In constructing a fiber-based “test multiplexer” for very high symbol rates, e.g.,
640 Gbaud, the effect of CD has to be taken into account. The following consideration
shows this as regards CD. The optical pulses at the output of the “test multiplexer”
have passed different fiber lengths. Thus they suffer different pulse broadening due to
CD. The generation of data signals having a symbol rate of 640 Gbaud from a base
symbol rate of 10 Gbaud requires a 10–640 Gbaud “test multiplexer.” Using a delay
as determined by a PRBS word length with 2
7
–1 bit gives delays with the fiber lengths
of 1.28 m, 0.64 m, 0.32 m, 0.16 m, 0.08 m, and 0.04 m. The maximum difference of
fiber length passed by the pulses in the six stages of the “test multiplexer” adds