Enhancing the efficiency of quantum-dot-based single-photon source designs by suppressing background emission using concentric rings

In this paper, we theoretically demonstrate that a few-period circular Bragg reflector consisting of concentric rings placed around an infinite nanowire with an embedded quantum dot of unity quantum efficiency can increase the fraction of radiative emission into the fundamental \(\textrm{HE}_{11}\) mode ( \(\beta =\Gamma _{\textrm{HE}_{11}}/\Gamma _\textrm{Total}\) ) up to 0.999 due to enhanced suppression of the emission into radiation modes caused by a photonic bandgap effect. We then apply this strategy in the practically relevant case of the finite-sized single-photon source based on tapered nanowires and demonstrate that the collection efficiency can be improved. Additionally, we also show the beneficial effects of placing optimized rings around the micropillar single-photon source.