Light modulation device and filter device

• US 6,646,783 B1
• Filed: 12/07/1999
• Issued: 11/11/2003
• Est. Priority Date: 12/07/1998
• Status: Expired due to Fees

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Fujii, Takashi, Chiku, Shinichiro
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): O'NEILL, GARY WILLIAM
• Application Number:
  US09/455,626
• Time in Patent Office: 1,435 Days
• Field of Search: 359/324, 359/280, 359/246, 359/283, 359/281
• US Class Current: 359/324
• CPC Class Codes: G02F 1/09 based on magneto-optical elements, e.g. exhibiting Faraday effect

Abstract

A light modulation device comprises: a magnetic garnet single crystal having a main surface and an easy magnetization axis in parallel with the main surface; an optical source arranged such that light emitted from the optical source is introduced into the magnetic garnet single crystal and propagates in the magnetic garnet single crystal along a first direction on the main surface; and one or a pair of transducers provided on the main surface of the magnetic garnet single crystal for applying a microwave signal in a region of the magnetic garnet single crystal where the light from the optical source propagates, to modulate the light.

Claims

1. A light modulation device comprising:

a magnetic garnet single crystal having a main surface and an easy magnetization axis in parallel with the main surface;

an optical source arranged such that light emitted from the optical source is introduced into the magnetic garnet single crystal and propagates in the magnetic garnet single crystal along a first direction on the main surface; and

at least one transducer provided at the main surface of the magnetic garnet single crystal for applying a microwave signal in a region of the magnetic garnet single crystal where the light from the optical source propagates, whereby said light is modulated by said microwave signal, wherein the magnetic garnet single crystal has a <

110>

direction or a <

211>

direction as the main surface.

2. The light modulation device according to claim 1, wherein the first direction on the main surface of the magnetic garnet crystal and the easy magnetization axis are parallel with each other.

3. The light modulation device according to claim 2, wherein a magnetic field is applied to the magnetic garnet single crystal along the first direction.

4. The light modulation device according to claim 1, wherein the magnetic garnet single crystal is a magnetic garnet single crystal comprising Y₃Fe₅O₁₂, or at least one of Y and Fe of the Y₃Fe₅O₁₂ being substituted with another element.

5. The light modulation device according to claim 1, further comprising a photodetector disposed for detecting the light propagated in the magnetic garnet single crystal.

6. The light modulation device according to claim 1, wherein said at least one transducer comprises one transducer with a microwave input terminal and a microwave output terminal connected respectively to opposite ends thereof.

7. The light modulation device according to claim 1, wherein said at least one transducer comprises a pair of transducers spaced from each other along said first direction, said pair of transducers having a microwave input terminal and a microwave output terminal connected respectively thereto.

8. A light modulation device comprising:

a magnetic garnet single crystal having a main surface and an easy magnetization axis in parallel with the main surface;

an optical source arranged such that light emitted from the optical source is introduced into the magnetic garnet single crystal and propagates in the magnetic garnet single crystal along a first direction on the main surface; and

at least one transducer provided at the main surface of the magnetic garnet single crystal for applying a microwave signal in a region of the magnetic garnet single crystal where the light from the optical source propagates, whereby said light is modulated by said microwave signal,

wherein the magnetic garnet single crystal is a bulk single crystal.

9. The light modulation device according to claim 8, wherein the magnetic garnet single crystal has a <

110>

direction or a <

211>

direction as the main surface.

10. A light modulation device comprising:

a magnetic garnet single crystal having a main surface and an easy magnetization axis in parallel with the main surface;

an optical source arranged such that light emitted from the optical source is introduced into the magnetic garnet single crystal and propagates in the magnetic garnet single crystal along a first direction on the main surface; and

at least one transducer provided at the main surface of the magnetic garnet single crystal for applying a microwave signal in a region of the magnetic garnet single crystal where the light from the optical source propagates, whereby said light is modulated by said microwave signal,

wherein the magnetic garnet single crystal is an epitaxial thin-film.

11. The light modulation device according to claim 10, wherein the magnetic garnet single crystal is an epitaxial thin-film made using a liquid phase epitaxial method.

12. The light modulation device according to claim 10, wherein the magnetic garnet single crystal has a <

110>

direction or a <

211>

direction as the main surface.

13. A light modulation device comprising:

a magnetic garnet single crystal having a main surface and an easy magnetization axis in parallel with the main surface;

an optical source arranged such that light emitted from the optical source is introduced into the magnetic garnet single crystal and propagates in the magnetic garnet single crystal along a first direction on the main surface; and

at least one transducer provided at the main surface of the magnetic garnet single crystal for applying a microwave signal in a region of the magnetic garnet single crystal where the light from the optical source propagates, whereby said light is modulated by said microwave signal,

wherein said at least one transducer functions as a resonator in response to said microwave signal.

14. The light modulation device according to claim 13, wherein the magnetic garnet single crystal has a <

110>

direction or a <

211>

direction as the main surface.

15. A light modulation device comprising:

a magnetic garnet single crystal having a main surface and an easy magnetization axis in parallel with the main surface;

an optical source arranged such that light emitted from the optical source is introduced into the magnetic garnet single crystal and propagates in the magnetic garnet single crystal along a first direction on the main surface; and

at least one transducer provided at the main surface of the magnetic garnet single crystal for applying a microwave signal in a region of the magnetic garnet single crystal where the light from the optical source propagates, whereby said light is modulated by said microwave signal,

wherein said at least one transducer comprises a gap, so as to function as a resonator in response to said microwave signal.

16. The light modulation device according to claim 15, wherein the magnetic garnet single crystal has a <

110>

direction or a <

211>

direction as the main surface.