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US4775209A
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Fiber-optic coupler comprising intertwined monomode fibers of different diameter
Assignee: GEC-MARONI Ltd
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Filing: 1987-02-20
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Granted: 1988-10-04
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Expires: 2007-02-20
Abstract
Abstract A coupler (FIG. 4) comprising a pair of interwined monomode fibers optically coupled along a portion of their length. The diameter of one fiber is significantly smaller than that of the other and this fiber is thus wound helically. A helical pitch not exceeding 10 mm is chosen. For such pitch, the smaller diameter fiber is appreciably longer. The following inequality thus holds: λ.sub.c ·L/ΔL≦L.sub.c : where λ c is the design wavelength, ΔL/L is the difference in fiber lengths per unit length, and L c is the interaction length of the coupler. The signal coupling of the coupler is than a strongly peaked function of wavelength. The coupler is suited to wavelength multiplex/demultiplex applications.
Inventors
- 👤 William J. Stewart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 05:19
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29331; G02B6/29332; G02B6/2804; G02B6/2821; G02B6/2835
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
84 words
In a fiber-optic coupler comprising a pair of intertwined monomode fibers optically coupled along a portion of their length, the fibers being of different diameter; the improvement wherein the fiber of smaller diameter is helically wound about the other fiber to a fine helical pitch such that the following inequality is satisfied: λ c ·L/ΔL≦L c ; where λ c is the design wavelength, ΔL/L is the difference in fiber lengths per unit length, and L c is the interaction length of the coupler.
Claim 2
Dependent Claim
84 words
In a fiber-optic coupler comprising a pair of intertwined monomode fibers optically coupled along a portion of their length, the fibers being of different diameter; the improvement wherein the fiber of smaller diameter is helically wound about the other fiber to a fine helical pitch such that the following inequality is satisfied: λ c ·L/ΔL≦L c ; where λ c is the design wavelength, ΔL/L is the difference in fiber lengths per unit length, and L c is the interaction length of the coupler.
Claim 3
Dependent Claim
28 words
A coupler as claimed in claim 1 wherein the fiber of smaller diameter is a fiber drawn from a fiber nominally identical to the fiber of larger diameter.
References Cited (Backward Citations)
GB1600324A
Cited
GB2018460A
Cited
GB2030318A
Cited
CA1143973A
Cited
US4550974A
Cited
GB2150703A
Cited
US4726643A
Cited
US4647146A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-04 | 1992-04-04 | 1992-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-04 | 1996-04-04 | 1996-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-04 | 2000-04-04 | 2000-10-04 | $7700.00 | Window Closed / Lapsed |