Abstract

Multiple quantum wells (MQW) exhibit high resonant optical nonlinearities caused by the quantum confinement of carriers. Here we investigate the ultrafast thermalization dynamics of optically excited excitons in an InGaAsP/InGaAsP MQW laser structure for 1.55 μm by means of femtosecond pump/probe spectroscopy. We observe an ionization of the cold excitons by absorption of thermally activated longitudinal optical (LO)-phonons within 180 fs at room temperature comparable to results obtained in GaAs/AlGaAs MQW. [1]. The time constant of this ionization increases with decreasing lattice temperature due to the decreasing thermal population of LO-phonons described by Bose-Einstein statistics.

© 1998 IEEE