US4522473A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Faraday rotator for an optical device
Assignee: NEC Corp
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Filing: 1982-03-22
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Granted: 1985-06-11
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Expires: 2002-03-22
Abstract
Abstract A Faraday rotator has a non-magnetic garnet substrate with a ferrimagnetic garnet film epitaxially grown on the substrate. A magnet induces a magnetic field in the film for rotating the plane of polarization of a light-beam which strikes an end surface of the film at a predetermined angle. The substrate and film are composed of a material wherein the difference (Δ a=a s -a f ) between the lattice constant a s of the substrate and the lattice constant a f of the film satisfies |Δa|≦ 0.001A (angstrom).
Inventors
- 👤 Taketoshi Hibiya
- 👤 Yoshinori Ohta
- 👤 Koichi Matsumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:42
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/09; G02F1/095; G02F1/0009; G02F1/0036
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
113 words
A Faraday rotator comprising: a non-magnetic garnet substrate; a ferrimagnetic garnet film epitaxially grown on the substrate; a light beam impinging upon a surface at an end of said film; and a magnet for inducing a magnetic field parallel to the top surface of said film for rotating a plane of polarization within said film of said light-beam impinging upon said film, said substrate and said film being made of a material having a predetermined absolute value of the difference Δa=a s -a f between the lattice constant a s of said substrate and the lattice constant a f of said film, said predetermined absolute value being no greater than 0.001 Å (angstrom).
Claim 2
Dependent Claim
113 words
A Faraday rotator comprising: a non-magnetic garnet substrate; a ferrimagnetic garnet film epitaxially grown on the substrate; a light beam impinging upon a surface at an end of said film; and a magnet for inducing a magnetic field parallel to the top surface of said film for rotating a plane of polarization within said film of said light-beam impinging upon said film, said substrate and said film being made of a material having a predetermined absolute value of the difference Δa=a s -a f between the lattice constant a s of said substrate and the lattice constant a f of said film, said predetermined absolute value being no greater than 0.001 Å (angstrom).
Claim 3
Dependent Claim
39 words
A Faraday rotator as claimed in claim 1 wherein said substrate, comprises Gd 3 Ga 5 O 12 and said film consists of Gd x Y 3-x Fe 5 O 12 , where x ranges from 0.18 to 0.24.
Claim 4
Dependent Claim
38 words
A Faraday rotator as claimed in claim 1 wherein said substrate comprises Gd 3 Ga 5 O 12 and said film comprises Tb x Y 3-x Fe 5 O 12 , where x ranges from 0.18 to 0.24.
Claim 5
Dependent Claim
38 words
A Faraday rotator as claimed in claim 1 wherein said substrate comprises Dy x Gd 3-x Ga 5 O 12 and said film comprises Y 3 Fe 5 O 12 , where x ranges from 0.32 to 0.37.
Claim 6
Dependent Claim
53 words
A Faraday rotator as claimed in claim 1 wherein said substrate 1 is from a single crystal boule having a predetermined growth axis, said substrate having its normal inclined from a <110> axis toward a predetermined axis by an angle α° which is greater than 0 degrees but no greater than 15 degrees.
Claim 7
Dependent Claim
53 words
A Faraday rotator as claimed in claim 1 wherein said substrate is from a single crystal boule having a predetermined growth axis, said substrate having its normal inclined from a <211> axis toward a predetermined axis by an angle of α° which is greater than 0 degree but no greater than 15 degrees.
Claim 8
Dependent Claim
32 words
A Faraday rotator as claimed in claim 1 wherein said substrate has a growth striation, and the light-beam impinging upon one end surface of said film travels vertically to said growth striation.
Claim 9
Dependent Claim
57 words
A Faraday rotator as claimed in claim 1 wherein said substrate is from a non-magnetic garnet single crystal having a <111> growth axis, said substrate having its normal inclined from a <110> axis toward a <211> axis within a {110} plane by an angle α° which is greater than 0 degree but no greater than 15 degrees.
Claim 10
Dependent Claim
58 words
A Faraday rotator as claimed in claim 1 wherein said substrate is from a non-magnetic garnet single crystal having a <111> growth axis, said substrate having its normal inclined from a <211> axis toward a <110> axis within a {211} plane by an angle of α° which is greater than 0 degree but no greater than 15 degrees.
Claim 11
Dependent Claim
39 words
The Faraday rotator of claim 1 wherein said substrate is taken from the group consisting of Gd 3 Ga 5 O 12 and Dy x Gd 3-x Ga 5 O 12 , where x ranges from 0.032 to 0.37.
Claim 12
Dependent Claim
49 words
The Faraday rotator of claim 1 wherein said film is taken from the group consisting of Y 3 Fe 5 O 12 , Gd x Y 3-x Fe 5 O 12 , and Tb x Y 3-x Fe 5 O 12 , where x ranges from 0.18 to 0.24.
References Cited (Backward Citations)
US4222668A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-10 | 1988-12-10 | 1989-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-10 | 1992-12-10 | 1993-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-10 | 1996-12-10 | 1997-06-11 | $7700.00 | Window Closed / Lapsed |