| Abstract: |
There has recently been a renewed effort to develop coherent optical
communication systems. In particular, differential phase-shift keying
(DPSK), which does not require a local oscillator to perform decoding,
has focused the attention and is perceived to be the promising candidate
for future optical communication systems updates.
Modulation formats based on phase show an increased robustness to
nonlinear impairments and allow a higher spectral efficiency since both
in-phase and quadrature dimensions of the signal space are available to
encode information. They also outperforms their intensity counterparts
in terms of sensitivity since a 3 dB improvement can be achieved when
balanced detection is used. Nevertheless, DPSK-based formats show a
different behavior to noise accumulated along the propagation.
Noise-induced power fluctuations are converted into phase fluctuations
by the Kerr effect and become a penalty source which limits the
transmission system reach. In this context, there have been intense
research activities for evaluating phase uncertainties but the previous
studies assume an analytically determined pulse shape and a
constant-dispersion optical link which is far from reflecting the actual
and future structures of transmission lines. In this context, our
research is to investigate new and more efficient techniques in
numerical evaluation and experimental measurement of phase jitter impact
on more general communication systems including dispersion management,
filtering, and spectral inversion schemes.
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