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https://hdl.handle.net/2142/20652
Description
Title
Modelling of quantum well electrooptical devices
Author(s)
Mares, Peter John
Issue Date
1992
Doctoral Committee Chair(s)
Chuang, Shun-Lien
Department of Study
Electrical and Computer Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Physics, Condensed Matter
Physics, Optics
Language
eng
Abstract
Due to the technological importance of quantum well electrooptical modulators in general and, in particular, as building blocks of self-electrooptic effect devices (SEEDs), in this thesis, we have undertaken to create a theoretical model which can accurately emulate and predict, starting from basic principles, the behavior of quantum well modulators and SEEDs. Although many authors have investigated various aspects of the physics of quantum well structures, to the best of our knowledge, this is the first attempt to obtain a match between theory and experiment for the electronic properties, the optical properties and the input power versus output power (input/output) characteristic of interband SEEDs based on a consistent set of experimental data with the linewidth as the only fitted parameter.
First, the theoretical model which is used to compute the electronic properties, the optical properties, and the input/output characteristic of SEEDs is outlined. It includes excitonic effects, and the absorption coefficient is based on the density matrix formalism. The AlGaAs/GaAs system and also the technologically important InGaAs/InP system are examined. Excellent agreement is obtained between our theoretically generated results and the experimental data found in the literature not only for the electronic and the optical properties but also for the input/output characteristic.
"Next, the feasibility of SEED operation at a wavelength of 10 $\mu$m, based on intersubband transitions in coupled quantum wells (CQWs), is theoretically demonstrated. In an attempt to improve the input/output characteristic, a ""symmetric-like"" SEED configuration is explored. The primary device is based on the (2-3) transition of a CQW while the load device utilizes the (1-3) transition of a CQW."
Finally, a symmetric CQW structure is engineered such that it is possible, at F $>$ 0, to merge, at the same transition energy, the C1-HH2 and the C2-HH1 exciton peaks and similarly the C1-LH2 and the C2-LH1 exciton peaks. Consequently, the application of a moderate electric field results in a significant enhancement of the TE and TM absorption coefficients. The anticrossing behavior of the HH2 and HH3 eigenvalues and the effect that this has on the absorption spectrum are also examined.
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