ELECTRO-OPTIC SILICON MODULATOR

• US 20100060970A1
• Filed: 09/01/2009
• Published: 03/11/2010
• Est. Priority Date: 09/06/2008
• Status: Active Grant

• Current Assignee: SiFotonics Technologies Co., Ltd.
• Original Assignee: Sifotonics Technologies (USA) Inc.
• Inventors: Chen, Liang
• Granted Patent: US 8,149,493 B2
• Time in Patent Office: Days
• US Class Current: 359/245
• CPC Class Codes: G02F 1/025 in an optical waveguide structure G02F1/017, G02F1/2257 take precedence

Abstract

In a general aspect, a device includes a substrate, a light transmission formed on a top surface of the substrate, a first contact, and a second contact. The light transmission structure includes a first doped region; a second doped region doped oppositely to the first region; a lateral junction between a part of the first doped region and a part of the second doped region, the lateral junction oriented substantially perpendicular to the top surface of the substrate; and a vertical junction between a part of the first doped region and a part of the second doped region, the vertical junction oriented substantially parallel to the top surface of the substrate. The first contact is in electrical contact with the first region and the second contact is in electrical contact with the second region.

Claims

1. A device comprising:

a substrate;

a light transmission structure formed on a top surface of the substrate, the light transmission structure comprising;

a first doped region,

a second doped region, the second region doped oppositely to the first region,

a lateral junction between a part of the first doped region and a part of the

second doped region, the lateral junction oriented substantially perpendicular to the top surface of the substrate, and

a vertical junction between a part of the first doped region and a part of the

second doped region, the vertical junction oriented substantially parallel to the top surface of the substrate;

a first contact in electrical contact with the first region; and

a second contact in electrical contact with the second region.

2. The device of claim 1, wherein the vertical junction is positioned in a region of the light transmission structure in which light propagates.

3. The device of claim 2, wherein the first contact and the second contact are positioned outside of the region in which light propagates.

4. The device of claim 1, wherein the first doped region is N-doped and the second doped region is P-doped.

5. The device of claim 4, wherein the lateral junction is a P-N junction and the vertical junction is a P-N junction.

6. The device of claim 5, wherein a first depletion region exists in the vicinity of the lateral junction and a second depletion region exists in the vicinity of the vertical junction.

7. The device of claim 6 wherein, when a bias is applied between the first contact and the second contact, the first depletion region and the second depletion region change in size.

8. The device of claim 1, wherein a bias applied between the first contact and the second contact induces a change in a refractive index of the light transmission structure.

9. The device of claim 8, wherein the change in the refractive index of the light transmission structure is substantially due to a change in size of a depletion region in the vicinity of the vertical junction.

10. The device of claim 1, wherein a bias applied between the first contact and the second contact induces a change in an optical absorption of the light transmission structure.

11. The device of claim 1, wherein a first part of the first doped region is positioned above a part of the second doped region.

12. The device of claim 1, wherein the light transmission structure supports at least one optical mode.

13. The device of claim 1, wherein the light transmission structure is a rib waveguide comprising:

a first layer disposed on the substrate; and

a rib disposed on the first layer.

14. The device of claim 13, wherein a region of the light transmission structure in which light propagates is located substantially within the rib waveguide.

15. The device of claim 13, wherein the first contact and the second contact are disposed on the first layer and to a side of the rib.

16. The device of claim 1, wherein the light transmission structure is a single mode waveguide.

17. The device of claim 1, wherein the light transmission structure is a multimode waveguide.

18. The device of claim 1, wherein the first contact and the second contact are each disposed to a side of the light transmission structure.

19. The device of claim 1, wherein the light transmission structure is formed of silicon.

20. The device of claim 1, wherein the substrate is silicon.

21. The device of claim 1, wherein the substrate is silicon-on-insulator.

22. The device of claim 1, wherein at least one of the first doped region and the second doped region includes a plurality of sub-regions, each sub-region having a different level of doping.

23. The device of claim 1, wherein the light transmission structure further comprises a plurality of lateral junctions between the first doped region and the second doped region.

24. The device of claim 1, wherein the first contact is in Ohmic contact with the first doped region and the second contact is in Ohmic contact with the second doped region.

25. A method of making a light transmission structure, comprising:

doping a first region of a substrate;

doping a second region of the substrate adjacent to the first region, the second region doped oppositely to the first region;

forming a third region, a first part of the third region above a part of the first

region and a second part of the third region above a part of the second region;

forming a first contact in electrical contact with the first region and positioned to a first side of the third region; and

forming a second contact in electrical contact with the first region and positioned to a second side of the third region.

26. The method of claim 25, wherein forming the third region includes:

depositing a layer of silicon over the first region and the second region;

doping a portion of the layer of silicon, the doped portion overlying a part of the first region and a part of the second region; and

removing the layer of silicon except for the doped portion.

27. The method of claim 26, wherein doping a portion of the layer of silicon includes N-doping the portion of the layer of silicon.

28. The method of claim 26, wherein doping a portion of the layer of silicon includes P-doping the portion of the layer of silicon.

29. The method of claim 25, wherein doping the first region includes N-doping the first region and doping the second region includes P-doping the second region.

30. The method of claim 25, wherein forming the first contact includes:

doping a contact portion of the first region to a doping level higher than a doping level in the first region; and

forming a metal contact connected to the contact portion of the first region.

31. The method of claim 25, wherein forming the second contact includes:

doping a contact portion of the second region to a doping level higher than a doping level in the second region; and

forming a metal contact to the contact portion of the second region.