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Patent US4377403A successfully refreshed from Google Patents.
US4377403A
Expired / Lapsed
US
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Method of fabricating a fused single-mode fiber bidirectional coupler
Assignee: United States Department of the Navy
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Filing: 1980-09-29
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Granted: 1983-03-22
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Expires: 2000-09-29
Abstract
Abstract An improvement for the coupling of optical energy in a single-mode fiber ures a stable bidirectional coupling. A method of fabricating a single-mode evanescent field coupler for optical data between two single-mode fibers calls for there first being an etching away of a substantial portion of the claddings about the cores of both single-mode fibers. This etching calls for the immersion of sections of the fibers in an etching solution for a predetermined time with the ends of the exposed sections being carefully masked to create smooth, unscored, tapered transitions. The etched sections of the single-mode fibers are placed in a side-by-side relationship, are longitudinally twisted about each other to assume a closely abutting helical disposition and are secured in place at their ends. A pair of tungsten electrodes are brought into the close proximity of the twisted etched fibers and an arc is initiated. Moving the electrodes along the length of the twisted etched fibers causes the arc to fuse them together to assure a stable configuration and, hence, stable evanescent field coupling. Once the fibers have been fused, a protective envelope encases the fused twisted fibers and it is filled with a liquid having the same index of refraction as the fibers' claddings. Thus, a stable coupler is created that is isolated from outside thermal and mechanical influences.
Inventors
- 👤 Matthew N. McLandrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:18
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/245; G02B6/26; G02B6/28; G02B6/2804; G02B6/2821; G02B6/2835
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
203 words
A method of fabricating a single-mode evanescent coupling of light between two single-mode fibers each provided with a cladding having an outer diameter of approximately one-hundred microns and enclosing a core, comprising: etching away a substantial portion of the cladding about the core of each single-mode fiber along a predetermined length, wherein the step of etching includes exposing the fibers in a hydrofluoric acid solution a sufficient period of time to etch away a sufficient amount of the claddings to assure the evanescent coupling of light, the step of etching includes the inserting of each of the fibers through an opening and the exposing of the inserted portions of the fibers to the etching solution and the etching includes the wax-masking of the fibers where they are inserted into being exposed to the etching solution to present a continuous smooth transition into the etching solution; placing the etched lengths in a side-by-side relationship; twisting the etched lengths longitudinally about each other to assume a closely abutting helical disposition; securing the ends of the etched longitudinally twisted fibers to maintain their closely abutting helical relationship; and fusing the longitudinally twisted etched lengths together in the closely abutting helical shape to assure the evanescent coupling.
Claim 2
Independent Claim
203 words
A method of fabricating a single-mode evanescent coupling of light between two single-mode fibers each provided with a cladding having an outer diameter of approximately one-hundred microns and enclosing a core, comprising: etching away a substantial portion of the cladding about the core of each single-mode fiber along a predetermined length, wherein the step of etching includes exposing the fibers in a hydrofluoric acid solution a sufficient period of time to etch away a sufficient amount of the claddings to assure the evanescent coupling of light, the step of etching includes the inserting of each of the fibers through an opening and the exposing of the inserted portions of the fibers to the etching solution and the etching includes the wax-masking of the fibers where they are inserted into being exposed to the etching solution to present a continuous smooth transition into the etching solution; placing the etched lengths in a side-by-side relationship; twisting the etched lengths longitudinally about each other to assume a closely abutting helical disposition; securing the ends of the etched longitudinally twisted fibers to maintain their closely abutting helical relationship; and fusing the longitudinally twisted etched lengths together in the closely abutting helical shape to assure the evanescent coupling.
Claim 3
Dependent Claim
36 words
A method according to claim 1 in which the wax-masking is done by melting beeswax causing it to flow through the opening through which each of the fibers is inserted and around each of the fibers.
Claim 4
Dependent Claim
37 words
A method according to claim 2 in which the melting causes the wax to flow along the fibers and harden in a smooth transition line so as not to create scores and cracks during the etching process.
Claim 5
Dependent Claim
40 words
A method according to claim 3 further including: encasing the etched, longitudinally twisted and fused fibers in a protective sheath and filling the protective sheath with a fluid having a refractive index that substantially matches the claddings' index of refraction.
Claim 6
Dependent Claim
24 words
A method according to claim 4 in which the step of placing and longitudinally twisting involves etched fibers of approximately two centimeters in length.
Claim 7
Dependent Claim
30 words
A method according to claim 5 in which the step of twisting is the helical interleaving of the fibers of between three to ten turns along the two centimeter length.
Claim 8
Dependent Claim
30 words
A method according to claim 6 in which the step of fusing includes locating the etched longitudinally twisted fibers between a pair of electrodes and initialing an arc between them.
Claim 9
Dependent Claim
31 words
A method according to claim 7 in which the step of fusing includes separating a pair of tungsten electrodes a distance of nearly two millimeters and initialing an arc between them.
Claim 10
Dependent Claim
40 words
A method according to claim 8 in which the step of fusing further includes longitudinally displacing the arcing tungsten electrodes along the etched longitudinally twisted fibers at a predetermined rate to assure fusing of the claddings and the evanescent coupling.
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) | 1986-03-21 | 1986-09-20 | 1987-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-03-21 | 1990-09-20 | 1991-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-03-21 | 1994-09-20 | 1995-03-22 | $7700.00 | Window Closed / Lapsed |