Low-loss waveguide transition

Patent metadata

Field	Value
Publication number	US-2016011371-A1
Application number	US-201514796552-A
Country	US
Kind code	A1
Filing date	Jul 10, 2015
Priority date	Jul 11, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

A waveguide device that includes a first waveguide, a second waveguide and a transition region. The first waveguide has a first height and the second waveguide has a second height different from the first height. The transition region is between the first waveguide and the second waveguide and includes an asymmetrical taper of the first waveguide.

First claim

What is claimed is:

1 . A waveguide device comprising:
a first waveguide with a first height; a second waveguide with a second height different from the first height; a transition region between the first waveguide and the second waveguide, the transition region comprising an asymmetrical taper of the first waveguide.

2 . The waveguide device of claim 1 , wherein the first height and the second height is along a first direction, and the asymmetrical taper is asymmetric about an imaginary plane that bisects a width of the first waveguide, wherein the width of the first waveguide is along a second direction perpendicular to the first direction.

3 . The waveguide device of claim 1 , wherein the asymmetrical taper begins at a first side of the first waveguide, but not a second side of the first waveguide, wherein the first side and the second side are opposing sides of the first waveguide.

4 . The waveguide device of claim 1 , wherein the transition region comprises a transition tip with a width less than 50 nm.

5 . The waveguide device of claim 1 , wherein the second waveguide has a first width at the transition region and a second width a first distance from the transition region, wherein the first width is greater than the second width.

6 . The waveguide device of claim 1 , wherein the second waveguide includes a tapered region.

7 . The waveguide device of claim 6 , wherein the tapered region of the second waveguide begins at the transition region.

8 . The waveguide device of claim 6 , wherein the tapered region of the second waveguide is a symmetric taper.

9 . The waveguide device of claim 6 , wherein the tapered region of the second waveguide is an asymmetric taper.

10 . The waveguide device of claim 1 , wherein the first waveguide has a transverse width that supports only the propagation of a single mode in each polarization at an operational wavelength.

11 . The waveguide device of claim 1 , wherein the first waveguide is formed from silicon.

12 . The waveguide device of claim 1 , wherein the waveguide device is monolithic.

13 . A method comprising:
receiving light within a first waveguide of a photonic chip, wherein the first waveguide has a first height; transitioning the light from the first waveguide to a second waveguide of the photonic chip using an asymmetrical taper of the first waveguide, wherein the first waveguide has a second height different from the first height.

14 . The method of claim 13 , wherein the first height and the second height is along a first direction, and the asymmetrical taper is asymmetric about an imaginary plane that bisects a width of the first waveguide, wherein the width of the first waveguide is along a second direction perpendicular to the first direction.

15 . The method of claim 13 , wherein the asymmetrical taper begins at a first side of the first waveguide, but not a second side of the first waveguide, wherein the first side and the second side are opposing sides of the first waveguide.

16 . The method of claim 13 , further comprising:
changing a transverse mode size of the light as it propagates through the second waveguide.

17 . The method of claim 16 , wherein changing a transverse mode size of the light comprises tapering the width of the second waveguide.

18 . The method of claim 13 , further comprising:
outputting the light from the second waveguide; and receiving the light at an optical fiber.

19 . A method of fabricating a waveguide device comprising a first waveguide formed from a guiding material with a first width, the method comprising:
forming a first mask over a guiding material layer of a first depth, wherein the first mask leaves a portion of the guiding material layer exposed, wherein the exposed portion of the guiding material layer has a second width greater than the first width and is asymmetric with respect to an imaginary plane that bisects the width of the first waveguide; partially removing the exposed portion of the guiding material layer down to a second depth that is less than the first depth; removing the first mask; forming a second mask over the guiding material layer, wherein the second mask is a rectangle with a width equal to the first width; removing the guiding material layer that is not protected by the second mask; and removing the second mask.

20 . The method of claim 19 , wherein the second mask is a hard mask and forming the second mask comprises:
depositing a hard mask material over the guiding material layer; depositing a soft mask over the hard mask material wherein the soft mask is a rectangle with a width equal to the first width; and removing the hard mask material that is not protected by the soft mask.

Assignees

• Acacia Communications Inc

Inventors

• Vermeulen Diedrik

Classifications

• G02B6/136

  by etching · CPC title

• G02B6/126

  using polarisation effects {(G02B6/1226 takes precedence)} · CPC title

• G02B6/305

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

• G02B2006/12061

  Silicon · CPC title

• G02B6/1228 Primary

  Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305) · CPC title