Characterisation of ultrashort optical pulses in a dispersion-managed fibre link using two-photon absorption frequency-resolved optical gating

Femtosecond optical pulses of 1550-nm wavelength propagated in a dispersion-managed single-mode optical fibre link consisting of a 50-m dispersion compensation fibre, a 250-m dispersion-shifted fibre, and a 300-m standard dispersion fibre are characterised by high-sensitivity two-photon absorption frequency-resolved optical gating. Output pulse spectrogram shows pulse trailing wings in the short and long wavelength parts of the time-spectral distribution of pulse intensity, and implies dominance of third-order chromatic dispersion in ultrashort pulse propagation in the fibre link. Numerical simulation using a nonlinear pulse propagation equation, including the experimental characteristics of chromatic dispersion in the fibre link, produces a theoretical output pulse shape qualitatively consistent with that of output pulse shape reconstructed from the experimental pulse spectrogram.