Thin silicon photonics with integrated III-V waveguide
A device for thin-film silicon photonics with an integrated III-V waveguide structure includes a substrate containing a silicon layer and a III-V waveguide structure bonded to the substrate. The device also includes a waveguide transition structure, enabling light to be coupled between the silicon layer and the III-V waveguide structure. The waveguide transition structure may include a first section, a second section, and a third section, each section including one or more tapered segments.
1 . A device comprising:
a substrate comprising a silicon layer;
a III-V structure bonded to the substrate; and
formed in the silicon layer and the III-V structure, a waveguide transition structure comprising first, second, and third sections along an optical axis, the waveguide transition structure comprising:
a silicon transition segment formed in the silicon layer and extending across the first, second, and third sections, wherein the silicon transition segment increases in width from an eighth width at the interface between the first and second sections to a ninth width at the interface between the second and third sections, the eight width being less than the ninth width; and
a III-V slab transition segment formed in the III-V structure and extending across the first and second sections and into the third section, wherein:
the III-V slab transition segment decreases in width from a first width at an interface between a first exterior edge of the device and the first section to a second width at an interface between the first section and the second section;
the III-V slab transition segment decreases in width from the second width at the interface between the first section and the second section to a third width at an interface between the second section and the third section; and
the III-V slab transition segment decreases in width from the third width at the interface between the second section and the third section to a fourth width at an interface between the third section and a second exterior edge of the device.
2 . The device of claim 1 , wherein the III-V slab transition segment is formed in a slab layer of the III-V structure, the slab layer comprising an optically active III-V material.
3 . The device of claim 1 , wherein the waveguide transition structure further comprises a III-V rib transition segment formed in the III-V structure and extending across the first and second sections, wherein:
the III-V rib transition segment decreases in width from a fifth width at the interface of the first exterior edge of the device and the first section and to a sixth width at the interface of the first section and the second section; and
the III-V rib transition segment decreases in width from the sixth width at the interface between the first section and the second section to a seventh width at the interface between the second section and the third section.
4 . The device of claim 3 , wherein the III-V rib transition segment is formed in a rib layer of the III-V structure, the rib layer comprising a p-type III-V material.
5 . The device of claim 1 , wherein the waveguide transition structure further comprises a silicon transition segment formed in the silicon layer and extending across the first, second, and third sections, wherein:
the silicon transition segment has a constant width of the eighth width within the first section;
and
the silicon transition segment has a constant width of the ninth width within the third section.
6 . The device of claim 1 , further comprising:
an anode, the anode overlapping the III-V slab transition segment in at least the first section; and
a cathode adjacent to the III-V slab transition segment.
7 . The device of claim 1 , further comprising:
a dielectric layer separating the III-V structure from the silicon layer.
8 . The device of claim 7 , wherein the III-V structure comprises a n-type layer, the n-type layer being between the III-V slab transition segment and the dielectric layer.
9 . The device of claim 8 , wherein the dielectric layer is formed of silicon oxide (SiO 2 ), silicon nitride (SiN x ), or aluminum oxide (Al 2 O 3 ).
10 . The device of claim 1 , wherein at least a portion of the third section is free of the III-V structure.
11 . The device of claim 1 , wherein the silicon layer has a thickness between 150 nanometers and 350 nanometers.
12 . A method of manufacturing a photonic device, the method comprising:
providing a substrate comprising a silicon layer;
patterning the silicon layer to form a silicon waveguide transition segment extending across the first, second, and third sections, wherein the silicon transition segment increases in width from an eighth width at the interface between the first and second sections to a ninth width at the interface between the second and third sections, the eight width being less than the ninth width;
forming a top dielectric layer above the silicon layer;
bonding a III-V semiconductor structure to the top dielectric layer; and
patterning the III-V semiconductor structure to form a III-V waveguide transition structure overlapping the silicon waveguide transition segment, the III-V waveguide transition structure comprising a first section, second section, and third section arranged sequentially along an optical axis of the photonic device, the III-V waveguide transition structure comprising a III-V slab transition segment extending across the first and second sections and into the third section, wherein:
the III-V slab transition segment decreases in width from a first width at an interface between a first exterior edge of the device and the first section to a second width at an interface between the first section and the second section;
the III-V slab transition segment decreases in width from the second width at the interface between the first section and the second section to a third width at an interface between the second section and the third section; and
the III-V slab transition segment decreases in width from the third width at the interface between the second section and the third section to a fourth width at an interface between the third section and a second exterior edge of the device.
13 . The method of claim 12 , wherein the III-V slab transition segment is formed in a slab layer of the III-V semiconductor structure, the slab layer comprising an optically active III-V material.
14 . The method of claim 12 , wherein the III-V waveguide transition structure further comprises a III-V rib transition segment extending across the first and second sections, wherein:
the III-V rib transition segment decreases in width from a fifth width at the interface of the first exterior edge of the device and the first section and to a sixth width at the interface of the first section and the second section; and
the III-V rib transition segment decreases in width from the sixth width at the interface between the first section and the second section to a seventh width at the interface between the second section and the third section.
15 . The device of claim 1 , wherein the eighth width is 300 nanometers.
16 . The method of claim 14 , wherein the III-V rib transition segment is formed in a rib layer of the III-V semiconductor structure, the rib layer comprising a p-type III-V material.
17 . The method of claim 12 , wherein the silicon transition segment formed in the silicon layer extends across the first, second, and third sections, wherein:
the silicon transition segment has a constant width of an eighth width within the first section;
and
the silicon transition segment has a constant width of the ninth width within the third section, the eight width being less than the ninth width.
18 . The method of claim 12 , further comprising:
forming an anode, the anode overlapping the III-V slab transition segment in at least the first section; and
forming a cathode adjacent to the III-V slab transition segment.
19 . The method of claim 12 , wherein the silicon layer has a thickness between 150 nanometers and 350 nanometers.
20 . The method of claim 12 ,
further comprising forming a dielectric layer separating the III-V structure from the silicon layer;
wherein the III-V structure comprises an n-type layer between the III-V slab transition segment and the dielectric layer.