An optical coupler in a vertical configuration, comprising: - a first waveguide extending in a longitudinal direction, the first waveguide including a first core and a first cladding each having an optical index (nc1, ng1), the first core is made from a material belonging to column III of the periodic table formed with a material according to column V of the periodic table, and - a second waveguide distinct from the first waveguide, extending parallel to the first waveguide, the second waveguide including a second core and a second cladding, the optical coupler further comprising: - a third waveguide distinct from the first and second waveguides (12, 14) and extending parallel to the first and second waveguides (12, 14), the third waveguide being arranged between the first waveguide and the second waveguide in a transverse direction perpendicular to the longitudinal direction and having parameters influencing the evanescent wave coupling between the first waveguide and the second waveguide, those parameters being chosen such that the coupling is greater than 15%, the third waveguide including an upper layer, a lower layer and a third core, said parameters of the third waveguide influencing the evanescent wave coupling between the first waveguide and the second waveguide being the dimensions in two perpendicular directions as well as the optical indices of the upper layer, the lower layer and the third core, the optical coupler including a substrate, made from a first material that is preferably silicon, in which the second waveguide and the third waveguide are buried, the first waveguide being arranged in contact with the substrate and made from a material different from the first material, characterized in that the second core and the second cladding have an optical index (nc2, ng2), the optical index of the first core of the first waveguide being lower than the optical index of the second cladding of the second waveguide. - a first waveguide extending in a longitudinal direction, the first waveguide including a first core and a first cladding each having an optical index (nc1, ng1), the first core is made from a material belonging to column III of the periodic table formed with a material according to column V of the periodic table, and - a second waveguide distinct from the first waveguide, extending parallel to the first waveguide, the second waveguide including a second core and a second cladding, - a third waveguide distinct from the first and second waveguides (12, 14) and extending parallel to the first and second waveguides (12, 14), the third waveguide being arranged between the first waveguide and the second waveguide in a transverse direction perpendicular to the longitudinal direction and having parameters influencing the evanescent wave coupling between the first waveguide and the second waveguide, those parameters being chosen such that the coupling is greater than 15%, the third waveguide including an upper layer, a lower layer and a third core, said parameters of the third waveguide influencing the evanescent wave coupling between the first waveguide and the second waveguide being the dimensions in two perpendicular directions as well as the optical indices of the upper layer, the lower layer and the third core,