Numerical Investigation of a Coupled Micropillar - Waveguide System for Integrated Quantum Photonic Circuits

The on-chip resonant excitation of single quantum dots (QDs) via integrated microlasers represents an effective and scalable method for integrated quantum photonics applications based on on-demand single-photon emitters. In this study, the design and numerical optimization of the evanescent coupling between whispering gallery modes (WGMs) of a micropillar resonator and a nearby single-mode ridge waveguide in the Al(Ga)As/GaAs material system are presented. In this study, such systems are examined within a wavelength range of 930 nm, which is suitable for resonant excitation of typical self-assembled InGaAs quantum dots. In particular, the coupling and the transmitted optical power of a WGM resonator to a ridge waveguide are examined for a range of gap spacings, with the objective of optimizing the photon coupling efficiency and Q-factor of the monolithically integrated nanophotonic system. The findings of this study enable to identify the best device parameters for subsequent device fabrication. The findings establish a foundation for the production of highly effective photonic quantum circuits through the use of WGM microlasers integrated into evanescently coupled waveguide systems, including resonantly excited single quantum dots. In this work, the conceptual device of a whispering gallery mode micropillar coupled to a ridge waveguide is presented for the subsequent realization of the on-demand and on-chip resonant excitation of waveguide integrated quantum dots. The finite element method is then used to precisely characterize the quality factor and the coupling efficiency of such a device for different geometry parameters. image