Optical amplifier including multi-section gain waveguide
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.
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.