Optimized diamond inverted nanocones for enhanced color center to fiber coupling

Nanostructures can be used for boosting the light outcoupling of color centers in diamond; however, fiber coupling performance these nanostructures is rarely investigated. Here, we use a finite element method computing emission from inverted nanocones and overlap this with propagation mode single-mode fiber. Using different figures merit, nanocone parameters are optimized to obtain maximal efficiency, free-space collection or rate enhancement. The designs show promising results 66% 83% efficiency at tin-vacancy center zero-phonon line wavelength 619 nm. Moreover, when evaluated broadband performance, 55% 76% efficiencies respectively, collecting full spectrum room temperature. An analysis fabrication insensitivity indicates that robust against imperfections. For maximum into mode, design Purcell factor 2.34 identified. Finally, possible improvements offered by hybrid nanocone, formed patterning two materials, investigated, increases achievable 71%.