Abstract

Strong resonant excitation of atoms can lead to Mollow spectra in saturation spectroscopy, with gain near the Rabi sidebands or with a coherent dip at the atomic resonance.¹ In this paper we report experimental studies on the manifestation of Mollow spectra and especially gain in an excitonic system. We observe a spectrally sharp coherent excitonic gain in a semiconductor quantum well under strong resonant excitation. Theoretical analysis based on modified optical Bloch equations (MOBE) indicates that this coherent gain differs qualitatively from its counterpart in atomic systems and is a direct result of ex- citon-exciton interactions. Understanding the manifestation of Mollow spectra and gain in an excitonic system provides important insight into coherent optical interactions in semiconductors and is of importance in understanding recently observed parametric gain associated with exci- ton-polaritons in semiconductor microcavities.².

© 2001 Optical Society of America