Ultrafast polarization dynamics in optically excited biased quantum wells

Dmitry Turchinovich, Boris S. Monozon, Martin Koch, Sandra Lahmann, Uwe Rossow, Andreas Hangleiter, Peter Uhd Jepsen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearch


We observe ultrafast polarization dynamics in strongly internally biased InGaN/GaN multiple quantum wells during intense femtosecond optical excitation by means of time-resolved detection of THz emission, correlated with time-integrated photoluminescence measurements. We demonstrate that in the case of strong enough excitation the built-in bias field (on the order of MV/cm) can be completely screened by the carriers excited into spatially separated states. This ultrafast screening of the initial bias field across the quantum well leads to dynamical modification of the band structure of the sample, and consequently to dynamical modification of the optical absorption coefficient within the duration of the excitation pulse. We show that such an optically induced dynamical screening of the biased quantum well can be described in terms of discharging of a nano-scale capacitor with a femtosecond laser pulse. The electrostatic energy stored in the capacitor is released via THz emission. A realistic quantum-mechanical model of the temporal evolution of the polarization inside the quantum wells shows that due to its nonlinearity such a process may lead to emission of a THz pulse with bandwidth significantly exceeding that of the excitation pulse.
Original languageEnglish
Title of host publicationProceedings of SPIE
Publication date2004
Publication statusPublished - 2004
Externally publishedYes
EventTerahertz and Gigahertz Electronics and Photonics III - San Jose, CA, USA
Duration: 1 Jan 2004 → …


ConferenceTerahertz and Gigahertz Electronics and Photonics III
CitySan Jose, CA, USA
Period01/01/2004 → …


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