Patent ID: 7346279

Claim:
An optical communications system comprising: a transmitter subsystem comprising: a pilot tone generator for generating a pilot tone at a pilot tone frequency; a reference clock generator for generating a reference clock signal at a reference clock frequency; a signal generator coupled to the pilot tone generator and the reference clock generator, wherein the signal generator includes an incoherent reference signal modulator configured to generate a reference signal by using the reference clock signal to modulate the pilot tone, and wherein the signal generator is configured to combine the reference signal with a subcarrier channel into an information signal; and an optical modulator coupled to the signal generator for generating an optical signal, the optical signal including the reference signal and the subcarrier channel; wherein the signal generator is further configured to combine additional subcarrier channels into the information signal, wherein each subcarrier channel includes a coherently modulated data stream and is located at a unique subcarrier frequency.