An apparatus for signal modulation in a point-to-multipoint optical network is configured to modulate a single-wavelength carrier wave before distribution towards optical receivers of a first type adapted for intensity detection and a second type adapted for optical field detection. The apparatus includes a first module configured to modulate the carrier wave by varying the intensity of the carrier wave to represent data intended for the first type of receivers, and by controlling the phase and/or polarization of the carrier wave during selected periods. The apparatus includes a second module configured to modulate the carrier wave by varying the phase and/or polarization of the carrier wave to represent data intended for the second type of receivers, and by varying the intensity of the carrier wave during selected periods.