Metamaterial layers for use with optical components
Structures including an optical component, such as an edge coupler, and methods of fabricating such structures. The structure includes a substrate, a waveguide core over the substrate, and a metamaterial layer positioned in a vertical direction between the waveguide core and the substrate. The metamaterial layer includes a set of elements separated by a set of gaps and a dielectric material in the set of gaps.
1 . A structure comprising:
a silicon-on-insulator substrate including a buried oxide layer and a semiconductor substrate;
a first waveguide core over the buried oxide layer; and
a metamaterial layer positioned in a vertical direction between the first waveguide core and the semiconductor substrate, the metamaterial layer including a plurality of elements separated by a plurality of gaps and a first dielectric material in the plurality of gaps,
wherein the first waveguide core comprises a second dielectric material different from the first dielectric material, the plurality of elements are positioned in a one-dimensional array, the first waveguide core has a first longitudinal axis, each of the plurality of elements is elongated with alignment along a second longitudinal axis, and the second longitudinal axis is aligned parallel to the first longitudinal axis.
2 . The structure of claim 1 wherein the plurality of elements comprise single-crystal silicon, and the first dielectric material comprises silicon dioxide.
3 . The structure of claim 1 wherein the plurality of elements comprise single-crystal silicon, and the second dielectric material comprises silicon nitride.
4 . The structure of claim 1 wherein the plurality of elements comprise single-crystal silicon, and the second dielectric material comprises silicon-carbon nitride or hydrogenated silicon-carbon nitride.
5 . The structure of claim 1 wherein the first waveguide core overlaps with at least one of the plurality of elements.
6 . The structure of claim 1 wherein the first waveguide core has a non-overlapping arrangement with at least one of the plurality of elements.
7 . The structure of claim 1 wherein the first waveguide core is centered over the plurality of elements.
8 . The structure of claim 1 wherein the first waveguide core includes an inverse taper, and the semiconductor substrate is solid beneath the inverse taper.
9 . The structure of claim 1 further comprising:
a dielectric layer over the plurality of elements,
wherein the dielectric layer is arranged between the metamaterial layer and the first waveguide core, the dielectric layer comprises the first dielectric material, the plurality of elements are embedded in the dielectric layer, and the first dielectric material is silicon dioxide.
10 . The structure of claim 1 further comprising:
a back-end-of-line stack including a plurality of dielectric layers over the first waveguide core; and
a second waveguide core on the plurality of dielectric layers.
11 . The structure of claim 10 further comprising:
a light source configured to provide light to an edge coupler including the first waveguide core and the second waveguide core,
wherein the metamaterial layer is configured to reflect the light away from the semiconductor substrate, and the light source is an optical fiber or a semiconductor laser.
12 . The structure of claim 11 wherein the first waveguide core is terminated by an end surface, and the light source is configured to provide the light in a mode propagation direction aligned with the end surface.
13 . The structure of claim 10 wherein the second waveguide core is truncated at opposite ends, and the second waveguide core overlaps with a portion of the first waveguide core.
14 . The structure of claim 10 the second waveguide core is truncated at opposite ends, and further comprising:
a third waveguide core on the plurality of dielectric layers, the third waveguide core laterally spaced from the second waveguide core, and the third waveguide core truncated at opposite ends.
15 . The structure of claim 14 further comprising:
a fourth waveguide core on the plurality of dielectric layers, the fourth waveguide core laterally spaced from the second waveguide core, the fourth waveguide core truncated at opposite ends, and the second waveguide core laterally located between the third waveguide core and the fourth waveguide core.
16 . The structure of claim 1 further comprising:
a first dielectric layer between the first waveguide core and the metamaterial layer, the first dielectric layer comprising the first dielectric material.
17 . The structure of claim 16 further comprising:
a second dielectric layer between the metamaterial layer and the semiconductor substrate.
18 . A method comprising:
forming a waveguide core over a buried oxide layer of a semiconductor-on-insulator substrate; and
forming a metamaterial layer positioned in a vertical direction between the waveguide core and a semiconductor substrate of the semiconductor-on-insulator substrate,
wherein the metamaterial layer includes a plurality of elements separated by a plurality of gaps and a first dielectric material in the plurality of gaps, the waveguide core comprises a second dielectric material different from the first dielectric material, the plurality of elements are positioned in a one-dimensional array, the waveguide core has a first longitudinal axis, each of the plurality of elements is elongated with alignment along a second longitudinal axis, and the second longitudinal axis is aligned parallel to the first longitudinal axis.
19 . The method of claim 18 wherein the waveguide core is terminated by an end surface, and further comprising:
placing a light source adjacent to the end surface of the waveguide core,
wherein the light source is configured to provide the light in a mode propagation direction aligned with the end surface of the waveguide core, and the metamaterial layer is configured to reflect the light away from the semiconductor substrate.