Group delay dispersion measurements in InGaAsP 1.3-μm optical amplifiers

Group delay dispersion (GDD) of ~15 ps/nm has been measured in a near-traveling-wave optical amplifier at a wavelength where measured gain ripple was ~2 dB, using the envelope phase-shift technique. This is compared to a measured GDD of ~180 ps/nm in a single-facet antireflection-coated amplifier biased below threshold with a gain ripple of ~17 dB. It is shown that these results agree qualitatively with standard theory. An important result is that GDD increases with the square of amplifier length. GDD can be reduced by an order of magnitude if gain ripple is reduced to 0.5 dB