III-V photonic device integrated on silicon

A photonic device (D1) comprising a stack of layers on a substrate (SUB) in a stacking direction (Z), said stack comprising:

• a first waveguide (WG1) having a core comprising a plurality of stacked layers, with each layer of said plurality of layers, being made of a III-V type semiconductor material;
• a second waveguide (WG2) having a silicon core;
• an optical coupling structure (SC) for transferring at least part of an optical signal propagated from the first waveguide (WG1) to the second waveguide (WG2), or vice versa, with the optical coupling structure (SC) comprising:
• a first extension of the core of the first waveguide (WG1);
• a second extension of the core of the second waveguide (WG2) disposed below said first extension and disposed opposite said first extension;
• a coating structure made of a coating material having a refractive index (n30) ranging between:
• on the one hand, the refractive index of silicon;
• and, on the other hand, the highest refractive index from among those of said III-V type semiconductor materials, for a predetermined wavelength;
• the coating structure being disposed between the second extension and the first extension at least in the stacking direction (Z).