The present invention provides for an optical transmission system for generating light signals at a plurality of predetermined wavelengths on an output fiber. The system has a plurality of modulated laser sources coupled to the output fiber and a feedback loop connected to the output fiber. The feedback loop includes a first subloop which generates electrical signals indicative of a total amount of light carried on the output fiber, and a second subloop which generates electrical signals indicative of an amount of light carried on the output fiber at the predetermined wavelengths. A control unit coupled to the plurality of laser sources receives the electrical signals from the first and second subloops and adjusts the laser source output wavelengths so that the output of each laser source is centered at one of the predetermined wavelengths. A comb filter is in the second subloop for transmitting light signals at the predetermined wavelengths.