical fiber communication system comprising: a) a first source of electromagnetic radiation of a first wavelength λ 1 , first utilization means for electromagnetic radiation of the first wavelength, and a first optical fiber transmission path connecting said first source and said first utilization means; b) a second source of electromagnetic radiation of a second wavelength λ 2 , second utilization means for the electromagnetic radiation of the second wavelength, and a second optical fiber transmission path connecting said second source and said second utilization means, with at least a first portion of said first optical fiber transmission path being included in said second optical fiber transmission path; and c) an optical filter for substantially excluding electromagnetic radiation of the second wavelength from a second portion of the first optical fiber transmission path, said filter being disposed in said first optical fiber transmission path; Characterized In That d) the optical filter comprises a length L of axially essentially uniform optical fiber selected to transmit electromagnetic radiation of the first wavelength substantially without loss, and to at least substantially attenuate electromagnetic radiation of the second wavelength.
Claim 2
Dependent Claim
186 words
An optical fiber communication system comprising: a) a first source of electromagnetic radiation of a first wavelength λ 1 , first utilization means for electromagnetic radiation of the first wavelength, and a first optical fiber transmission path connecting said first source and said first utilization means; b) a second source of electromagnetic radiation of a second wavelength λ 2 , second utilization means for the electromagnetic radiation of the second wavelength, and a second optical fiber transmission path connecting said second source and said second utilization means, with at least a first portion of said first optical fiber transmission path being included in said second optical fiber transmission path; and c) an optical filter for substantially excluding electromagnetic radiation of the second wavelength from a second portion of the first optical fiber transmission path, said filter being disposed in said first optical fiber transmission path; Characterized In That d) the optical filter comprises a length L of axially essentially uniform optical fiber selected to transmit electromagnetic radiation of the first wavelength substantially without loss, and to at least substantially attenuate electromagnetic radiation of the second wavelength.
Claim 3
Dependent Claim
43 words
System according to claim 1, wherein said optical fiber is a silica-based optical fiber that is a single mode optical fiber at λ 1 , and does not support a guided radiation mode at λ 2 , where λ 1 < 2 .
Claim 4
Dependent Claim
118 words
System according to claim 2, wherein λ 1 and λ 2 are approximately 1.3 μm and 1.55 μm, respectively, wherein said optical fiber has a core of diameter in the range 4.0-9.0 μm, having a depressed cladding of outer diameter in the range 2-4 times the core diameter, and having refractive index differences Δ + and Δ - in the range 0.20-0.60% and -0.10 to -0.60%, respectively, where Δ 30 =(n 1 -n 0 )/n 1 , Δ - =(n 2 -n 0 )/n 2 , with n 1 , n 2 and n 0 being, respectively, the refractive index of the core, the refractive index of the depressed cladding, and the refractive index of an outer cladding.
Claim 5
Dependent Claim
46 words
System according to claim 2, wherein the optical fiber comprises a core, a depressed cladding contactingly surrounding the core, and an outer cladding contactingly surrounding the depressed cladding, wherein at least a portion of the outer cladding is selected to absorb radiation of the second wavelength.
Claim 6
Dependent Claim
70 words
System according to claim 1, wherein the optical fiber comprises a core and a cladding contactingly surrounding the core, and wherein at least the core comprises a dopant species that does substantially not absorb radiation of the first wavelength and absorbs radiation of the second wavelength, such that the length L of optical fiber has a loss<1 dB at λ 1 , and a loss>20 dB at λ 2 .
Claim 7
Dependent Claim
11 words
System according to claim 5, wherein λ 1 >λ 2 .
Claim 8
Dependent Claim
30 words
System according to claim 1, comprising system monitoring means, wherein the radiation of the first wavelength is signal radiation and the radiation of the second wavelength is system monitoring radiation.
Claim 9
Dependent Claim
16 words
System according to claim 7, wherein the system monitoring means are optical time domain reflectometry means.
Claim 10
Dependent Claim
23 words
System according to claim 1, wherein both the radiation of the first wavelength and the radiation of the second wavelength are signal radiation.
Claim 11
Dependent Claim
28 words
System according to claim 9, wherein the system is selected to support unidirectional transmission of signal radiation over the first portion of the first optical fiber transmission path.
Claim 12
Dependent Claim
25 words
System according to claim 9, wherein the system comprises bidirectional transmission of signal radiation over the first portion of the first optical fiber transmission path.
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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) | 2000-09-29 | 2001-03-31 | 2001-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-09-29 | 2005-03-31 | 2005-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-09-29 | 2009-03-31 | 2009-09-30 | $7700.00 | Window Closed / Lapsed |