Patent ID: 8718476

Claim:
An optical transmission system comprising: an optical source for transmitting an optical signal at a carrier frequency, wherein the optical source is driven by a drive current, and wherein the carrier frequency is varied based on the amplitude of the drive current; an encoder providing data to be modulated onto the optical signal; a phase modulator for receiving the data provided by the encoder, and modulating the data onto the optical signal using a phase shift keyed format to generate a phase shift keyed optical signal; an optical discriminator for receiving the phase shift keyed optical signal, the optical discriminator having an output, wherein the optical discriminator is variable based on temperature; and, a controller adapted to dither the carrier frequency of the optical signal and the phase shift keyed optical signal by varying the amplitude of the drive current to cause the optical signal to have multiple carrier frequencies in sequence during operation of the transmission system, the controller further adapted to obtain relationships between a bit error rate of the received optical signal and each of the multiple carrier frequencies, the controller being further adapted to tune the optical discriminator or the carrier frequency in dependence on the relationships by adjusting the temperature of the optical discriminator or the optical source.