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978-3-8439-0156-7, Reihe Physik
Resonance Fluorescence and Stimulated Light Emission from Coupled Semiconductor Quantum Dot - Cavity Systems
172 Seiten, Dissertation Universität Stuttgart (2011), Softcover, A5
Self-assembled semiconductor quantum dots (QDs) embedded in low volume/high quality optical microcavities are ideal solid-state systems for several applications due to their unique properties, e.g., discretized energy levels. While a single QD is an efficient single and entangled photon source for applications in quantum information technologies, an ensemble of QDs is used as an active material for low threshold microcavity lasers.
In the first part, stimulated light emission from ensemble of QDs is presented. We report on complementary experiment-theory investigations regarding the photon statistics and coherence properties of quantum dot-based semiconductor micropillar lasers with high β factors, i.e., a large coupling of spontaneous emission into the lasing mode. Our results reveal that the measure of correlation functions is an important tool to identify the lasing threshold for high beta lasers.
In the second part, resonance fluorescence from a single QD in a high-Q microcavity is presented. Using an orthogonal excitation /detection geometry enabled a strong suppression of the resonant driving and led the detection of resonance fluorescence from a single QD. Pump-power dependent PL measurements were performed and close to Fourier-transform limited single photon generation was demonstrated in the low power limit. Increasing the excitation power revealed the evolution of Mollow triplets in the emission spectrum with Rabi splitting up to 60 $\mu$eV. In addition, the coherence properties of resonance fluorescence of a single QD were investigated via two-photon interference experiments, and a record visibility of 90% was achieved, thus reflecting a high degree of post-selective indistinguishability.
In the last part, systematic investigations on a non-resonantly coupled QD-cavity system are presented. Temperature dependent $\mu$-PL measurements on a quasi-resonantly excited single QD showed an unambiguous role of phonon-related pure dephasing processes on the non-resonant coupling mechanism. In addition, decay dynamics of a single QD was also measured as a function of detuning and a factor of 16 Purcell enhancement was observed in the spontaneous emission rate of the QD. Finally, the detuned cavity mode emission was utilized to monitor important s-shell properties of a single QD such as homogeneous linewidth, emission saturation and photon statistics with a background free signal at the cavity mode frequency.