Self-alignment for apparatus comprising photonic device

1. A method to fabricate an apparatus,

wherein the apparatus comprises

a photonic device with at least a first waveguide having a light-conducting core layer bounded by at least one cladding layer, and

at least a second waveguide having a light-conducting core layer bounded by at least one cladding layer,

wherein the first waveguide is aligned to couple with the second waveguide, wherein alignment of the first waveguide with the second waveguide with respect to at least one axis C coincides with at least one stop area of the photonic device resting on a stop surface of a corresponding support structure on a substrate, wherein the at least one stop area is a stop in a recess from a surface of the photonic device,

the method comprising:

at least one of the recess is formed by etching of the photonic device or the support structure is formed by etching of the substrate, wherein each of the etching of the photonic device and the etching of the substrate is selective with respect to at least one interface between two materials in respectively the photonic device or the substrate; and

at least one of the core layer of the first waveguide or the core layer of the second waveguide is deposited by selective area growth,

in which the selective area growth includes

removing a dielectric layer to expose at least one of a first surface of a first semiconductor material of the first waveguide or a first surface of a second semiconductor material of the second waveguide and create at least one of a growth window at the first surface of the first waveguide or a growth window at the first surface of the second waveguide, and

at least one of growing a third semiconductor material in the growth window at the first surface of the first waveguide or growing a fourth semiconductor material in the growth window at the first surface of the second waveguide,

wherein at least one of (i) a first thickness of the core layer of the first waveguide in the vicinity of the recess is different from a second thickness of the core layer in the first waveguide or (ii) a first thickness of the core layer of the second waveguide in the vicinity of the support structure is different from a second thickness of the core layer in the second waveguide.

2. The method according to claim 1 , wherein the two materials are chosen from the materials of at least one of the core layer, a light emitting layer inside the core layer, an electrical cladding layer inside the core layer, or a cladding layer, that form part of the first waveguide of the photonic device.

3. The method according to claim 1 , wherein either during the etching of the photonic device, the core layer of the first waveguide is removed, or during the etching of the substrate, the core layer of the second waveguide is removed.

4. The method according to claim 2 , wherein during fabrication of at least one layer of the core layer, light emitting layer inside the core layer, the electrical cladding layer inside the core layer, or a cladding layer, that forms part of the first waveguide of the photonic device, the at least one layer is extended laterally to the location of the recess.

5. The method according to claim 4 , wherein an auxiliary cladding layer with a thickness that corresponds to a desired offset along the axis C between a boundary of the core layer of the first waveguide and a boundary of the core layer of the second waveguide is inserted between the core layer and one of the cladding layers of said first waveguide.

6. The method according to claim 1 , wherein the two materials are chosen from materials of at least one of the core layer or a cladding layer, that form part of the second waveguide which in turn forms part of the substrate.

7. The method according to claim 6 , wherein during fabrication of at least one layer of the core layer, or a cladding layer, that forms part of the second waveguide, the at least one layer is extended laterally to a location of the support structure.

8. The method according to claim 7 , wherein an auxiliary cladding layer with a thickness that corresponds to a desired offset along the axis C between a boundary of the core layer of the first waveguide and a boundary of the core layer of the second waveguide is inserted between the core layer and one of the cladding layers of said second waveguide.

9. The method according to claim 1 , wherein at least one of an additional layer is deposited in the recess after the etching of the photonic device or an additional layer is deposited on the support structure after the etching of the substrate, with a thickness that corresponds to a desired offset along the axis C between a boundary of the core layer of the first waveguide and a boundary of the core layer of the second waveguide.

10. The method according to claim 1 , wherein at least one of the etching of the photonic device or the etching of the substrate is slowed down by at least a factor of 3 upon or before reaching said at least one interface in the at least one of the photonic device or the substrate.

11. The method according to claim 1 , wherein at least one of the etching of the photonic device or the etching of the substrate is slowed down by at least a factor of 5 upon or before reaching said at least one interface in the at least one of the photonic device or the substrate.