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USH1155H
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Optical isolator with improved stabiity
Assignee: AT&T Inc
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Filing: 1992-06-08
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Granted: 1993-03-02
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Expires: 2012-06-08
Abstract
Abstract An optical isolator is disclosed which comprises a Faraday rotator disposed between a pair of polarization selective elements (e.g., linear polarizers, birefringent wedges, birefringent plates, etc.). Improvement in isolation stability as a function of variations in temperature and/or signal wavelength are achieved in accordance with the teachings of the present invention by utilizing a Faraday device with a rotation θ less than the conventional 45°. A linear reduction in θ, while resulting in a some signal loss, provides a linear increase in both temperature and wavelength stability.
Inventors
- 👤 Vincent J. Fratello
- 👤 Ralph S. Jameson
- 👤 Steven J. Licht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:48
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/09; G02F1/093; G02F2203/00; G02F2203/04
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
130 words
An optical isolator comprising a first polarization selective element; a second polarization selective element disposed at an angle α with respect to said first polarization selective element; Faraday rotation means disposed in an optical signal path between said first and second elements characterized in that the Faraday rotation means comprises a magnetic field source for generating a magnetic field B of a predetermined intensity; and magneto-optic means comprising a predetermined thickness t and coupled to the magnetic field source, wherein either one or both of said predetermined field intensity and said thickness t are chosen such that said Faraday rotation means exhibits a predetermined stability of isolation with respect to changes in temperature or wavelength by providing a rotation θ of less than 45° to an optical signal passing therethrough.
Claim 2
Dependent Claim
130 words
An optical isolator comprising a first polarization selective element; a second polarization selective element disposed at an angle α with respect to said first polarization selective element; Faraday rotation means disposed in an optical signal path between said first and second elements characterized in that the Faraday rotation means comprises a magnetic field source for generating a magnetic field B of a predetermined intensity; and magneto-optic means comprising a predetermined thickness t and coupled to the magnetic field source, wherein either one or both of said predetermined field intensity and said thickness t are chosen such that said Faraday rotation means exhibits a predetermined stability of isolation with respect to changes in temperature or wavelength by providing a rotation θ of less than 45° to an optical signal passing therethrough.
Claim 3
Dependent Claim
33 words
An optical isolator as defined in claim 1 wherein the Faraday rotation means comprises magneto-optic means which has a predetermined thickness t capable of providing the desired rotation θ of less than 45°.
Claim 4
Dependent Claim
28 words
An optical isolator as defined in claim 1 wherein the predetermined magnetic field intensity is chosen to generate a rotation of less than 45° within the magneto-optical material.
Claim 5
Dependent Claim
31 words
An optical isolator as defined in claim 1 wherein wherein the predetermined thickness t and the magnetic field intensity B are chosen to provide a rotation θ of less than 45°.
Claim 6
Dependent Claim
20 words
An optical isolator as defined in claim 1 wherein the Faraday rotator includes a rare earth iron garnet magneto-optical material.
Claim 7
Dependent Claim
19 words
An optical isolator as defined in claim 5 wherein the rare earth iron garnet material comprises yttrium iron garnet.
Claim 8
Dependent Claim
21 words
An optical oscillator as defined in claim 5 wherein the rare earth iron garnet material comprises bismuth-substituted rare earth iron garnet.
Claim 9
Dependent Claim
15 words
An optical isolator as defined in claim 1 wherein α is chosen such that θ+α≦90°.
Claim 10
Dependent Claim
10 words
An optical isolator as defined in claim 8 wherein α+θ≅90°.
Claim 11
Dependent Claim
10 words
An optical isolator as defined in claim 8 wherein α≅θ.
Claim 12
Dependent Claim
17 words
An optical isolator as defined in claim 1 wherein θ is within the range of aproximately 40°-43°.
Claim 13
Dependent Claim
33 words
An optical isolator as defined in claim 1 wherein the first and second polarization selective elements are chosen from the group consisting of linear polarizers, birefringent wedges, birefringent plates, half-wave plates, quarter-wave plates.
Claim 14
Dependent Claim
22 words
An optical isolator as defined in claim 12 wherein the first and second polarization selective elements comprise first and second linear polarizers.
Claim 15
Dependent Claim
22 words
An optical isolator as defined in claim 12 wherein the first and second polarization selective elements comprise first and second birefringent wedges.
Claim 16
Dependent Claim
93 words
An optical isolator including a Faraday rotator characterized in that the Faraday rotator comprises a magnetic field source for generating a magnetic field B of a predetermined intensity; and magneto-optic means, comprising a predetermined thickness t, coupled to the magnetic field source wherein either one or both of the predetermined field intensity B and predetermined thickness t are chosen such that said Faraday rotator exhibits a predetermined stability of isolation with respect to changes in temperature or wavelength by providing a rotation θ of less than 45° to an optical signal passing therethrough.
Claim 17
Dependent Claim
93 words
An optical isolator including a Faraday rotator characterized in that the Faraday rotator comprises a magnetic field source for generating a magnetic field B of a predetermined intensity; and magneto-optic means, comprising a predetermined thickness t, coupled to the magnetic field source wherein either one or both of the predetermined field intensity B and predetermined thickness t are chosen such that said Faraday rotator exhibits a predetermined stability of isolation with respect to changes in temperature or wavelength by providing a rotation θ of less than 45° to an optical signal passing therethrough.
Claim 18
Dependent Claim
30 words
An optical isolator as defined in claim 15 wherein the Faraday rotator comprises a magneto-optic material having a predetermined thickness t determined to provide a rotation θ less than 45°.
Claim 19
Dependent Claim
29 words
An optical isolator as defined in claim 15 wherein the predetermined magnetic field intensity is chosen to provide the desired rotation of less than 45° within the magneto-optic means.
Claim 20
Dependent Claim
28 words
An optical isolator as defined in claim 15 wherein the predetermined thickness and and magnetic field intensity are chosen to provide a rotation θ of less than 45°.
Claim 21
Dependent Claim
20 words
An optical isolator as defined in claim 15 wherein the Faraday rotator comprises a rare earth iron garnet magneto-optic material.
Claim 22
Dependent Claim
19 words
An optical isolator as defined in claim 19 wherein the rare earth iron garnet comprises yttrium iron garnet (YIG).
Claim 23
Dependent Claim
20 words
An optical isolator as defined in claim 20 wherein the rare earth iron garnet comprises bismuth-substituted rare earth iron garnet.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-03-01 | 1996-08-31 | 1997-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-03-01 | 2000-08-31 | 2001-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-03-01 | 2004-08-31 | 2005-03-02 | $7700.00 | Window Closed / Lapsed |