Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Quantum Dots and Wires: Microcavities

HL 48.2: Vortrag

Mittwoch, 9. März 2016, 09:45–10:00, H15

Experimental and theoretical investigation of a strong optical Stark effect in a semiconductor micropillar cavity — •Fabian Hargart¹, Kaushik Roy-Choudhury², Tilmann John¹, Simone Luca Portalupi¹, Christian Schneider³, Sven Höfling³, Martin Kamp³, Stephen Hughes², and Peter Michler¹ — ¹Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart, Allmandring 3, 70569 Stuttgart — ²Department of Physics, Engineering Physics and Astronomy, Queen’s University, Kingston, Ontario, Canada K7L 3N6 — ³Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg

The energy shift of a two-level system by intense, oscillating electric fields—commonly known as AC Stark shift—is studied experimentally and theoretically for a cavity-driven, detuned quantum dot-cavity system. The electric field enhancement inside the cavity facilitates exceptionally strong line shifts of up to 4 µ eV/µ W. The effect is systematically investigated in dependence of the driving Rabi frequency Ω and the QD-cavity detuning δ. The fine structure splitting of exciton states |X> and |Y> can be increased by magnitudes of orders due to their unequal QD-cavity coupling strengths g_X and g_Y. By extending the system to four levels, including also the biexciton state, we explain the observation of an unexpected opposite Stark shift within a dressed-state picture. The experimental results are reproduced using a simple Hamiltonian for the QD-cavity system and the driving laser field.