A system for stabilizing an output optical power from a laser source against drifts induced by temperature and/or aging, said output optical power including a target optical-modulation amplitude around a target average value includes: a power sensor for sensing the output optical power from the laser source and generating a power sensing signal indicative thereof, and a controller sensitive to the power sensing signal and configured for selectively adjusting the bias (I.sub.B) and modulation (I.sub.M) currents of the laser source by: detecting an error between the actual average output optical power from the laser source and the target average value,comparing the error against a given error threshold, and when the error reaches the threshold adjusting the bias (I.sub.B) and modulation (I.sub.M) currents to bring the output optical power from the laser source (1) back to the target average value (P.sub.target) and the target optical modulation amplitude (OMA.sub.target) around the target average value (P.sub.target).