Patent ID: 7209660

Claim:
An optical communications system for communicating information comprising: a receiver subsystem comprising: an optical splitter for splitting a composite optical signal having at least two subbands of information and at least one tone into at least two optical signals; and at least two heterodyne receivers, each heterodyne receiver coupled to receive one of the optical signals from the optical splitter for recovering information from one of the subbands contained in the optical signal, each heterodyne receiver comprising: a heterodyne detector for mixing an optical local oscillator signal with the optical signal to produce an electrical signal which includes a frequency down-shifted version of the subband and the tone of the optical signal; and a signal extractor coupled to the heterodyne detector for mixing at least one portion of the frequency down-shifted subband with the frequency down-shifted tone to produce a frequency component containing the information; wherein a signal extractor of one of the at least two heterodyne receivers comprises two extraction paths and a combiner, each extraction path configured to process a different one of at least two sidebands within the electrical signal, wherein a first extraction path of the two extraction paths is configured to process only an upper sideband within the electrical signal, wherein said processing of the upper sideband comprises mixing the frequency down-shifted tone with the upper sideband, and a second extraction path of the two extraction paths is configured to process only a lower sideband within the electrical signal, wherein said processing of the lower sideband comprises mixing the frequency down-shifted tone with the lower sideband.