A photodiode which includes a core of a first waveguide that terminates in a tapered termination that extends above a core, made of germanium or of SiGe, of a second waveguide, a matching strip that extends opposite the tapered termination on one side and opposite the core of the second waveguide on the opposite side, this matching strip being coupled optically to the core of the second waveguide by an evanescent coupling and including a first zone inside which its effective propagation index is equal to the effective propagation index of a second zone of the tapered termination, these first and second zones optically coupling the tapered termination to the matching strip through a modal coupling, and a low-index layer that extends between the matching strip and the tapered termination.