Power transients arising from cross-saturation in erbium-doped fibre a
mplifiers (EDFAs) are generally thought to be slower than 100 mu s due
to the slow gain dynamics. This is a key advantage of EDFAs. The auth
ors report on power transients of 1dB in <3 mu s in a chain of five ED
FAs. These fast power variations result from the collective behaviour
of the amplifier chain.