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.