Apparatus for optical coupling and fabrication method thereof

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, the coupling region having a first end and a second end,

wherein a shape of each of the plurality of holes in a top view of the substrate is a polygon with a first central axis and a second central axis perpendicular to and longer than the first central axis, the first central axis and the second central axis of each of the plurality of polygons are either perpendicular to or parallel with a 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 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 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 intervals of the plurality of holes gradually increase from the first end to the second end.

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 a polygon with a first central axis and a second central axis perpendicular to and longer than the first central axis, the first central axis and the second central axis of each of the plurality of polygons are either perpendicular to or parallel with a direction pointing from the first end to the second end.

13. The apparatus for optical coupling as claimed in claim 12 , wherein widths of the plurality of holes gradually increase from the first end to the second end.

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 fabrication method of an apparatus for optical coupling, comprising:

forming a core layer on a substrate, the core layer comprising a plurality of holes located in an optical coupling region of the apparatus for optical coupling, the coupling region having a first end and a second end,

wherein a shape of each of the plurality of holes in a top view of the substrate is a polygon with a first central axis and a second central axis perpendicular to and longer than the first central axis, the first central axis and the second central axis of each of the plurality of polygons are either perpendicular to or parallel with a 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 fabrication method of the apparatus for optical coupling as claimed in claim 16 , wherein the plurality of holes are formed through an etching step.

18. The fabrication method of the apparatus for optical coupling as claimed in claim 16 , wherein the plurality of holes are arranged along a plurality of straight virtual lines extending from the first end to the second end.

19. The fabrication method of the apparatus for optical coupling as claimed in claim 18 , wherein the plurality of straight virtual lines are parallel to each other.

20. The fabrication method of the apparatus for optical coupling as claimed in claim 18 , wherein the plurality of straight virtual lines intersect each other.