Single mode reflector using a nanobeam cavity

Patent metadata

Field	Value
Publication number	US-9647424-B2
Application number	US-201514881741-A
Country	US
Kind code	B2
Filing date	Oct 13, 2015
Priority date	Oct 13, 2015
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

An integrated circuit includes an optical reflector with one or two bus optical waveguides and a one-dimensional, photonic crystal nanobeam cavity to provide single-mode reflection with a narrow bandwidth. In particular, the nanobeam cavity may be implemented on a nanobeam-cavity optical waveguide (such as a channel or ridge optical waveguide), which is optically coupled to the one or two bus optical waveguides. The nanobeam-cavity optical waveguide may include notches along a symmetry axis of the nanobeam-cavity optical waveguide that are partially etched from edges of the nanobeam-cavity optical waveguide toward a center of the nanobeam-cavity optical waveguide. Furthermore, a fill factor of the notches may vary as a function of location along the symmetry axis, while a pitch of the notches is unchanged, to define the nanobeam cavity.

First claim

What is claimed is:

1. An integrated circuit, comprising:
a substrate;
a buried-oxide (BOX) layer disposed on the substrate; and
a semiconductor layer disposed on the BOX layer, wherein the semiconductor layer includes an optical reflector, and wherein the optical reflector includes:
a first bus optical waveguide; and
a nanobeam-cavity optical waveguide optically coupled to the first bus optical waveguide, wherein the nanobeam-cavity optical waveguide includes notches along a symmetry axis of the nanobeam-cavity optical waveguide that are partially etched from edges of the nanobeam-cavity optical waveguide toward a center of the nanobeam-cavity optical waveguide; and
wherein a fill factor of the notches varies as a function of location along the symmetry axis, while a pitch of the notches is unchanged, to define a nanobeam cavity.

2. The integrated circuit of claim 1 , wherein the nanobeam-cavity optical waveguide includes one of: a ridge optical waveguide, and a channel optical waveguide.

3. The integrated circuit of claim 1 , wherein the first bus optical waveguide is curved.

4. The integrated circuit of claim 1 , wherein tapering of the nanobeam-cavity optical waveguide associated with variation of the fill factor along the symmetry axis is adiabatic.

5. The integrated circuit of claim 1 , wherein the fill factor at a midpoint of the nanobeam-cavity optical waveguide is greater than fill factors at locations distal from the midpoint in either direction along the symmetry axis.

6. The integrated circuit of claim 1 , wherein fill factors at locations along the symmetry axis that are symmetric about the midpoint are approximately equal.

7. The integrated circuit of claim 1 , wherein the optical reflector is structured to reflect a wavelength.

8. The integrated circuit of claim 1 , wherein the nanobeam-cavity optical waveguide includes less than a predefined number of notches and the optical reflector has a Q factor greater than a predefined value.

9. The integrated circuit of claim 1 , wherein the optical reflector includes a second bus optical waveguide that is optically coupled to the nanobeam-cavity optical waveguide.

10. The integrated circuit of claim 9 , wherein the optical coupling between the nanobeam-cavity optical waveguide and the first bus optical waveguide is different than the optical coupling between the nanobeam-cavity optical waveguide and the second bus optical waveguide.

11. The integrated circuit of claim 1 , further comprising an external cavity laser, wherein the optical reflector is a reflector at one end of the external cavity laser and, in part, defines an optical cavity in the external cavity laser.

12. A system, comprising:
a processor;
a memory, coupled to the processor, that stores a program module, which, during operation, is executed by the processor; and
an integrated circuit, wherein the integrated circuit includes:
a substrate;
a buried-oxide (BOX) layer disposed on the substrate; and
a semiconductor layer disposed on the BOX layer, wherein the semiconductor layer includes an optical reflector, and wherein the optical reflector includes:
a first bus optical waveguide; and
a nanobeam-cavity optical waveguide optically coupled to the first bus optical waveguide, wherein the nanobeam-cavity optical waveguide includes notches along a symmetry axis of the nanobeam-cavity optical waveguide that are partially etched from edges of the nanobeam-cavity optical waveguide toward a center of the nanobeam-cavity optical waveguide; and
wherein a fill factor of the notches varies as a function of location along the symmetry axis, while a pitch of the notches is unchanged, to define a nanobeam cavity.

13. The system of claim 12 , wherein the nanobeam-cavity optical waveguide includes one of: a ridge optical waveguide, and a channel optical waveguide.

14. The system of claim 12 , wherein the first bus optical waveguide is curved.

15. The system of claim 12 , wherein tapering of the nanobeam-cavity optical waveguide associated with variation of the fill factor along the symmetry axis is adiabatic.

16. The system of claim 12 , wherein the fill factor at a midpoint of the nanobeam-cavity optical waveguide is greater than fill factors at locations distal from the midpoint in either direction along the symmetry axis; and
wherein the fill factors at locations along the symmetry axis that are symmetric about the midpoint are approximately equal.

17. The system of claim 12 , wherein the optical reflector includes a second bus optical waveguide that is optically coupled to the nanobeam-cavity optical waveguide.

18. The system of claim 17 , wherein the optical coupling between the nanobeam-cavity optical waveguide and the first bus optical waveguide is different than the optical coupling between the nanobeam-cavity optical waveguide and the second bus optical waveguide.

19. The system of claim 12 , further comprising an external cavity laser, wherein the optical reflector is a reflector at one end of the external cavity laser and, in part, defines an optical cavity in the external cavity laser.

20. A method for reflecting a wavelength in an output optical signal, wherein the method comprises:
conveying an input optical signal having multiple wavelengths in a bus optical waveguide defined in a semiconductor layer, wherein the semiconductor layer is disposed on a buried-oxide (BOX) layer and the BOX layer is disposed on a substrate;
optically coupling the input optical signal to a nanobeam-cavity optical waveguide, wherein the nanobeam-cavity optical waveguide includes notches along a symmetry axis of the nanobeam-cavity optical waveguide that are partially etched from edges of the nanobeam-cavity optical waveguide toward a center of the nanobeam-cavity optical waveguide; and
wherein a fill factor of the notches varies as a function of location along the symmetry axis, while a pitch of the notches is unchanged, to define a nanobeam cavity; and
reflecting the wavelength in the output optical signal using the nanobeam-cavity optical waveguide.

Assignees

• Oracle Int Corp

Inventors

• Lin Shiyun
• Zheng Xuezhe
• Luo Ying
• Krishnamoorthy Ashok V

Classifications

• G02B6/12007 Primary

  forming wavelength selective elements, e.g. multiplexer, demultiplexer · CPC title

• H01S5/0268

  Integrated waveguide grating router, e.g. emission of a multi-wavelength laser array is combined by a "dragon router" · CPC title

• G02B2006/12104

  Mirror; Reflectors or the like · CPC title

• G02B6/125

  Bends, branchings or intersections · CPC title

• H01S5/101

  Curved waveguide (H01S5/1243 takes precedence) · CPC title