US4413879A
Expired / Lapsed
US
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Method and apparatus for side launch excitation of selected modes in graded-index optical fibers
Assignee: National Security Agency
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Filing: 1979-10-15
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Granted: 1983-11-08
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Expires: 1999-10-15
Abstract
Abstract An optical fiber having a parabolic-index profile is etched to a taper below the cladding layer. A prism contacts the taper along its length within the etched portion of the fiber, and coherent light is transmitted through the prism into the fiber. Selective control of the light beam entry angle, entry position along the taper, and control of the etching depth allows excitation of specific modes within the fiber and maximization of coupling efficiency.
Inventors
- 👤 John W. Berthold, III
- 👤 Paul S. Szczepanek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:08
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/34; G02B6/42; G02B6/4201; G02B6/4204; G02B6/4206; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
An apparatus for exciting a selected mode in a graded-index optical fiber, comprising: a graded-index multimode optical fiber which has been etched to a taper below the cladding layer; a coupling medium having an index of refraction greater than that of the fiber cladding and contacting the tapered portion of the fiber; and a source of light directed toward the coupling medium such that the light beam passes through the medium into the fiber.
Claim 2
Independent Claim
74 words
An apparatus for exciting a selected mode in a graded-index optical fiber, comprising: a graded-index multimode optical fiber which has been etched to a taper below the cladding layer; a coupling medium having an index of refraction greater than that of the fiber cladding and contacting the tapered portion of the fiber; and a source of light directed toward the coupling medium such that the light beam passes through the medium into the fiber.
Claim 3
Dependent Claim
12 words
The apparatus of claim 1 wherein said coupling medium is a prism.
Claim 4
Dependent Claim
14 words
The apparatus of claim 2 wherein said light source is a coherent light source.
Claim 5
Independent Claim
59 words
A method for exciting a selected mode in a graded-index optical fiber, comprising: etchng a graded-index multimode optical fiber to a taper below the cladding layer; directing a coherent beam of light into the fiber through the side of the etched portion, and adjusting the angle of incidence of said beam to excite a predetermined mode in said fiber.
Claim 6
Independent Claim
59 words
A method for exciting a selected mode in a graded-index optical fiber, comprising: etchng a graded-index multimode optical fiber to a taper below the cladding layer; directing a coherent beam of light into the fiber through the side of the etched portion, and adjusting the angle of incidence of said beam to excite a predetermined mode in said fiber.
Claim 7
Dependent Claim
22 words
The method of claim 4 wherein said directing includes directing a beam of light into a prism adjacent to said etched portion.
Claim 8
Dependent Claim
23 words
The method of claim 5 including the further step of adjusting the position of the prism along said taper to maximize coupling efficiency.
Claim 9
Dependent Claim
30 words
The method of claim 5 including the further step of varying the optical fiber angle with respect to the plane of incidence of the light beam to vary the mode.
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) | 1986-11-07 | 1987-05-09 | 1987-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-07 | 1991-05-09 | 1991-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-07 | 1995-05-09 | 1995-11-08 | $7700.00 | Window Closed / Lapsed |