SYSTEM AND METHOD FOR OPTICAL COUPLING
A system and method for optical coupling. In some embodiments, the system includes a first semiconductor chip, including a semiconductor optical amplifier; and a second semiconductor chip, including a fork coupler. The fork coupler may includes a plurality of waveguide fingers, and an output waveguide. The waveguide fingers may be configured to guide, together, a first optical mode of the fork coupler; and the fork coupler may be arranged such that an output mode of the semiconductor optical amplifier couples to the first optical mode of the fork coupler.
1 . A system, comprising:
a first semiconductor chip, comprising a semiconductor optical amplifier; and
a second semiconductor chip, comprising a fork coupler,
wherein:
the fork coupler comprises:
a plurality of waveguide fingers, and
an output waveguide;
the waveguide fingers are configured to guide, together, a first optical mode of the fork coupler; and
the fork coupler is arranged such that an output mode of the semiconductor optical amplifier couples to the first optical mode of the fork coupler.
2 . The system of claim 1 , wherein the first semiconductor chip is a III-V semiconductor chip.
3 . The system of claim 1 , wherein the second semiconductor chip is a silicon nitride semiconductor chip.
4 . The system of claim 1 , wherein the first optical mode has a width between 1000 nm and 3000 nm.
5 . The system of claim 1 , wherein the system is configured to operate over a range of wavelengths, the range including a first wavelength, the first wavelength being greater than 200 nm and less than 1065 nm.
6 . The system of claim 1 , wherein the fork coupler includes 4 waveguide fingers.
7 . The system of claim 6 , wherein the fork coupler includes 5 waveguide fingers.
8 . The system of claim 1 , wherein the fork coupler does not include 8 waveguide fingers.
9 . The system of claim 1 , wherein:
an edge of the first semiconductor chip is separated from an edge of the second semiconductor chip by a gap; and
a waveguide finger of the plurality of waveguide fingers is oblique to the gap.
10 . The system of claim 9 , wherein an angle between a waveguide finger of the plurality of waveguide fingers and a direction perpendicular to the gap is between 3 degrees and 25 degrees.
11 . The system of claim 9 , further comprising an index-matching material in the gap.
12 . The system of claim 9 , wherein:
the edge of the second semiconductor chip is an edge of a cavity in the second semiconductor chip, and
the first semiconductor chip is in the cavity.
13 . The system of claim 1 , wherein the fork coupler further comprises a waveguide-end bar; and
each of the plurality of waveguide fingers extends to the waveguide-end bar.
14 . The system of claim 1 , further comprising a combiner between the output waveguide and the plurality of waveguide fingers.
15 . The system of claim 14 , wherein the combiner is a composite Y-coupler.
16 . The system of claim 14 , further comprising a waveguide section having a waist, between the output waveguide and the combiner.
17 . The system of claim 16 , wherein a width of the waveguide section at the waist is less than ½ of a width of the output waveguide.
18 . The system of claim 1 , wherein the first optical mode has a width at least 1.2 times as wide as a mode of the output waveguide.
19 . The system of claim 18 , wherein the first optical mode has a width at least 1.5 times as wide as a mode of the output waveguide.