Dynamics of excitons in individual InAs quantum dots revealed in four-wave mixing spectroscopy
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A detailed understanding of the population and coherence dynamics in optically driven individual emitters in solids and their signatures in ultrafast nonlinear-optical signals is of prime importance for their applications in future quantum and optical technologies. In a combined experimental and theoretical study on exciton complexes in single semiconductor quantum dots we reveal a detailed picture of the dynamics employing three-beam polarization-resolved four-wave mixing (FWM) micro-spectroscopy. The oscillatory dynamics of the FWM signals in the exciton-biexciton system is governed by the fine-structure splitting and the biexciton binding energy in an excellent quantitative agreement between measurement and analytical description. The analysis of the excitation conditions exhibits a dependence of the dynamics on the specific choice of polarization configuration, pulse areas and temporal ordering of driving fields. The interplay between the transitions in the four-level exciton system leads to rich evolution of coherence and population. Using two-dimensional FWM spectroscopy we elucidate the exciton-biexciton coupling and identify neutral and charged exciton complexes in a single quantum dot. Our investigations thus clearly reveal that FWM spectroscopy is a powerful tool to characterize spectral and dynamical properties of single quantum structures.
Mermillod , Q , Wigger , D , Delmonte , V , Reiter , D E , Schneider , C , Kamp , M , Höfling , S , Langbein , W , Kuhn , T , Nogues , G & Kasprzak , J 2016 , ' Dynamics of excitons in individual InAs quantum dots revealed in four-wave mixing spectroscopy ' Optica , vol. 3 , no. 4 , pp. 377-384 . DOI: 10.1364/OPTICA.3.000377
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DescriptionWe acknowledge the support by the ERC Starting Grant PICSEN, contract no. 306387. D.E.R. is grateful for financial support from the DAAD within the P.R.I.M.E. program.
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