US5237445A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical isolator
Assignee: Shimadzu Corp
•
Filing: 1991-11-20
•
Granted: 1993-08-17
•
Expires: 2011-11-20
Abstract
Abstract An optical isolator having a combination of rutile plates or other birefringent crystals and Faraday elements. This optical isolator includes, arranged in the stated order along an optical axis, a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45°; a second birefringent crystal having an optic axis rotated 45° with respect to the first birefringent crystal, and a thickness √2 times a thickness of the first birefringent crystal; a third birefringent crystal having an optic axis rotated 135° with respect to the first birefringent crystal, and a thickness √2 times the thickness of the first birefringent crystal; a second Faraday element for rotating the plane of polarization 45°; and a fourth birefringent crystal having an optic axis rotated 180° with respect to the first birefringent crystal, and a thickness equal to the thickness of the first birefringent crystal. Two polarized light components passing through this optical isolator have the same optical path length.
Inventors
- 👤 Nobuyuki Kuzuta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:37
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/09; G02F1/093; G02F2203/00; G02F2203/06
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
140 words
An optical isolator having a combination of birefringent crystals and Faraday elements, said optical isolator comprising, arranged along an optical axis: a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45 degrees; a second birefringent crystal having an optic axis rotated 45 degrees with respect to said first birefringent crystal, and a thickness √2 times a thickness of said first birefringent crystal; a third birefringent crystal having an optic axis rotated 135 degrees with respect to said first birefringent crystal, and a thickness √2 times the thickness of said first birefringent crystal; a second Faraday element for rotating the plane of polarization 45 degrees; and a fourth birefringent crystal having an optic axis rotated 180 degrees with respect to said first birefringent crystal, and a thickness equal to the thickness of said first birefringent crystal.
Claim 2
Dependent Claim
140 words
An optical isolator having a combination of birefringent crystals and Faraday elements, said optical isolator comprising, arranged along an optical axis: a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45 degrees; a second birefringent crystal having an optic axis rotated 45 degrees with respect to said first birefringent crystal, and a thickness √2 times a thickness of said first birefringent crystal; a third birefringent crystal having an optic axis rotated 135 degrees with respect to said first birefringent crystal, and a thickness √2 times the thickness of said first birefringent crystal; a second Faraday element for rotating the plane of polarization 45 degrees; and a fourth birefringent crystal having an optic axis rotated 180 degrees with respect to said first birefringent crystal, and a thickness equal to the thickness of said first birefringent crystal.
Claim 3
Dependent Claim
14 words
An optical isolator as defined in claim 1, wherein said birefringent crystals are rutile.
Claim 4
Dependent Claim
14 words
An optical isolator as defined in claim 1, wherein said birefringent crystals are sapphire.
Claim 5
Dependent Claim
14 words
An optical isolator as defined in claim 1, wherein said birefringent crystals ar calcite.
Claim 6
Dependent Claim
153 words
An optical isolator having a combination of birefringent crystals and Faraday elements, said optical isolator comprising, arranged along an optical axis: a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45 degrees; a second birefringent crystal having an optic axis rotated 45 degrees with respect to said first birefringent crystal, and a thickness (1+√2 ) times a thickness of said first birefringent crystal; a second Faraday element for rotating the plane of polarization 45 degrees; a third birefringent crystal having an optic axis rotated 90 degrees with respect to said first birefringent crystal, and a thickness (1+√2) times the thickness of said first birefringent crystal; a third Faraday element for rotating the plane of polarization 45 degrees; and a fourth birefringent crystal having an optic axis rotated 135 degrees with respect to said first birefringent crystal, and a thickness equal to the thickness of said first birefringent crystal.
Claim 7
Dependent Claim
153 words
An optical isolator having a combination of birefringent crystals and Faraday elements, said optical isolator comprising, arranged along an optical axis: a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45 degrees; a second birefringent crystal having an optic axis rotated 45 degrees with respect to said first birefringent crystal, and a thickness (1+√2 ) times a thickness of said first birefringent crystal; a second Faraday element for rotating the plane of polarization 45 degrees; a third birefringent crystal having an optic axis rotated 90 degrees with respect to said first birefringent crystal, and a thickness (1+√2) times the thickness of said first birefringent crystal; a third Faraday element for rotating the plane of polarization 45 degrees; and a fourth birefringent crystal having an optic axis rotated 135 degrees with respect to said first birefringent crystal, and a thickness equal to the thickness of said first birefringent crystal.
Claim 8
Dependent Claim
14 words
An optical isolator as defined in claim 5 wherein said birefringent crystals are rutile.
Claim 9
Dependent Claim
14 words
An optical isolator as defined in claim 5, wherein said birefringent crystals are sapphire.
Claim 10
Dependent Claim
14 words
An optical isolator as defined in claim 5, wherein said birefringent crystals are calcite.
References Cited (Backward Citations)
US4178073A
Cited
JPS5624314A
Cited
US4548478A
Cited
JPS5850512A
Cited
US4712880A
Cited
JPS59176721A
Cited
JPS60130934A
Cited
JPH02188715A
Cited
US5033830A
Cited
US5052786A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-16 | 1997-02-15 | 1997-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-16 | 2001-02-15 | 2001-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-16 | 2005-02-15 | 2005-08-17 | $7700.00 | Window Closed / Lapsed |