An all-optical real-time chromatic dispersion
(CD) monitoring technique is proposed and demonstrated
for 40 Gbit/s differential phase-shifts keying (DPSK)
signal, utilizing the cross modulation effects of semicon-
ductor optical amplifier (SOA). The optical power of the
output spectral components, which is from the probe’s
frequency up to the signal bandwidth, is used for CD
monitoring. This technique provides a wide monitoring
range with large variation scale. The impacts of the
polarization mode dispersion (PMD) and the optical
signal-to-noise ratio (OSNR) on the CD monitoring results
are theoretically analyzed and then experimentally inves-
tigated, showing that they have slight influence on the
monitoring results within a certain range. Furthermore,
simulated results for quadrature phase shift keying (QPSK)
signal at 80 Gbit/s are also demonstrated, indicating that
this technique is suitable for advanced modulated format as
well.

• Chromatic dispersion monitoring using semiconductor optical amplifier