Abstract

The dephasing (loss of coherence) of excitons in semiconductors and semiconductor quantum wells (QWs) at low temperatures is governed by collisions with residual acoustic phonons and impurities and, at elevated densities, by exciton-exciton and exciton free-carrier scattering. The resulting dephasing times in GaAs were found to be ~7 ps.¹ We study the exciton dephasing process in high quality MBE InGaAs/InAlAs QWs grown on InP in a time-resolved degenerate four-wave mixing experiment. Our source is a YLF:Nd pumped, additive pulse mode-locked (APM) color center laser, delivering 140-fs pulses, tunable around 1500 nm, similar to that in Ref. 2.

© 1990 Optical Society of America