Multigigabit subcarrier multiplexed coherent lightwave system

A wideband coherent detection optical communications system using two microwave subcarriers to transmit 8 Gb/s with a RF bandwidth efficiency of 1 b/s/Hz is described. It is demonstrated that two subcarriers each carrying 4 Gb/s QPSK, compactly spaced at just twice the data rate, can achieve a receiver sensitivity ( eta P) of -26.5 dBm with as little as 0.5-dB crosstalk between subcarriers. How the various components affect the overall performance of QPSK-SCM systems, including a CNR model for multichannel systems is discussed.<
>