Optical amplifier including multi-section gain waveguide

• US 9,685,763 B1
• Filed: 07/26/2016
• Issued: 06/20/2017
• Est. Priority Date: 02/05/2014
• Status: Active Grant

• Current Assignee: Openlight Photonics Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Koch, Brian R., Fish, Gregory Alan, Norberg, Erik
• Primary Examiner(s): Torres, Juan A
• Application Number:
  US15/219,515
• Time in Patent Office: 329 Days
• Field of Search: 398 79
• CPC Class Codes: H01S 5/021 Silicon based substrates
• CPC Class Codes: H01S 5/026 Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers stabilisation of output H01S5/06
• CPC Class Codes: H01S 5/1014 Tapered waveguide, e.g. spotsize converter H01S5/1064 takes precedence
• CPC Class Codes: H01S 5/1028 Coupling to elements in the cavity, e.g. coupling to waveguides adjacent the active region, e.g. forward coupled [DFC] structures
• CPC Class Codes: H01S 5/1032 Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
• CPC Class Codes: H01S 5/50 Amplifier structures not provided for in groups H01S5/02 - H01S5/30
• CPC Class Codes: H01S 5/5027 Concatenated amplifiers, i.e. amplifiers in series or cascaded
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 10/66 Non-coherent receivers, e.g. using direct detection
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

Described herein are methods, systems, and apparatuses to utilize a semiconductor optical amplifier (SOA) comprising a silicon layer including a silicon waveguide, a non-silicon layer disposed on the silicon layer and including a non-silicon waveguide, first and second mode transition region comprising tapers in the silicon waveguide and/or the non-silicon waveguide for exchanging light between the waveguide, and a plurality of regions disposed between the first and second mode transition regions comprising different cross-sectional areas of the silicon waveguide and the non-silicon waveguide such that confinement factors for the non-silicon waveguide in each of the plurality of regions differ.

Claims

1. An optical amplifier, comprising:

a silicon layer shaped to form a silicon waveguide;

a gain layer positioned on the silicon layer and shaped to form a gain waveguide,

the gain waveguide configured to;

receive light from the silicon waveguide at a first tapered transition,

amplify the received light, and

direct the amplified light into the silicon waveguide at a second tapered transition;

the gain waveguide shaped to include;

a first section between the first tapered transition and the second tapered transition, the first section having a first constant cross-sectional size along its length;

a second section between the first tapered transition and the second tapered transition, the second section having a second constant cross-sectional size along its length, the second constant cross-sectional size differing from the first constant cross-sectional size; and

a tapered section between the first and second sections, along which the cross-sectional size continuously varies from the first constant cross-sectional size to the second constant cross-sectional size; and

at least one electrode configured to apply current through gain material in the gain waveguide.

2. The optical amplifier of claim 1, wherein the gain waveguide shapes light traveling in the gain waveguide to have a first mode size in the first section and a second mode size in the second section, the second mode size differing from the first mode size.

3. The optical amplifier of claim 1,

wherein a confinement factor represents a fraction of mode energy density confined in a core of the gain waveguide;

and

wherein a confinement factor of the second section differs from a confinement factor of the first section.

4. The optical amplifier of claim 1, wherein at least one of the silicon waveguide or the gain waveguide vary in cross-sectional size at the first tapered transition.

5. The optical amplifier of claim 1, wherein at least one of the silicon waveguide or the gain waveguide vary in cross-sectional size at the second tapered transition.

6. The optical amplifier of claim 1, wherein the at least one electrode includes a single electrode extending along the first and second sections of the gain waveguide.

7. The optical amplifier of claim 1, wherein the at least one electrode includes a first electrode positioned proximate the first section of the gain waveguide, and a second electrode positioned proximate the second section of the gain waveguide.

8. The optical amplifier of claim 1, wherein the gain waveguide shaped to further include:

a third section between the first tapered transition and the second tapered transition such that the second section is between the first and third sections, the third section having a third constant cross-sectional size along its length, the third constant cross-sectional size differing from the second constant cross-sectional size; and

a second tapered section between the second and third sections, along which the cross-sectional size continuously varies from the second constant cross-sectional size to the third constant cross-sectional size.

9. The optical amplifier of claim 4, wherein the gain waveguide continuously increases in cross-sectional size from a first end of the gain waveguide through the first tapered transition.

10. The optical amplifier of claim 5, wherein the gain waveguide continuously increases in cross-sectional size from a second end of the gain waveguide through the second tapered transition.

11. The optical amplifier of claim 7, further comprising an electrical isolation region positioned to electrically isolate the first electrode from the second electrode.

12. The optical amplifier of claim 8, wherein the third constant cross-sectional size is greater than the second constant cross-sectional size, and the second constant cross-sectional size is greater than the first constant cross-sectional size.

13. The optical amplifier of claim 8, wherein the third constant cross-sectional size is less than the second constant cross-sectional size, and the second constant cross-sectional size is less than the first constant cross-sectional size.

14. A method for amplifying light, the method comprising:

providing light in a silicon waveguide;

coupling the light from the silicon waveguide to a gain waveguide;

applying an electrical current to gain material in a first section of the gain waveguide to amplify the light in the first section of the gain waveguide, the first section having a first constant cross-sectional size along its length;

applying an electrical current to gain material in a second section of the gain waveguide to further amplify the light in the second section of the gain waveguide, the second section having a second constant cross-sectional size along its length, the second constant cross-sectional size differing from the first constant cross-sectional size; and

coupling the amplified light from the gain waveguide to the silicon waveguide.

15. The method of claim 14, further comprising:

applying the electrical current to the first section with a first electrode; and

applying the electrical current to the second section with a second electrode electrically isolated from the first electrode.

16. An optical amplifier, comprising:

a silicon layer shaped to form a silicon waveguide;

a gain layer positioned on the silicon layer and shaped to form a gain waveguide,

the gain waveguide configured to;

receive light from the silicon waveguide at a first tapered end,

amplify the received light, and

direct the amplified light into the silicon waveguide at a second tapered end;

the gain waveguide shaped to include a plurality of sections between the first and second tapered ends, each section having a constant cross-sectional size along its length, the sections increasing in cross-sectional sizes from the first tapered end to the second tapered end, each section separated from an adjacent section by a tapered portion in the gain waveguide; and

a plurality of electrodes configured to apply current through gain material in the gain waveguide, each electrode of the plurality of electrodes being positioned proximate a respective section of the plurality of sections.

17. The optical amplifier of claim 16, further comprising at least one electrical isolation region positioned to electrically isolate the plurality of electrodes from one another.

18. The optical amplifier of claim 16, wherein the gain waveguide shapes light traveling in the gain waveguide to have a respective mode sizes in the respective sections, at least two of the mode sizes differing from one another.

19. The optical amplifier of claim 16,

wherein a confinement factor represents a fraction of mode energy density confined in a core of the gain waveguide;

and

wherein a confinement factor of a first section of the plurality of sections differs from a confinement factor of a second section of the plurality of sections.