The carrier dynamics in an InGaAsP quantum-well laser amplifier excite
d by an ultrashort optical pulse is investigated experimentally as wel
l as theoretically. For operation in the absorption region, a transiti
on from pump induced cooling to pump induced heating of the carriers i
s observed for increasing pump pulse energy and is attributed to the g
eneration of hot carriers through two-photon absorption. The results f
urther support the interpretation of the carrier dynamics in the pertu
rbative regime.