Evaluation of the coupling efficiency of large-diameter nanofiber Bragg cavities

We analyze the coupling efficiency of a single dipole with a nanofiber Bragg cavity (NFBC) for single photon sources. Conventionally, NFBC diameters are set at approximately half of the emission wavelength to maximize coupling efficiency, but these thin structures are fragile at low temperatures. By employing three-dimensional finite difference time domain simulations, we investigate NFBCs with diameters ranging from 450 to 600 nm, which offer more mechanical robustness. Our results show that NFBCs with diameters of 450 and 500 nm achieve coupling efficiencies exceeding 80%. This study paves the way for practical single-photon sources with enhanced mechanical stability, which is crucial for applications in quantum networks and quantum computing.