L. Wilson

The University of Sheffield, Sheffield, England, United Kingdom

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Publications (2)3.52 Total impact

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    ABSTRACT: We use the Dresden Free-Electron-Laser (FELBE) to investigate intersublevel coherence times in semiconductor quantum dots (QDs) by degenerate four-wave mixing (DFWM) spectroscopy. We know from pump-probe measurements1 on a series of quantum dot samples with varying intersublevel energy that intersublevel relaxation times of the s-p intersublevel transition can become very long (up to 1.5 ns). Due to the discrete nature of these sublevels, intersublevel coherence times should exhibit similar time constants at low temperatures where “pure dephasing” is suppressed.
    Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2013 38th International Conference on; 01/2013
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    ABSTRACT: A multilayer quantum dot sample has been excited with a strong terahertz (THz) electric field and probed with a near-infrared (NIR) laser. First- and second-order THz optical sidebands are generated on the NIR probe beam by driving quantum dot intersublevel resonances with the THz fields. A conversion efficiency of 3×10-6 was obtained for the conversion of NIR power into sideband emission at 4 K, decreasing by a factor of 20 up to room temperature. The sideband emission wavelength can be tuned over ~20 nm by selection of appropriate NIR and THz frequencies, due to the inhomogeneous broadening of the dot ensemble.
    Applied Physics Letters 01/2010; 96:201105. · 3.52 Impact Factor