RADIAL OPTICAL COUPLER

• US 20120224805A1
• Filed: 03/05/2011
• Published: 09/06/2012
• Est. Priority Date: 03/05/2011
• Status: Active Grant

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Doerr, Christopher
• Granted Patent: US 9,162,404 B2
• Time in Patent Office: Days
• US Class Current: 385/24
• CPC Class Codes: B29D 11/00663 Production of light guides
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/30 for use between fibre and thin-film device
• CPC Class Codes: G11B 7/1353 Diffractive elements, e.g. holograms or gratings diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44
• CPC Class Codes: G11B 7/1374 Objective lenses optical objectives per se G02B9/00

Abstract

An optical device includes an optical grating coupler and a plurality of optical waveguides coupled thereto. The optical grating coupler is formed along a planar surface of a substrate, and includes a pattern formed by ridges concentrically located on the surface about a center thereon. Each adjacent pair of ridges is separated by a groove. Each waveguide of the plurality of waveguides is oriented about radially with respect to the center, and has a first end that terminates near an outermost one of the ridges. The first ends are about uniformly spaced along the outermost one of the ridges.

Claims

1. An optical device, comprising:

an optical grating coupler formed along a planar surface of a substrate, said grating coupler including a pattern formed by ridges concentrically located on the surface about a center thereon, with each adjacent pair of ridges being separated by a groove; and

a plurality of optical waveguides having first ends that terminate near an outermost one of the ridges, the first ends being about uniformly spaced along said outermost one of the ridges and being oriented radially with respect to the center.

2. The optical device of claim 1, further comprising a plurality of optical transition portions, each transition portion partially filling a region between adjacent ones of the first ends of the waveguides.

3. The optical device of claim 2, wherein said transition portion includes a first subportion having first thickness and a second subportion having a second thickness.

4. The optical device of claim 1, wherein said plurality is configured to deliver a corresponding plurality of optical signals to said outermost one of the ridges, with a phase angle of said corresponding plurality of optical signals advancing by a nonzero integer multiple of 2π

around said outermost ridge.

5. The optical device of claim 1, wherein said pattern of ridges is radially chirped with respect to the center.

6. The optical device of claim 1, wherein said plurality of radial waveguides is configured to deliver a corresponding plurality of optical signals to said outermost one of the ridges with a substantially equal phase.

7. The optical device of claim 1, further comprising a star coupler having a number of output or input ports equal to a number of said plurality of radial waveguides, each of the output or input ports being connected to a corresponding one of said radial waveguides.

8. The optical device of claim 7, further comprising a plurality of polarization beam splitters, each polarization beam splitter being coupled to a corresponding port of said star coupler.

9. The optical device of claim 8, further comprising a plurality of optical signal sources, each of said polarization beam splitters being connected to two of said optical signal sources, one of said two being configured to produce TE mode light and the other of the two being configured to produce TM mode light.

10. The optical device of claim 1, further comprising a ring-core multimode optical fiber having an end located over and facing said circular grating coupler.

11. The optical device of claim 10, wherein said outermost ridge has a diameter about equal to an outer diameter of said ring-core.

12. A method, comprising:

forming a grating coupler of an optical medium along a planar surface of a substrate, said grating including a plurality of ridges concentrically located about a center on the surface, with each pair of adjacent ridges being separated by a groove; and

forming a plurality of optical waveguides having first ends that terminate near an outermost one of the ridges, the first ends being about uniformly spaced along said outermost one of the ridges and being oriented radially with respect to the center.

13. The method of claim 12, further comprising forming an optical transition portion of said medium that partially fills a region between adjacent first ends of the waveguides.

14. The method of claim 13, wherein said transition portion includes a first subportion having first thickness and a second subportion having a second thickness.

15. The method of claim 12, wherein said plurality is configured to deliver a corresponding plurality of optical signals to said outermost ridge, with a phase of said corresponding plurality advancing by a nonzero integer multiple of 2π

around said outermost ridge.

16. The method of claim 12, wherein said grating is radially chirped with respect to the center.

17. The method of claim 12, wherein said plurality of waveguides is configured to deliver a corresponding plurality of optical signals to said outermost ridge with a substantially equal phase.

18. The method of claim 12, further comprising forming a star coupler along said surface of the substrate having a number of output or input ports equal to a number of said plurality of radial waveguides, the forming connecting each output or input port to a corresponding one of said radial waveguides.

19. The method of claim 18, further comprising providing a plurality of polarization beam splitters, each polarization beam splitter being connected to a corresponding port of said star coupler.

20. The method of claim 19, further comprising coupling said plurality of polarization beam splitters to a corresponding plurality of optical sources such that each of said polarization beam splitters is connected to two of said optical signal sources, a first of the two of said optical signal sources being configured to produce TM mode and a second of the two of said optical signal sources being configured to produce TE mode light.