Patent US2283440A successfully refreshed from Google Patents.
US4070091A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical fibre with enhanced security
Assignee: Corning Inc
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Filing: 1976-04-16
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Granted: 1978-01-24
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Expires: 1996-04-16
Abstract
Abstract An optical fibre has a light conducting core surrounded by first and second cladding layers of sequentially lower refractive index. A data-carrying signal can be propagated in the core and a monitoring signal--of a higher modal order than the data signal--can be propagated in the core and first cladding layer. Any attempt to rap the fibre and abstract data information results in aberration of the monitor signal, which can be detected. The monitor signal can be such that resolvable signals cannot be obtained from the data channel by a tap.
Inventors
- 👤 John Charles Wood Taylor
- 👤 Felix Paul Kapron
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:17
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/80; H04B10/85; G; G02; G02B; G02B6/00; G02B6/44; G02B6/4439; G02B6/4469
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
107 words
An optical fibre comprising: a light conducting core having a predetermined minimum refractive index and forming a first light conducting path; a first, light conducting, cladding layer surrounding said core and having a constant refractive index lower than said minimum refractive index of said core and forming with said core a second light conducting path; a second cladding layer over said first cladding layer and having a constant refractive index lower than the refractive index of the first cladding layer; whereby a first signal will propagate only in the core and a second signal will propagate in both the core and the first, light conducting, cladding layer.
Claim 2
Dependent Claim
107 words
An optical fibre comprising: a light conducting core having a predetermined minimum refractive index and forming a first light conducting path; a first, light conducting, cladding layer surrounding said core and having a constant refractive index lower than said minimum refractive index of said core and forming with said core a second light conducting path; a second cladding layer over said first cladding layer and having a constant refractive index lower than the refractive index of the first cladding layer; whereby a first signal will propagate only in the core and a second signal will propagate in both the core and the first, light conducting, cladding layer.
Claim 3
Dependent Claim
32 words
An optical fibre as claimed in claim 1, including a further cladding layer over said second cladding layer, said further cladding layer having a lower refractive index than said second cladding layer.
Claim 4
Dependent Claim
15 words
An optical fibre as claimed in claim 1, said core having a constant refractive index.
Claim 5
Dependent Claim
43 words
An optical fibre as claimed in claim 1, said core having a graded refractive index, said index varying across the radius of the fibre, and being higher at the centre of the fibre and lower at an interface with said first cladding layer.
Claim 6
Dependent Claim
28 words
An optical fibre as claimed in claim 1, comprising two light conducting cores, said cores extending in a spaced apart relationship, said first cladding layer surrounding both cores.
Claim 7
Dependent Claim
62 words
An optical fibre as claimed in claim 1, comprising a plurality of light conducting cores, each core surrounded by a first cladding layer of lower refractive index than the core, said second cladding layer surrounding each clad core, and a further cladding layer over said second cladding layer, said further cladding layer having a lower refractive index than said second cladding layer.
Claim 8
Dependent Claim
34 words
An optical fibre as claimed in claim 1, said fibre having an input end and an output end, and including a mirror at said output end, said mirror aligned with said first cladding layer.
Claim 9
Dependent Claim
53 words
An optical fibre as claimed in claim 7, said mirror extending radially inward from an interface between said first and second cladding layers for a substantial part of the thickness of said first cladding layer and extending radially outward from said interface a mirror part of the thickness of said second cladding layer.
Claim 10
Dependent Claim
87 words
An optical fibre as claimed in claim 7, including data signal means at said input end of said fibre and positioned to launch data signals into said core, data signal detector means at said output end of said fibre, monitor signal means at said input end positioned to launch a monitor signal into said first cladding layer and monitor signal detector means at said input end, said monitor signal detector means arranged to detect monitor signals retroreflected by said mirror at said output end of said fibre.
Claim 11
Dependent Claim
18 words
An optical fibre as claimed in claim 1, including signal scattering centres distributed throughout said first cladding layer.
Claim 12
Dependent Claim
15 words
An optical fibre as claimed in claim 9, said signal scattering centres comprising reflectivity centres.
Claim 13
Dependent Claim
40 words
An optical fibre as claimed in claim 1, including data signal means at an input end of said fibre and positioned to launch data signals into said core, and data signal detector means at an output end of said fibre.
Claim 14
Dependent Claim
43 words
An optical fibre as claimed in claim 12, including monitor signal means at said input end of said fibre and positioned to launch a monitor signal into said first cladding layer, and monitor signal detector means at said output end of said fibre.
Claim 15
Dependent Claim
40 words
An optical fibre as claimed in claim 13, including signal producing means associated with said monitor signal detector means for producing an output signal indicative of said monitor signal, and means responsive to a predetermined variation in said output signal.
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) | 1981-01-23 | 1981-07-25 | 1982-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-23 | 1985-07-25 | 1986-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-23 | 1989-07-25 | 1990-01-24 | $7700.00 | Window Closed / Lapsed |