Abstract

When excitons are created in a dc biased quantum well (QW), excitons are polarized and screen the field. The ultrafast nonlinear optical responses can be expected when the excitons are virtually created by the below-resonance pump pulse.^1,2 This is called virtual charge-induced optical nonlinearity (VCON). The higher order effects, such as two photon absorption,³ hide this effect, thus the direct experimental evidence has not yet been observed. In this paper we examine the VCON process and the ac Stark effect under dc bias field by pump and probe technique with small detuning condition, avoiding the higher order effects.

© 1997 Optical Society of America