Patent ID: 7848660

Claim:
An optical transmitter comprising: a coherent light source that is configured to output continuous wave optical energy; a frequency control loop that measures and controls a transmission frequency of said coherent light source, the frequency control loop comprising an etalon frequency control device that is configured to receive the continuous wave optical energy output by the coherent light source and to generate an electrical control signal to lock the transmission frequency of the continuous wave optical energy to a desired value; a modulator that is configured to be coupled to the output of the etalon frequency control device and is configured to amplitude modulate the continuous wave optical energy with a modulation signal to output a modulated optical signal; an optical filter having a controllable center frequency that is configured to filter the modulated optical signal output by the modulator to output a filtered modulated optical signal having a first sideband substantially attenuated a second sideband substantially unattenuated; and wherein said etalon frequency control device is configured to generate the electrical control signal that controls the coherent light source so that said controllable center frequency is locked to said transmission frequency plus a predetermined spacing such that a response of the optical filter does not drift causing either attenuation of desired portions of the second sideband or passing of undesired portions of the first sideband.