US4906068A
Expired / Lapsed
US
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Polarization-maintaining optical fibers for coupler fabrication
Assignee: 3M Co
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Filing: 1988-09-01
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Granted: 1990-03-06
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Expires: 2008-09-01
Abstract
Abstract Polarization-maintaining coupler is made by a biconically-tapered-fused process from two short lengths of an optical fiber, each having a small, oval stress-applying region that substantially contacts the core. The area of the stress-applying region of the optical fiber is less than 10 percent, preferably less than 2 percent, that of the optical fiber and preferably is contiguous with the core. Couplers of highest quality are made from quartz glass fibers having a birefringence between 1 and 3×10 -4 . It is believed that the principal axes of the oval stress-applying regions of those couplers of highest quality have been collinear or parallel. To permit a coupler to be handled, it can be mounted on a quartz glass substrate with the coupler suspended in air and then potted in a cured elastomer.
Inventors
- 👤 Grieg A. Olson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:59
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/2804; G02B6/2821; G02B6/2835; G02B6/10; G02B6/105; G02B6/2843
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
63 words
A polarization-maintaining optical fiber comprising a jacket having an index of refraction substantially lower than that of the core, which jacket includes an oval stress-applying region that has a thermal coefficient of expansion that affords to the fiber a birefringence of from 1 to 3×10 -4 , substantially contacts the core, and has an area less than 10 percent that of the fiber.
Claim 2
Dependent Claim
63 words
A polarization-maintaining optical fiber comprising a jacket having an index of refraction substantially lower than that of the core, which jacket includes an oval stress-applying region that has a thermal coefficient of expansion that affords to the fiber a birefringence of from 1 to 3×10 -4 , substantially contacts the core, and has an area less than 10 percent that of the fiber.
Claim 3
Dependent Claim
30 words
A polarization-maintaining optical fiber as defined in claim 1 wherein the oval stress-applying region affords a birefringence of at least 3 mm beat length at a wavelength of 850 nm.
Claim 4
Dependent Claim
27 words
A polarization-maintaining optical fiber as defined in claim 1 wherein the oval stress-applying region is substantially elliptical and its minor axis approximates the diameter of the core.
Claim 5
Dependent Claim
27 words
A polarization-maintaining optical fiber as defined in claim 3 wherein the minor axis of the elliptical stress-applying region does not exceed twice the diameter of the core.
Claim 6
Dependent Claim
32 words
A polarization-maintaining fiber as defined in claim 4 wherein the diameter of the core is about 5 μm and the maximum diameter of the stress-applying region is from 25 to 40 μm.
Claim 7
Dependent Claim
75 words
A polarization-maintaining coupler comprising two lengths of a biconically-tapered-fused, polarization-maintaining optical fiber, each length comprising an inner core of high index of refraction and a jacket of relatively low index of refraction which includes an oval stress-applying region that has a thermal coefficient of expansion that affords to the fiber a birefringence of from 1 to 3×10 -4 , substantially contacts the core, and has an area less than 10 percent that of the fiber.
Claim 8
Dependent Claim
75 words
A polarization-maintaining coupler comprising two lengths of a biconically-tapered-fused, polarization-maintaining optical fiber, each length comprising an inner core of high index of refraction and a jacket of relatively low index of refraction which includes an oval stress-applying region that has a thermal coefficient of expansion that affords to the fiber a birefringence of from 1 to 3×10 -4 , substantially contacts the core, and has an area less than 10 percent that of the fiber.
Claim 9
Dependent Claim
20 words
A polarization-maintaining coupler as defined in claim 6, the fused portion of which is substantially dumbbell shaped in cross section.
Claim 10
Dependent Claim
48 words
A polarization-maintaining coupler as defined in claim 7 wherein each of the lengths of polarization-maintaining optical fiber has an original diameter and the dumbbell-shaped portion has a waist and the maximum diameter of the coupler waist is from one third to one half the original single fiber diameter.
Claim 11
Dependent Claim
31 words
A polarization-maintaining coupler as defined in claim 7 wherein the maximum diameter of the coupler waist is from 1.5 to 1.8 times the minimum diameter of the coupler through the core.
Claim 12
Dependent Claim
20 words
A polarization-maintaining coupler as defined in claim 9 wherein the fused portion is from 2 to 3 cm in length.
Claim 13
Dependent Claim
95 words
Mount for a polarization-maintaining coupler comprising a pair of biconically-tapered-fused lengths of optical fiber wherein the optical fibers form leads to the fused portion, the leads of which have protective coverings and the fused portion of which is bare, a rigid substrate having approximately the same thermal coefficient of expansion as does the fused portion of the coupler, means for mounting said leads to suspend the fused portion tautly out of contact with both the substrate and the mounting means, and means enclosing the coupler within a protective package with the coupler suspended in air.
Claim 14
Dependent Claim
95 words
Mount for a polarization-maintaining coupler comprising a pair of biconically-tapered-fused lengths of optical fiber wherein the optical fibers form leads to the fused portion, the leads of which have protective coverings and the fused portion of which is bare, a rigid substrate having approximately the same thermal coefficient of expansion as does the fused portion of the coupler, means for mounting said leads to suspend the fused portion tautly out of contact with both the substrate and the mounting means, and means enclosing the coupler within a protective package with the coupler suspended in air.
Claim 15
Dependent Claim
18 words
Mount as defined in claim 11 wherein both the optical fiber and said rigid substrate comprise quartz glass.
Claim 16
Dependent Claim
23 words
Mount as defined in claim 12 wherein said rigid substrate is formed with a channel that is enclosed by a quartz glass cover.
Claim 17
Dependent Claim
29 words
Mount as defined in claim 13 wherein said mounting means comprises an adhesive that bonds the protective coverings of the leads to the substrate without touching the coupler glass.
Claim 18
Dependent Claim
14 words
Mount as defined in claim 14 wherein said enclosing means comprises a cured elastomer.
Claim 19
Dependent Claim
124 words
Method of making a polarization-maintaining coupler comprising the steps of (1) placing side-by-side two short lengths of an optical fiber, each comprising a jacket having an index of refraction substantially lower than that of the core, which jacket includes an oval stress-applying region that has a thermal coefficient of expansion that affords to the fiber a birefringence of from 1 to 3×10 -4 , substantially contacts the core, and has an area of less than 10 percent that of the fiber; (2) aligning the polarization axes of the two fiber lengths, (3) fusing the two fiber lengths together, and (4) while launching light into one of the fiber lengths, drawing the fused lengths until light being emitted from the lengths reaches a predetermined relationship.
Claim 20
Dependent Claim
124 words
Method of making a polarization-maintaining coupler comprising the steps of (1) placing side-by-side two short lengths of an optical fiber, each comprising a jacket having an index of refraction substantially lower than that of the core, which jacket includes an oval stress-applying region that has a thermal coefficient of expansion that affords to the fiber a birefringence of from 1 to 3×10 -4 , substantially contacts the core, and has an area of less than 10 percent that of the fiber; (2) aligning the polarization axes of the two fiber lengths, (3) fusing the two fiber lengths together, and (4) while launching light into one of the fiber lengths, drawing the fused lengths until light being emitted from the lengths reaches a predetermined relationship.
References Cited (Backward Citations)
US4801189A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-05 | 1993-09-04 | 1994-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-05 | 1997-09-04 | 1998-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-05 | 2001-09-04 | 2002-03-06 | $7700.00 | Window Closed / Lapsed |