This work is focused on the optical properties of electrically pumped vertical-cavity surface-emitting structures which use self-assembled quantum dots (QDs) as an active medium. In order to investigate the electric field propagation and the carrier dynamics, we have proposed a model which is based on the self-consistent quantum dot-wetting layer Maxwell-Bloch equations incorporating microscopically calculated Coulomb and phonon-assisted scattering processes between the QD and the QD-embedding WL states. The scattering rates are calculated within a second order screened Born-Markov approximation and implemented as a function of the wetting layer carrier density. All numerical calculations for the carrier dynamics and the field propagation are performed using the finite-difference time-domain (FDTD) method for the full structure. Within this model, the normal mode coupling in the weak and strong coupling regime as well as the linear and nonlinear regime are studied on a microscopic level in dependence on the structural parameters, the QD properties, and the properties of the input pulse at the temperatures of 77 K and 300 K. A more detailed understanding of the light-matter interaction in the normal mode coupling is provided by the time dynamics of the electric field, the QD population inversion, and the scattering rates as well as the transmission spectra. Furthermore, the switch-on dynamics of QD vertical-cavity surface-emitting lasers (VCSELs) is microscopically investigated since the internal time scales of the switch-on delay time and the frequency and damping of relaxation oscillations of the lasers are important for high-speed optical systems. The obtained internal time scales in dependence on the strength of the injection current, the Bragg mirror reflectivity, and the number of QD layers are in agreement with experimental data. Summarizing, the work presented in this thesis provides a microscopic understanding of the light-matter interaction in confined nanostructures and further insight into other advanced techniques such as current modulation and modelocking.
|School:||Technische Universitaet Berlin (Germany)|
|Source:||DAI-C 81/1(E), Dissertation Abstracts International|
|Subjects:||Optics, Electrical engineering, Condensed matter physics|
|Keywords:||Self-assembled quantum dots|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be