Correlation-induced resonances in differential absorption of semiconductors

Summary form only given. Extensive recent studies have provided valuable understanding on the role of correlations between excitons in optical interactions in semiconductors. Few experimental and theoretical studies, however, have addressed the effects of correlations when a semiconductor is excited above the band gap. In this paper, we report studies of 4-particle correlations by using differential absorption (DA) at low excitation levels with well-defined initial energies of excited e-h pairs and excitons. We show that these correlations can lead to an induced resonance in DA spectra immediately after excitation of e-h pairs. The origin and dynamics of this correlation-induced resonance (CIR) is discussed.