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US4866266A
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Method of measuring polarization and birefringence in single-mode optical fibers
Assignee: Telecom Italia SpA
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Filing: 1988-05-06
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Granted: 1989-09-12
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Expires: 2008-05-06
Abstract
Abstract A constant force perpendicular to the fiber axis is applied to the fiber so as to cause a power coupling from the fundamental mode, which is guided, to a secondary mode which is irradiated, and the intensity of the scattered radiation associated with that secondary mode is measured. Such intensity depends on the local state of polarization. By dispacing the force application point step by step along the fiber axis and by measuring for each point the intensity of the scattered radiation, beat length is obtained as the distance between two consecutive points where the scattered radiation has the same intensity.
Inventors
- 👤 Riccardo Calvani
- 👤 Renato Caponi
- 👤 Francesco Cisternino
- 👤 Gianni Coppa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:43
CPC Classifications
G; G01; G01M; G01M11/00; G01M11/30; G01M11/35
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
112 words
A method of detecting a local state of polarization in a single-mode optical fiber, comprising the steps of: injecting polarized radiation into said optical fiber; applying a force to said fiber in a direction perpendicular to an optical axis thereof and of a strength sufficient to cause a power coupling from a fundamental mode of the radiation guided in said fiber to at least one secondary propagation mode which is irradiated from said optical fiber; and measuring intensity of radiation transversely scattered from said optical fiber as a result of the power coupling and which is proportional to an amplitude of a local polarization component parallel to the direction of force application.
Claim 2
Independent Claim
112 words
A method of detecting a local state of polarization in a single-mode optical fiber, comprising the steps of: injecting polarized radiation into said optical fiber; applying a force to said fiber in a direction perpendicular to an optical axis thereof and of a strength sufficient to cause a power coupling from a fundamental mode of the radiation guided in said fiber to at least one secondary propagation mode which is irradiated from said optical fiber; and measuring intensity of radiation transversely scattered from said optical fiber as a result of the power coupling and which is proportional to an amplitude of a local polarization component parallel to the direction of force application.
Claim 3
Dependent Claim
74 words
The method defined in claim 1, further comprising the steps of: applying to said fiber a second force perpendicular to the direction of application of the first-mentioned force and also perpendicular to said optical axis and of a strength sufficient to cause a power coupling to a secondary mode which is irradiated from said fiber as a second scattered radiation; and measuring laterally of said optical fiber an intensity of said second scattered radiation.
Claim 4
Dependent Claim
27 words
The method defined in claim 2 wherein the intensity measurements are repeated at different points along a length of said optical fiber and at different time instants.
Claim 5
Dependent Claim
45 words
The method defined in claim 3 for measuring birefringence of a high birefringence optical fiber, further comprising the step of determining a distance along said optical fiber between two successive points at which the scattered radiation has the same intensity and representing polarization beat length.
Claim 6
Dependent Claim
29 words
The method defined in claim 4 wherein the measurement is effected using a radiation with a wavelength slightly shorter than a cutoff wavelength of higher-order modes of the fiber.
Claim 7
Dependent Claim
29 words
The method defined in claim 3 wherein the measurement is effected using a radiation with a wavelength slightly shorter than a cutoff wavelength of higher-order modes of the fiber.
Claim 8
Dependent Claim
27 words
The method defined in claim 1 wherein the intensity measurements are repeated at different points along a length of said optical fiber and at different time instants.
Claim 9
Dependent Claim
45 words
The method defined in claim 7 for measuring birefringence of a high birefringence optical fiber, further comprising the seep of determining a distance along said optical fiber between two successive points at which the scattered radiation has the same intensity and representing polarization beat length.
Claim 10
Dependent Claim
29 words
The method defined in claim 8 wherein the measurement is effected using a radiation with a wavelength slightly shorter than a cutoff wavelength of higher-order modes of the fiber.
Claim 11
Dependent Claim
45 words
The method defined in claim 1 for measuring birefringence of a high birefringence optical fiber, further comprising the step of determining a distance along said optical fiber between two successive points at which the scattered radiation has the same intensity and representing polarization beat length.
Claim 12
Dependent Claim
29 words
The method defined in claim 10 wherein the measurement is effected using a radiation with a wavelength slightly shorter than a cutoff wavelength of higher-order modes of the fiber.
Claim 13
Dependent Claim
29 words
The method defined in claim 1 wherein the measurement is effected using a radiation with a wavelength slightly shorter than a cutoff wavelength of higher-order modes of the fiber.
References Cited (Backward Citations)
US4675521A
Cited
US4759624A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-11 | 1993-03-13 | 1993-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-11 | 1997-03-13 | 1997-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-11 | 2001-03-13 | 2001-09-12 | $7700.00 | Window Closed / Lapsed |