Photonics chips including a photonic coupler and a photodetector
Structures for a photonics chip that include a photodetector and methods of forming such structures. The structure comprises a photodetector, a first waveguide core coupled to the photodetector, and a second waveguide core coupled to the photodetector. The structure further comprises a third waveguide core including a section disposed laterally between a section of the first waveguide core and a section of the second waveguide core.
1 . A structure for a photonics chip, the structure comprising:
a photodetector;
a first waveguide core coupled to the photodetector, the first waveguide core including a first section;
a second waveguide core coupled to the photodetector, the second waveguide core including a first section; and
a third waveguide core including a section disposed laterally between the first section of the first waveguide core and the first section of the second waveguide core,
wherein the photodetector includes a semiconductor layer configured to absorb light of a given wavelength, the first waveguide core includes a second section adjacent to the semiconductor layer of the photodetector, and the second waveguide core includes a second section adjacent to the semiconductor layer of the photodetector.
2 . The structure of claim 1 wherein the semiconductor layer of the photodetector is disposed laterally between the second section of the first waveguide core and the second section of the second waveguide core.
3 . The structure of claim 1 wherein the first section of the first waveguide core, the first section of the second waveguide core, and the first section of the third waveguide core are included in a photonic coupler, the photonic coupler is configured to split light with transverse electric polarization with a splitting ratio between the first section of the first waveguide core and the first section of the second waveguide core, and the photonic coupler is configured to split light with transverse magnetic polarization with the splitting ratio between the first section of the first waveguide core and the first section of the second waveguide core.
4 . The structure of claim 1 wherein the first section of the first waveguide core is tapered and terminates at a first end, the first section of the second waveguide core is tapered and terminates at a second end, the first section of the third waveguide core is tapered and terminates at a third end, the first section of the third waveguide core is tapered in an opposite direction from the first section of the first waveguide core, and the first section of the third waveguide core is tapered in an opposite direction from the first section of the second waveguide core.
5 . The structure of claim 4 wherein the first section of the first waveguide core is spaced from the first section of the third waveguide core by a first gap, and the first section of the first waveguide core is spaced from the first section of the third waveguide core by a second gap.
6 . The structure of claim 1 wherein the first waveguide core comprises silicon, the third waveguide core comprises silicon, and the third waveguide core comprises silicon.
7 . The structure of claim 1 wherein the first waveguide core comprises silicon, the third waveguide core comprises silicon, and the third waveguide core comprises silicon nitride.
8 . The structure of claim 1 wherein the semiconductor layer comprises germanium.
9 . The structure of claim 1 wherein the semiconductor layer comprises a III-V compound semiconductor material.
10 . The structure of claim 1 wherein the semiconductor layer comprises silicon.
11 . The structure of claim 1 further comprising:
a fourth waveguide core including a section that overlaps with the first section of the first waveguide core; and
a fifth waveguide core including a section that overlaps with the first section of the second waveguide core.
12 . The structure of claim 11 wherein the fourth waveguide core and the fifth waveguide core comprise polysilicon or amorphous silicon.
13 . The structure of claim 12 wherein the first waveguide core comprises silicon, the fourth waveguide core comprises silicon, and the fourth waveguide core comprises silicon.
14 . The structure of claim 11 wherein the fourth waveguide core and the fifth waveguide core comprise silicon nitride.
15 . The structure of claim 14 wherein the first waveguide core comprises silicon, the fourth waveguide core comprises silicon, and the fourth waveguide core comprises silicon.
16 . The structure of claim 11 wherein the first section of the first waveguide core is tapered, and the section of the fourth waveguide core is tapered.
17 . The structure of claim 11 wherein the first section of the second waveguide core is tapered, and the section of the fifth waveguide core is tapered.
18 . The structure of claim 1 further comprising:
a fourth waveguide core that overlaps with the first section of the first waveguide core; and
a fifth waveguide core that overlaps with the first section of the second waveguide core.
19 . The structure of claim 18 wherein the fourth waveguide core and the fifth waveguide core comprise polysilicon, amorphous silicon, or silicon nitride.
20 . A method of forming a structure for a photonics chip, the method comprising:
forming a photodetector;
forming a first waveguide core coupled to the photodetector;
forming a second waveguide core coupled to the photodetector; and
forming a third waveguide core including a section disposed laterally between a first section of the first waveguide core and a first section of the second waveguide core,
wherein the photodetector includes a semiconductor layer configured to absorb light of a given wavelength, the first waveguide core includes a second section adjacent to the semiconductor layer of the photodetector, and the second waveguide core includes a second section adjacent to the semiconductor layer of the photodetector.