Waveguide crossings with a non-contacting arrangement
Structures for a waveguide bend and methods of fabricating a structure for a waveguide bend. A first waveguide core has a first section, a second section, and a first waveguide bend connecting the first section with the second section. The first waveguide core has a first side surface extending about an outer radius of the first waveguide bend. A second waveguide core also has a first section, a second section, and a second waveguide bend connecting the first section with the second section. The second waveguide core has a second side surface extending about an outer radius of the second waveguide bend. The first waveguide bend is spaced from the second waveguide bend in a first non-contacting relationship with a gap between the first side surface and the second side surface. The gap has a perpendicular distance selected to permit optical signal transfer between the first and second waveguide bends.
1. A structure comprising:
a first waveguide core including a first section, a second section, and a first waveguide bend connecting the first section with the second section, the first waveguide core having a first side surface extending about an outer radius of the first waveguide bend; and
a second waveguide core including a first section, a second section, and a second waveguide bend connecting the first section with the second section, the second waveguide core having a second side surface extending about an outer radius of the second waveguide bend,
wherein the first section of the first waveguide core is substantially straight and aligned along a first longitudinal axis, the first section of the second waveguide core is substantially straight and aligned along a first longitudinal axis, the first longitudinal axis of the first waveguide core is substantially collinear with the first longitudinal axis of the second waveguide core, the first waveguide bend is spaced from the second waveguide bend in a first non-contacting relationship with a first gap between the first side surface and the second side surface, and the first gap has a perpendicular distance selected to permit optical signal transfer between the first waveguide bend and the second waveguide bend.
2. The structure of claim 1 wherein the first waveguide bend includes a first plurality of segments arranged in a first curved arc.
3. The structure of claim 2 wherein the second waveguide bend includes a second plurality of segments arranged in a second curved arc.
4. The structure of claim 2 wherein the first plurality of segments are separated by spaces, and the spaces are filled by a dielectric material.
5. The structure of claim 1 wherein the first side surface of the first waveguide bend of the first waveguide core is convexly curved, and the first side surface of the first waveguide bend of the second waveguide core is convexly curved.
6. The structure of claim 1 wherein the second section of the first waveguide core is substantially straight and aligned along a second longitudinal axis, the second section of the second waveguide core is substantially straight and aligned along a second longitudinal axis, and the second longitudinal axis of the first waveguide core is substantially collinear with the second longitudinal axis of the second waveguide core.
7. The structure of claim 6 wherein the first longitudinal axis of the first waveguide core is angled at a first angle relative to the second longitudinal axis of the first waveguide core, and the first longitudinal axis of the second waveguide core is angled at a second angle relative to the second longitudinal axis of the second waveguide core.
8. The structure of claim 7 wherein the first angle is a right angle, and the second angle is a right angle.
9. The structure of claim 1 wherein the first waveguide bend of the first waveguide core includes a first curved section, a second curved section, and a first non-curved section connecting the first curved section with the second curved section, and the first waveguide bend of the second waveguide core includes a first curved section, a second curved section, and a second non-curved section connecting the first curved section with the second curved section.
10. The structure of claim 9 wherein the first non-curved section and the second non-curved section are substantially straight, and the first non-curved section and the second non-curved section are separated by the first gap.
11. The structure of claim 10 wherein the first non-curved section has a first length and the second non-curved section has a second length that is substantially equal to the first length.
12. The structure of claim 10 wherein the first non-curved section has a first length and the second non-curved section has a second length that not equal to the first length.
13. The structure of claim 1 wherein the first gap is filled by a dielectric material, and the first waveguide core and the second waveguide core are comprised of single-crystal silicon.
14. A structure comprising:
a first waveguide core including a first section, a second section, a first waveguide bend connecting the first section with the second section, and a third waveguide bend connected with the second section of the first section of the first waveguide core, the first waveguide core having a first side surface extending about an outer radius of the first waveguide bend; and
a second waveguide core including a first section, a second section, a second waveguide bend connecting the first section with the second section, and a fourth waveguide bend connected with the second section, the second waveguide core having a second side surface extending about an outer radius of the second waveguide bend,
wherein the first waveguide bend is spaced from the second waveguide bend in a first non-contacting relationship with a first gap between the first side surface and the second side surface, and the first gap has a perpendicular distance selected to permit optical signal transfer between the first waveguide bend and the second waveguide bend, the third waveguide bend spaced from the fourth waveguide bend in a second non-contacting relationship by a second gap between the first side surface and the second side surface, and the second gap has a perpendicular distance selected to permit optical signal transfer from the first waveguide bend to the second waveguide bend.
15. The structure of claim 14 wherein the first waveguide bend and the third waveguide bend are curved in opposite directions, and the second waveguide bend and the fourth waveguide bend are curved in opposite directions.
16. A method comprising:
patterning a layer with lithography and etching processes to form a first waveguide bend of a first waveguide core and a second waveguide bend of a second waveguide core,
wherein the first section of the first waveguide core is substantially straight and aligned along a first longitudinal axis, the first section of the second waveguide core is substantially straight and aligned along a first longitudinal axis, the first longitudinal axis of the first waveguide core is substantially collinear with the first longitudinal axis of the second waveguide core, the first waveguide core has a first side surface extending about an outer radius of the first waveguide bend, the second waveguide core having a second side surface extending about an outer radius of the second waveguide bend, the first waveguide bend is spaced from the second waveguide bend in a first non-contacting relationship with a gap between the first side surface and the second side surface, and the gap has a perpendicular distance selected to permit optical signal transfer between the first waveguide bend and the second waveguide bend.
17. The method of claim 16 wherein the first waveguide bend and/or the second waveguide bend is patterned with the lithography and etching processes to include a plurality of segments arranged in a first curved arc.
18. The method of claim 16 wherein the first waveguide bend and/or the second waveguide bend is patterned with the lithography and etching processes to include a first curved section, a second curved section, and a first non-curved section connecting the first curved section with the second curved section.