US4556314A
Expired / Lapsed
US
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Dispersion determining method and apparatus
Assignee: Nokia Bell Labs
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Filing: 1983-08-31
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Granted: 1985-12-03
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Expires: 2003-08-31
Abstract
Abstract The dispersion in an optical fiber is determined using an intensity or optical signal envelope cross-correlation. Light from an optical source is injected into two transmission paths in which the relative delay can be varied. At least one path comprises the optical fiber whose dispersion is to be determined. Each path provides an output signal having a signal envelope. These envelopes are then cross-correlated for a number of wavelengths to provide a measurement of group delay from which the dispersion is determined.
Inventors
- 👤 Julian Stone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:51
CPC Classifications
G; G01; G01M; G01M11/00; G01M11/30; G01M11/33; G01M11/338; G01M11/333; G01N; G01N21/00; G01N21/17; G01N21/41
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
88 words
Apparatus for use in determining the dispersion of an optical fiber comprising first and second signal paths, at least a portion of each of said paths being capable of carrying optical signals, at least one of said paths including said optical fiber, means for directing an optical signal from a source into each of said paths, each of said paths including a photodetector for generating a detector output signal having a signal envelope, means for varying the relative delay along said paths, and means for cross-correlating said envelopes.
Claim 2
Dependent Claim
88 words
Apparatus for use in determining the dispersion of an optical fiber comprising first and second signal paths, at least a portion of each of said paths being capable of carrying optical signals, at least one of said paths including said optical fiber, means for directing an optical signal from a source into each of said paths, each of said paths including a photodetector for generating a detector output signal having a signal envelope, means for varying the relative delay along said paths, and means for cross-correlating said envelopes.
Claim 3
Dependent Claim
19 words
The apparatus of claim 1 wherein one of said paths comprises a reference transmission medium whose dispersion is known.
Claim 4
Dependent Claim
14 words
The apparatus of claim 2 wherein said reference medium is a second optical fiber.
Claim 5
Dependent Claim
13 words
The apparatus of claim 2 wherein said reference medium is an air path.
Claim 6
Dependent Claim
13 words
The apparatus of claim 1 wherein said source is an incoherent light source.
Claim 7
Dependent Claim
21 words
The apparatus of claim 5 wherein said directing means includes filtering means so that said optical signal has a preselected wavelength.
Claim 8
Dependent Claim
24 words
The apparatus of claim 5 wherein each of said paths comprises filtering means so that each of said output signals has a preselected wavelength.
Claim 9
Dependent Claim
18 words
The apparatus of claim 1 wherein said means for varying the relative delay is an optical delay line.
Claim 10
Dependent Claim
18 words
The apparatus of claim 1 wherein said means for varying the relative delay is an electrical delay line.
Claim 11
Independent Claim
88 words
A method for use in determining the dispersion of an optical fiber, said method comprising the steps of (a) providing light of a first selected wavelength in two signal conducting paths, at least one of said paths comprising said optical fiber and each of said paths including a photodetector for generating a detector output signal having a signal envelope, (b) varying the relative delay along said paths, (c) cross-correlating said envelopes, and (d) repeating steps a, b, and c for light at at least a second selected wavelength.
Claim 12
Independent Claim
88 words
A method for use in determining the dispersion of an optical fiber, said method comprising the steps of (a) providing light of a first selected wavelength in two signal conducting paths, at least one of said paths comprising said optical fiber and each of said paths including a photodetector for generating a detector output signal having a signal envelope, (b) varying the relative delay along said paths, (c) cross-correlating said envelopes, and (d) repeating steps a, b, and c for light at at least a second selected wavelength.
Claim 13
Dependent Claim
18 words
The method of claim 10 wherein one of said paths comprises a reference medium whose dispersion is known.
Claim 14
Dependent Claim
14 words
The method of claim 11 wherein said reference medium is a second optical fiber.
Claim 15
Dependent Claim
13 words
The method of claim 11 wherein said reference medium is an air path.
Claim 16
Dependent Claim
91 words
Apparatus for use in determining the dispersion of an optical fiber comprising first and second signal paths, at least a portion of each of said paths being capable of carrying optical signals, at least one of said paths being adapted to receive said optical fiber, means for directing an optical signal from a source into each of said paths, each of said paths including a photodetector for generating a detector output signal having a signal envelope, means for varying the relative delay along said paths, and means for cross-correlating said envelopes.
Claim 17
Dependent Claim
91 words
Apparatus for use in determining the dispersion of an optical fiber comprising first and second signal paths, at least a portion of each of said paths being capable of carrying optical signals, at least one of said paths being adapted to receive said optical fiber, means for directing an optical signal from a source into each of said paths, each of said paths including a photodetector for generating a detector output signal having a signal envelope, means for varying the relative delay along said paths, and means for cross-correlating said envelopes.
References Cited (Backward Citations)
US4411520A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1988-12-02 | 1989-06-03 | 1989-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-02 | 1993-06-03 | 1993-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-02 | 1997-06-03 | 1997-12-03 | $7700.00 | Window Closed / Lapsed |