Specialty Optical Fibers Handbook

dispersion curve D(l) is linear is more valid for the Tx fiber than for the DCF. In

reality, D

2

(l) may have significant quadratic and cubic terms in the Taylor

expansion. For 40-Gbps transmission line design, it is useful to define the relative

dispersion curvature RDC ¼ D

00

=D, which can also be matched between Tx fiber

and DCF. The term residual dispersion refers to the net dispersion of a compen-

sated span or a concatenated series of compensated spans as illustrated in

Fig. 5.7. If the RDS values of the Tx fiber and DCF have been matched, then

the residual dispersion will be essentially parabolic across a band. In cases in

which the RDC can also been matched, then the residual dispersion takes on a

cubic shape [25]. It is this residual dispersion ...