Optoelectronic system comprising several sections having respective functions coupled by evanescent coupling and production process

Optoelectronic system comprising at least three sections (A, B, C) corresponding to specific respective functions and having different respective band gap energies, characterized in that these three sections consist of at least two layers (20, 30) superposed by epitaxy, the upper layer (30) being etched in order to define said sections in the form of two separate end sections (A, C) defined in the upper layer (30) on each side of an intermediate section (B) defined in the lower layer (20), and to allow coupling between the intermediate section (B) and each of the end sections (A, C) which flank it, by evanescent coupling, in which system the length (L) of the intermediate section (B) is such that the product (K×L), in which (K) represents the coupling coefficient of a grating of the intermediate section (B), is of the order of 1.