Patent ID: 7366424

Claim:
An apparatus for creating alternate block phase inversion coded representations of an optical communication signal, the apparatus comprising: a modulator adapted to modulate a first and a second beam of continuous wave electromagnetic radiation with a source signal so that the first and second beams combine to produce streams of asserted and unasserted data bits, to assemble modulated portions of said first and second beams into a first electromagnetic radiation signal of interposed regular and alternate data bit sequences comprising blocks of asserted non return to zero coded data bits, each of said data bit sequences being interposed by blocks of unasserted data bits, and to assemble modulated portions of said first and second beams into a second electromagnetic radiation signal of interposed regular and alternate data bar bit sequences comprising blocks of asserted non return to zero coded data bar bits representing said unasserted data bits, each of said data bar bit sequences being interposed by blocks of unasserted data bar bits representing said asserted data bits; and means for modulating said first and second electromagnetic radiation signal using information provided by said source signal, to shift the phase of said alternate data bit sequences and said alternate data bar bit sequences.