Apparatus for optical coupling and system for communication

1. An apparatus for optical coupling, having an optical coupling region and comprising:

a substrate; and

a core layer disposed on the substrate and comprising a plurality of holes located in the optical coupling region,

wherein an effective refractive index of the core layer gradually decreases from a first end of the optical coupling region to a second end of the optical coupling region,

wherein a shape of each of the plurality of holes in a top view of the substrate is an octagon with a first central axis and a second central axis perpendicular to and longer than the first central axis, the second central axis of each of the plurality of octagons located near the first end is perpendicular to a direction pointing from the first end to the second end, and the second central axis of each of the plurality of octagons located near the second end is parallel to the direction pointing from the first end to the second end, and

wherein in a cross-section plane perpendicular to the substrate and passing through both the first end and the second end, widths and intervals of the plurality of holes gradually increase from the first end to the second end.

2. The apparatus for optical coupling as claimed in claim 1 , wherein the plurality of holes have the same depth.

3. The apparatus for optical coupling as claimed in claim 1 , wherein a material of the substrate comprises silicon oxide, and a material of the core layer comprises silicon.

4. The apparatus for optical coupling as claimed in claim 1 , wherein a maximum thickness of the core layer is larger than or equal to 250 nm and smaller than or equal to 350 nm.

5. The apparatus for optical coupling as claimed in claim 1 , wherein a maximum depth of each of the plurality of holes is larger than or equal to 70 nm and smaller than or equal to 270 nm.

6. The apparatus for optical coupling as claimed in claim 1 , wherein the widths of the plurality of holes are larger than or equal to 100 nm and smaller than or equal to 1000 nm.

7. The apparatus for optical coupling as claimed in claim 1 , wherein the intervals of the plurality of holes are larger than or equal to 200 nm and smaller than or equal to 500 nm.

8. The apparatus for optical coupling as claimed in claim 1 , wherein pitches of the plurality of holes are larger than or equal to 300 nm and smaller than or equal to 800 nm.

9. The apparatus for optical coupling as claimed in claim 1 , further comprising:

a cladding layer disposed on the core layer and filled in the plurality of holes.

10. The apparatus for optical coupling as claimed in claim 1 , wherein the core layer has two output portions spaced apart from each other and located on the second end of the optical coupling region, and

wherein the plurality of holes are configured in a quadrilateral array having two convex sides adjacent to the first end of the optical coupling region and two concave sides adjacent to the second end of the optical coupling region.

11. The apparatus for optical coupling as claimed in claim 1 , wherein the core layer has a fan-shaped or rectangular-shaped portion located in the optical coupling region, and

wherein the plurality of holes are configured in a fan-shaped or rectangular-shaped array.

12. An apparatus for optical coupling, having an optical coupling region and comprising:

a substrate; and

a core layer disposed on the substrate and comprising a plurality of holes located in the optical coupling region,

wherein the plurality of holes are arranged along a plurality of lines extending from a first end of the optical coupling region to a second end of the optical coupling region,

wherein in a cross-section plane perpendicular to the substrate and passing through both the first end and the second end, widths and intervals of the holes increase from the first end to the second end, and

wherein a shape of each of the plurality of holes in a top view of the substrate is an octagon with a first central axis and a second central axis perpendicular to and longer than the first central axis, the second central axis of each of the plurality of octagons located near the first end is perpendicular to a direction pointing from the first end to the second end, and the second central axis of each of the plurality of octagons located near the second end is parallel to the direction pointing from the first end to the second end.

13. The apparatus for optical coupling as claimed in claim 12 , wherein the plurality of lines are virtual lines having different curvatures.

14. The apparatus for optical coupling as claimed in claim 12 , wherein the plurality of lines are straight virtual lines parallel to each other.

15. The apparatus for optical coupling as claimed in claim 12 , wherein the plurality of lines are straight virtual lines intersecting each other.

16. A system for communication, comprising:

a semiconductor photonic die on a substrate, wherein the semiconductor photonic die comprises at least one trench;

an optical fiber array attached to the semiconductor photonic die; and

at least one grating coupler in the at least one trench for transmitting optical signals between the semiconductor photonic die and the optical fiber array, and the at least one grating coupler comprising:

a core layer comprising a plurality of holes located in an optical coupling region of the grating coupler, wherein:

an effective refractive index of the core layer gradually decreases from a first end of the optical coupling region to a second end of the optical coupling region, and

a non-zero angle is formed between an axis of the optical fiber array and a direction perpendicular to the substrate, wherein a shape of each of the plurality of holes in a top view of the substrate is an octagon with a first central axis and a second central axis perpendicular to and longer than the first central axis, the second central axis of each of the plurality of octagons located near the first end is perpendicular to a direction pointing from the first end to the second end, and the second central axis of each of the plurality of octagons located near the second end is parallel to the direction pointing from the first end to the second end, and

wherein in a cross-section plane perpendicular to the substrate and passing through both the first end and the second end, widths and intervals of the plurality of holes gradually increase from the first end to the second end.

17. The system for communication as claimed in claim 16 , wherein the plurality of holes have the same depth.

18. The system for communication as claimed in claim 17 , wherein a maximum depth of each of the plurality of holes is larger than or equal to 70 nm and smaller than or equal to 270 nm.

19. The system for communication as claimed in claim 17 , wherein the intervals of the plurality of holes are larger than or equal to 200 nm and smaller than or equal to 500 nm.

20. The system for communication as claimed in claim 16 , wherein pitches of the plurality of holes are larger than or equal to 300 nm and smaller than or equal to 800 nm.