Optimized designs for micropillar cavity with simultaneously high quality factor and Gaussian far field at near-wavelength diameter

Micropillar cavities with small volumes and high quality factors (Q-factor) greatly enhance the light-matter interaction. Crucially, these cavities exhibit a near-Gaussian far-field pattern, making them highly suitable for efficiently coupling and manipulation of emitted photons. However, their miniaturization into near-wavelength scales is limited by diffraction, resulting in both Q-factor degradation and far-field emission divergence. Here, we propose a tapered micropillar cavity design that simultaneously achieves a high Q-factor (Q = 1.37 × 10