A. C. Klettke

Systematic investigation of terahertz-induced excitonic Rabi splitting

Faculty of Physics and Material Sciences Center,Philipps University, Renthof 5, 35032 Marburg, Germany(Dated: May 31, 2013)Weak near-infrared and strong terahertz excitation are applied to study excitonic Rabi split-ting in (GaIn)As/GaAs quantum wells. Pronounced anticrossing behavior of the split peaks isobserved for different terahertz intensities and detunings relative to the intraexcitonic heavy-hole1s-2p-transition. At intermediate to high electric fields the splitting becomes highly asymmetric andexhibits significant broadening. A fully microscopic theory is needed to explain the experimentalresults. Comparisons with a two-level model reveal the increasing importance of higher excitonicstates at elevated excitation levels.I. INTRODUCTION

Direct measurement of light–matter energy exchange inside a microcavity

We demonstrate that one can directly measure the time evolution of light–matter interaction in a semiconductor microcavity by tracking how the optical response is changed by strong single-cycle terahertz (THz) pulses. A short THz pulse transiently interrupts the interaction of the quantum-well microcavity with the light mode and resets the polaritonic light–matter oscillations at THz frequencies. This THz-reset protocol can provide novel insights into the light–matter coupling dynamics in a wide range of photonic materials such as plasmonic and organic systems.

Controlling the polarization dynamics by strong THz fields in photoexcited germanium quantum wells

The interaction of strong single-cycle THz pulses with the optically induced polarization in germanium quantum wells is studied. With increasing THz field strength, it is observed that the excitonic resonances shift toward higher energy and broaden before weak signatures of a splitting of the exciton line occur. In comparison with high-quality GaAs-based quantum wells, where a much clearer Autler–Townes splitting is observed, the germanium system response is significantly more broadened and shows signatures of a quasi-steady-state behavior due to the intrinsic fast dephasing times dominated by intervalley scattering.

Terahertz Excitation of Three-level Λ-Type Exciton-Polariton Modes in Quantum-Well Microcavity

Interactions of strong few-cycle THz pulses with the induced optical polarization in a quantum-well microcavity reveal that the exciton-polariton modes and the 2p-exciton state form a unique Λ-type three-level system of the coupled light-matter modes.