Numerical modeling of the coupling efficiency of single quantum emitters in photonic-crystal waveguides

Planar photonic nanostructures have recently attracted a great deal of attention for quantum optics applications. In this paper, we carry out full 3D numerical simulations to fully account for all radiation channels and thereby quantify the coupling efficiency of a quantum emitter embedded in a photonic-crystal waveguide. We determine the leakage from the quantum emitter to the surrounding environment and study its spectral and spatial dependence. The spatial maps of the coupling efficiency, the β factor, reveal that even for moderately slow light, a near-unity β factor is achievable and is remarkably robust to the position of the emitter in the waveguide.