Theory of the excitonic Mollow spectrum in semiconductors

Rong-Chun Ge, S. Weiler, A. Ulhaq +4 more

Charge-neutral excitons in semiconductor quantum dots (QDs) have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, namely a Mollow quintuplet under general excitation conditions. We experimentally confirm such spectral quintuplets for In(Ga)As QDs and obtain very good agreement with theory.

Tohya Hiroshima

Rong-Chun Ge, Stefanie Weiler, Ata Ulhaq +4 more

Charge-neutral excitons in semiconductor quantum dots (QDs) have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, namely a Mollow quintuplet under general excitation conditions. We experimentally confirm such spectral quintuplets for In(Ga)As QDs and obtain very good agreement with theory.

Takashi Kuroda

Михаил Михайлович Глазов, Robert A. Suris

Mark C. Phillips, Hailin Wang

Summary form only given. 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. 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 exciton-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 exciton-polaritons in semiconductor microcavities.