The invention relates to a receiving device (Rx1_b) capable of receiving an optical signal emitted by an emitting device including a light source for emitting the optical signal, the optical signal being transmitted by a passive optical network having wavelength division multiplexing, the receiving device including: an optical amplifier (Amp_b) for amplifying the optical signal received from the emitting device; an optical detector (D_b) capable of detecting data in the amplified optical signal; an optical reflector (Ref_b) configured to return the amplified optical signal toward the emitting device, such as to tune the wavelength of the optical signal emitted by the emitting device by means of a round trip of the optical signal between the emitting device and the optical reflector.