Thesis presented December 20, 2023

Abstract:
Semiconductor microcavities constitute a major workhorse for quantum photonics. Quantum cavity effects such as the enhancement of the spontaneous emission rate of embedded artificial atoms (known as Purcell effect) are already harnessed in efficient single photon sources. Additionally, the ultrafast tuning of cavity properties through the injection of charge carriers has opened appealing novel perspectives, such as the adiabatic frequency translation of trapped light, or the dynamic control of emitter-cavity detuning and cavity effects. In this work, we investigate some dynamic properties of cavities and coupled cavity-quantum dot systems with resolution on the few picoseconds time scale. We perform cavity-ring down experiments on planar GaAs/AlAs cavities and confirm that very large quality factors Q around 300000 can be obtained using an original design involving a very large spacer layer. We also highlight the detrimental effect of lateral thickness gradients, which lead to a non-exponential relaxation of the cavity mode. We bring also new light on the free-carrier switching of pillar microcavities. Using a focused pump beam, we observe much different specific behaviors for various modes and reveal a transient crossing of two sets of modes when the perturbation preserves the cylindrical symmetry of the cavity. Finally, we explore the transient coupling of a switched cavity mode with quantum dots and investigate the experimental signatures of this “on-off” switching of the Purcell effect, including the generation of few picoseconds-long pulses of spontaneous emission. We discuss the medium-long term impact of this work in the field of quantum photonics.

Keywords:
Single photon source, spontaneous emission, Purcell effect, optical microcavity, cavity switching