Measurement of residual chromatic dispersion of a 40Gbit/s RZ signal via spectral broadening

We examine the spectrum of a 40Gbit/s return-to-zero (RZ) data stream which has been broadened by self phase modulation in a nonlinear fiber. Spectra were recorded as the residual chromatic dispersion at the input of the nonlinear fiber was varied using a tunable dispersion element. We show that spectral broadening can provide a useful measure of the residual chromatic dispersion of the data stream.