Heterogeneously integrated photonic platform supporting large effective mode area waveguides and thermally optimized active components

A device comprising:

• first, second, third, fourth and fifth layers fabricated on a common substrate;
• wherein the first layer comprises an active waveguide structure, having a first layer waveguide core supporting a first optical mode, the second layer comprises a passive waveguide structure having a second layer waveguide core positioned at a second vertical distance from the substrate and supporting a second optical mode, the third layer comprises a passive waveguide structure having a third layer waveguide core, positioned at a third vertical distance from the substrate where the third vertical distance is smaller than the second vertical distance, supporting a third optical mode, the fourth layer comprises a heatsink thermally coupled to the first layer, and the fifth layer, having a fifth layer waveguide core with a first end surface, perpendicular to an optical axis of the fifth layer, at least partly butt-coupled to an end surface of the first layer waveguide core, and a second end surface, perpendicular to the optical axis of the fifth layer, that is but not butt-coupled to the second layer waveguide core, comprises an intermediate waveguide structure, the fifth waveguide core supporting an intermediate optical mode, different from the first optical mode;
• wherein an effective mode area characterizing the third optical mode, at an axial position where the third waveguide core does not underlie any position of the second waveguide core, is larger than an effective mode area characterizing the second optical mode, at an axial position where the second waveguide core does not underlie any position of the fifth layer;
• and
• wherein a tapered waveguide structure in at least one of the second and fifth layers facilitates efficient adiabatic transformation between the second optical mode and the intermediate optical mode;
• wherein a tapered waveguide structure in at least one of the second and third layers facilitates efficient adiabatic transformation between the second optical mode and the third optical mode;
• wherein each of the second layer waveguide core and the third layer waveguide core comprises at least one of silicon nitride, silicon-oxynitride, titanium dioxide, tantalum-pentoxide, doped silicon-dioxide, lithium-niobate, and alumina;
• and
• wherein no adiabatic transformation occurs between the intermediate optical mode and the first optical mode.