Optical coupler comprising vertically offset waveguide cores

Patent metadata

Field	Value
Publication number	US-10677991-B2
Application number	US-201816189087-A
Country	US
Kind code	B2
Filing date	Nov 13, 2018
Priority date	Jun 4, 2015
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

A composite optical waveguide is constructed using an array of waveguide cores, in which one core is tapered to a larger dimension, so that all the cores are used as a composite input port, and the one larger core is used as an output port. In addition, transverse couplers can be fabricated in a similar fashion. The waveguide cores are preferably made of SiN. In some cases, a layer of SiN which is provided as an etch stop is used as at least one of the waveguide cores. The waveguide cores can be spaced away from a semiconductor layer so as to minimize loses.

First claim

What is claimed is:

1. A photonic integrated circuit (PIC) comprising:
a substrate;
an optical device layer supported over the substrate;
a coupler configured for coupling light vertically to or away from the optical device layer, the coupler comprising a vertical coupler and an edge coupler for coupling the light between a side facet of the PIC and the optical device layer, the edge coupler spaced away from the substrate, with the optical device layer and the vertical coupler between the substrate and the edge coupler, thereby reducing loss due to substrate coupling;
the coupler comprising a plurality of waveguide cores vertically offset from the optical device layer and each other, each waveguide core configured for propagating the light in a propagation direction parallel to each other, and configured for coupling the light, sequentially and evanescently, between adjacent vertically offset waveguide cores of the plurality of waveguide cores.

2. The PIC according to claim 1 , wherein the edge coupler includes:
a first waveguide core including a first input end and a narrower first output end;
a second waveguide core including a second input end, substantially a same width as the first input end of the first waveguide, and a wider second output end.

3. The PIC according to claim 2 , wherein the second waveguide core is longer than the first waveguide core.

4. The PIC according to claim 2 , wherein the edge coupler includes:
a third waveguide core laterally offset from the first waveguide core.

5. The PIC according to claim 4 , wherein the third waveguide core including a third input end and a narrower third output end.

6. The PIC according to claim 4 , wherein the edge coupler includes:
a fourth waveguide core laterally offset from the second waveguide core.

7. The PIC according to claim 6 , wherein the fourth waveguide core includes a fourth input end and a narrower fourth output end.

8. The PIC according to claim 4 , wherein the vertical coupler includes one or more additional waveguide cores configured to couple the light in a transverse direction relative to the propagation direction of the edge coupler from the edge coupler to the optical device layer.

9. The PIC according to claim 1 , further comprising a multilevel metallization above the optical device layer including a plurality of stop layers therebetween; wherein each of the plurality of waveguide cores is comprised of a portion of one of the stop layers.

10. The PIC according to claim 9 , wherein each stop layer comprises a dielectric material enabling illumination of a desired wavelength.

11. The PIC according to claim 10 , wherein the dielectric material is selected from the group consisting of silicon nitride, silicon oxynitride, silicon dioxide, doped silicon dioxide.

12. The PIC according to claim 1 , wherein the optical device layer includes a laser for generating the light for output the coupler to a second waveguide.

13. The PIC according to claim 1 , wherein the optical device layer includes a photodetector for receiving light from a second waveguide via the coupler.

14. The PIC according to claim 4 , wherein the first waveguide core, the second waveguide core and the third waveguide core comprise a composite waveguide configured for converting a mode size of the light between less than 1 μm and greater than 5 μm.

15. The PIC according to claim 4 , wherein a first end of each of the first waveguide core, the second waveguide core and the third waveguide core includes a width of less than 1 micron and a thickness of less than 1 micron.

16. The PIC according to claim 1 , wherein each of the plurality of waveguide cores includes a thickness of about 120 nm.

17. The PIC according to claim 2 , wherein the second waveguide core includes a width that expands from about 300 nm at the second input end to about 1 μm at the second output end.

18. A method of manufacturing a photonic integrated circuit (PIC) comprising:
providing an optical device layer including a first waveguide on a substrate;
depositing a first stop layer above the optical device layer;
depositing a first metal layer on the first stop layer;
depositing a second stop layer on the first metal layer;
depositing a second metal layer on the second stop layer;
depositing a third stop layer on the second metal layer; and
patterning the first, second and third stop layers into a plurality of waveguide cores forming a coupler for vertically coupling light away from the optical device layer, thereby reducing loss due to substrate coupling; the coupler comprising the plurality of waveguide cores vertically offset from the optical device layer and each other, each of the plurality of waveguide cores configured for propagating the light in a propagation direction parallel to each other, and configured for coupling the light sequentially and evanescently between adjacent vertically offset waveguide cores of the plurality of waveguide cores.

19. The method according to claim 18 , wherein the coupler includes:
a first waveguide core including a first input end and a narrower first output end;
a second waveguide core including a second input end, substantially a same width as the first input end of the first waveguide, and a wider second output end.

Assignees

• Elenion Tech Llc

Inventors

• Novack Ari
• Shi Ruizhi
• Hochberg Michael J
• Baehr-Jones Thomas

Classifications

• G02B6/2821

  using lateral coupling between contiguous fibres to split or combine optical signals · CPC title

• G02B6/305 Primary

  and having an integrated mode-size expanding section, e.g. tapered waveguide · CPC title

• G02B2006/12121

  Laser · CPC title

• G02B6/1223

  high refractive index type, i.e. high-contrast waveguides · CPC title

• G02B6/136

  by etching · CPC title