Abstract

We study the effects of many-particle Coulomb correlations on the ultrafast nonlinear optical response of doped semiconductors with several subbands. In such structures, the Fermi energy of the occupied subband can be close to the excitonic level from the upper subband. In this case, the linear absorption spectrum has a characteristic double-peak form originating from the interference between the Fermi-edge singularity and excitonic resonances.¹ As the electron concentration increases, the two resonances hybridize, with the oscillator strengths shifted towards the Fermi- edge singularity peak.

© 1999 Optical Society of America