EP0512783A2
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EP
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Optical isolator with improved stability
Assignee: AT&T Inc
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Filing: 1992-05-05
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Granted: —
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Expires: 2012-05-05
Abstract
Abstract An optical isolator (10) is disclosed which comprises a Faraday rotator (12) disposed between a pair of polarization selective elements (14, 16). 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 theta less than the conventional 45 DEG . A linear reduction in theta , while resulting in a some signal loss, provides a linear increase in both temperature and wavelength stability. <IMAGE>
Inventors
- 👤 Vincent Jerome Fratello
- 👤 Ralph Stephen Jameson
- 👤 Steven Joy Licht
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:14
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/09; G02F1/093; G02F2203/00; G02F2203/04
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
67 words
An optical isolator comprising a first polarization selective element (14); a second polarization selective element (16) disposed at an angle α with respect to said first polarization selective element; and Faraday rotation means (12) disposed in an optical signal path between said first and second elements CHARACTERIZED IN THAT the Faraday rotation means provides a rotation ϑ of less than 45° to an optical signal passing therethrough.
Claim 2
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 3
Dependent Claim
67 words
An optical isolator as defined in claim 1 wherein the Faraday rotation means comprises a magnetic field source for generating a magnetic field B of a predetermined intensity; and magneto-optic means coupled to the magnetic field source and exhibiting a Faraday rotation proportional to said magnetic field, wherein the predetermined magnetic field intensity is chosen to generate a rotation of less than 45° within said magneto-optic material.
Claim 4
Dependent Claim
62 words
An optical isolator as defined in claim 1 wherein 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 said predetermined thickness and magnetic field intensity are chosen to provide a rotation ϑ of less than 45°.
Claim 5
Dependent Claim
20 words
An optical isolator as defined in claim 1 wherein the Faraday rotator includes a rare earth iron garnet magneto-optic material.
Claim 6
Dependent Claim
19 words
An optical isolator as defined in claim 5 wherein the rare earth iron garnet material comprises yttrium iron garnet.
Claim 7
Dependent Claim
21 words
An optical isolator as defined in claim 5 wherein the rare earth iron garnet material comprises bismuth-substituted rare earth iron garnet.
Claim 8
Dependent Claim
19 words
An optical isolator as defined in claim 1 wherein α is chosen such that ϑ + α ≦ 90°.
Claim 9
Dependent Claim
14 words
An optical isolator as defined in claim 8 wherein α + ϑ ≅ 90°.
Claim 10
Dependent Claim
12 words
An optical isolator as defined in claim 8 wherein α ≅ ϑ.
Claim 11
Dependent Claim
17 words
An optical isolator as defined in claim 1 wherein ϑ is within the range of approximately 40-43°.
Claim 12
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 13
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 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 birefringent wedges.
References Cited (Backward Citations)
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