Patent ID: 7146103

Claim:
An optical communications system comprising: a transmitter subsystem comprising: at least two optical transmitters, each configured to generate an optical signal containing a subband of information, each optical signal having a different polarization, wherein each optical signal has a lower optical sideband and an upper optical sideband; an optical combiner coupled to the optical transmitters configured to optically combine the optical signals into a composite optical signal; an optical filter coupled to the optical combiner, wherein the optical filter is configured to select one optical sideband from each optical signal, wherein the optical filter is configured to select a lower optical sideband from a first optical signal and an upper optical sideband from a second optical signal; a first optical tap coupled between the optical combiner and the optical filter configured to tap a portion of the combined optical signals leaving the optical combiner; and a second optical tap coupled to the optical filter configured to tap a portion of the composite optical signal leaving the optical filter; and a wavelength-locking device coupled to the optical transmitters configured to lock a freciuency separation of the combined optical signals to a predetermined value, the wavelength-locking device is coupled to the first optical tap and to the second optical tap and configured to lock the frequency separation based on mutiple ratios of the portions tapped by the optical taps.