Abstract: The method of controlling and/or monitoring an optical transmission of message signals over an optical line in a repeater station includes providing a device (45) for generating further optical secondary signals from the received optical secondary signals without generating a stable optical carrier signal for the secondary signals in the device (45). This device (45) includes a hybrid circuit (451) for splitting the received optical secondary signals to form a first branched optical signal portion and a second branched optical signal portion, an optical monitoring and/or control receiver (454) for generating control and/or monitoring signals (456) from the first branched optical signal portion and an optical modulating device (458) controllable by the control and/or monitoring signals.