Ultrafast Coherent Exciton Spectroscopy and Carrier Control in Quantum Structures

Abstract

Interference effects between ultrafast laser pulses become important when the relative phase is precisely determined. The response of an optical system then shows strong oscillations when the pump-pulse separation is changed.^1–4 These oscillations appear even for non-overlap** pulses as long as the phase relaxation time of the optical transition exceeds the pump-pulse separation. This interference spectroscopy, in contrast to other coherent optical techniques,⁵ gives direct access to the phase evolution in time, which is especially interesting in semiconductors because many-body interactions cause distinct departures from expected behavior of ideal two-level systems.^{6, 7}