Optical coupling structure

• US 20070253663A1
• Filed: 04/26/2006
• Published: 11/01/2007
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Keyser, Thomas, Hughes, Grenville
• Granted Patent: US 7,454,102 B2
• Time in Patent Office: Days
• US Class Current: 385/36
• CPC Class Codes: G02B 6/12 of the integrated circuit kind electric integrated circuits H01L27/00
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/42 Coupling light guides with opto-electronic elements
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52

Abstract

An optoelectronic coupling structure, a method of manufacture, and a method of operation are described. The optical coupling structure includes a waveguide that is formed within a device layer of an SOI substrate. A prism is located on a bottom side of the SOI substrate. A BOX layer of the SOI substrate, which is interposed between the prism and the waveguide, serves as a spacer region, which promotes an optical coupling of the prism to the waveguide. By positioning the prism below the waveguide, an optoelectronic IC may more readily accommodate a prism. The prism may be directly fabricated in a bulk layer of the SOI substrate or directly bonded to a bottom side surface of the BOX layer.

Claims

1. An optical coupling structure, comprising:

a silicon-on-insulator substrate comprising a top side and a bottom side, wherein a buried oxide layer is interposed between the top side and the bottom side;

a wave guide formed on the top side; and

a prism formed on the bottom side, wherein a portion of the buried oxide layer serves as a spacer between the prism and the waveguide.

2. The optical coupling structure as in claim 1, wherein the portion of the buried oxide layer promotes an optical coupling between the prism and the waveguide.

3. The optical coupling structure as in claim 1, wherein the waveguide is formed in a device layer and the prism is formed in a bulk layer.

4. The optical coupling structure as in claim 3, wherein the bulk layer has a first refractive index (n₁), the buried oxide layer has a second refractive index (n₂), and the device layer has third refractive index (n₃), and wherein n₁≧

n₃>

n₂.

5. The optical coupling structure as in claim 1, wherein a thickness of the buried oxide layer is less than about 2500 Angstroms.

6. The optical coupling structure as in claim 1, further comprising:

a cladding region that is located adjacent to the prism and below the waveguide and the buried oxide layer.

7. The optical coupling structure as in claim 6, wherein the cladding layer is selected from the group consisting of an oxide, a nitride, and air.

8. A method for making an optical coupling structure, the method comprising:

providing a silicon-on-insulator substrate that includes a top side and a bottom side, wherein a buried oxide layer is interposed between the top side and the bottom side;

forming a waveguide on the top side; and

forming a prism on the bottom side, wherein a portion of the buried oxide layer establishes a spacing between the prism and the waveguide.

9. The method as in claim 8, wherein the portion of the buried oxide layer promotes an optical coupling between the prism and the waveguide.

10. The method as in claim 8, wherein the buried oxide layer is less than about 2500 Angstroms.

11. The method as in claim 8, wherein forming the prism on the bottom side comprises bonding the prism to the buried oxide layer.

12. The method as in claim 8, wherein the top side includes a device layer and the bottom side includes a bulk layer.

13. The method as in claim 12, further comprising:

performing a first etch on the bulk layer that determines a location of the prism; and

performing a second etch on the bulk layer that provides a tapered surface of the prism.

14. The method as in claim 13, wherein the first etch forms a cavity that is adjacent to the prism and located below the waveguide.

15. The method as in claim 14, further comprising:

depositing a cladding layer in the cavity.

16. The method as in claim 12, further comprising forming a waveguide in the device layer.

17. A method for operating an optical coupling structure, comprising using a portion of buried oxide layer of a silicon-on-insulator substrate to promote a coupling of light between a bottom side of the silicon-on-insulator substrate and a top side of the silicon-on-insulator substrate.

18. The method as in claim 17, further comprising:

receiving a light beam; and

using the portion of the buried oxide layer to couple light between a prism located on the bottom side to a waveguide located on the top side.

19. The method as in claim 18, further comprising:

using a cavity that is adjacent to the prism and below the waveguide to confine the light to the waveguide.

20. An optical coupling structure, comprising:

a silicon-on-insulator substrate including a top side and a bottom side, wherein a buried oxide layer is interposed between the top side and the bottom side of the silicon-on-insulator substrate; and

a first device located on the bottom side of the silicon-on-insulator substrate, wherein a portion of the buried oxide layer promotes an optical coupling of the first device to at least one device located on the top side of the silicon-on-insulator substrate.

21. The optical coupling structure as in claim 20, further comprising:

a second device located on the top side of the silicon-on-insulator substrate, wherein the second device is configured to receive an electronic signal.

22. The optical coupling structure as in claim 21, wherein the first device is configured to receive an optical signal.