Integrated waveguide structure with pockels layer having a selected crystal orientation
Aspects of the invention are directed to an electro-optical device having a layer structure including a substrate, an electrically insulating layer on top of the substrate, a bonding layer on top of the electrically insulating layer, a Pockels layer on top of the bonding layer, a waveguide core on top of the Pockels layer, and a cladding layer cladding both the waveguide core and the Pockels layer, the latter coated by the cladding layer. The Pockels layer is a layer of a crystalline first material having a Pockels coefficient between 10 pm/V and 10 000 pm/V. The waveguide core includes a second material, which can be crystalline. The device can be adapted to optically couple radiation into and/or from the waveguide core. Each of the first material and the second material has a larger refractive index than the electrically insulating layer and the cladding layer for said radiation.
1. An electro-optical device with a layer structure, the device comprising:
a substrate;
an electrically insulating layer on top of the substrate;
a bonding layer on top of the electrically insulating layer;
a Pockels layer on top of the bonding layer;
a waveguide core including a base, an upper surface, and opposing sidewalls extending from the base to the upper surface, the base on top of the Pockels layer; and
a cladding layer cladding both the waveguide core and the Pockels layer, the latter being directly coated by the cladding layer, and the waveguide core embedded in the cladding layer such that the cladding layer directly contacts the opposing sidewalls and the upper surface,
wherein:
the Pockels layer comprises a layer of a first material, which is crystalline and has a Pockels coefficient between 10 pm/V and 10 000 pm/V;
the waveguide core comprises a second material;
the device is adapted to optically couple radiation into and/or from the waveguide core, in operation of the device; and
each of the first material and the second material has a larger refractive index than the electrically insulating layer and the cladding layer for said radiation.
2. The electro-optical device according to claim 1 , wherein:
the first material has a Pockels coefficient that is between about 100 and about 2000 pm/V.
3. The electro-optical device according to claim 1 , wherein the layer structure does not comprise any interface layer between the waveguide core and the Pockels layer.
4. The electro-optical device according to claim 1 , wherein:
the layer structure comprises a residual interface layer between the waveguide core and the Pockels layer; and
the residual interface layer does not protrude laterally from the waveguide core, such that the cladding layer is in direct contact with the Pockels layer at a periphery of the waveguide core.
5. The electro-optical device according to claim 1 , wherein the first material is selected from a group consisting of BaxSr1-xTiO3, Pb[ZrxTi1-x]O3, [PbyLa1-y][ZrxTi1-x]O3, KNbO3, BiFeO3, and KTaO3.
6. The electro-optical device according to claim 1 , wherein the second material is selected from a group consisting of Si, Si3N4, SiOxNy, Ta2O5, AlN, AlOx, AlON, HfOx, TiOx, and ZrOx.
7. The electro-optical device according to claim 1 , wherein the second material is selected from a group consisting of BaxSr1-xTiO3, Pb[ZrxTi1-x]O3, [PbyLa1-y][ZrxTi1-x]O3, KNbO3, BiFeO3, and KTaO3.
8. The electro-optical device according to claim 1 , wherein one or each of the electrically insulating layer and the cladding layer comprises a material that is selected from a group consisting of SiO 2 , Si3N4, SiOxNy, AlN, AlOx, AlON, HfOx, Ta2O5, TiOx, and ZrOx.
9. The electro-optical device according to claim 1 , wherein the bonding layer comprises a material that is selected from the group consisting of SiO2 and Al2O3.
10. The electro-optical device according to claim 5 , wherein the first material comprises BaTiO3.
11. The electro-optical device according to claim 10 , wherein the electrically insulating layer comprises SiO2.
12. The electro-optical device according to claim 11 , wherein the electrically insulating layer and the substrate respectively correspond to a buried oxide layer and a silicon substrate of a silicon-on-insulator substrate.
13. The electro-optical device according to claim 1 , wherein:
the substrate, the electrically insulating layer, the bonding layer, the Pockels layer, the waveguide core and the cladding layer are successively stacked along a stacking direction z; and
the waveguide core has an average thickness that is between about 50 nm and about 500 nm, said thickness measured along a stacking direction z.
14. The electro-optical device according to claim 13 , wherein the waveguide core has an average width that is between about 10 nm and about 1000 nm, said width being measured perpendicularly to the stacking direction and in-plane with the waveguide core.
15. The electro-optical device according to claim 13 , wherein the Pockels layer has an average thickness that is between about 10 nm and about 1000 nm, as measured along a stacking direction z.
16. The electro-optical device according to claim 1 , wherein the device is configured as one of a modulator, a switch, and an electric-field sensor.
17. A silicon photonic circuit, comprising the electro-optical device according to claim 1 integrated therein.
18. The silicon photonic circuit of claim 17 , wherein the electro-optical device is co-integrated, in the silicon photonic circuit, with one or more integrated circuit components.