We designed a nanoscale light extractor (NLE) for efficient outcoupling and beaming of broadband light emitted by shallow, negatively charged nitrogen-vacancy (NV) centers in bulk diamond. The NLE consists of a patterned silicon layer on diamond and requires no etching of the diamond surface. Our design process is based on adjoint optimization using broadband time-domain simulations and yields structures that are inherently robust to positioning and fabrication errors. Our NLE functions like a transmission antenna for the NV center, enhancing the optical power extracted from an NV center positioned 10 nm below the diamond surface by a factor of more than 35, and beaming the light into a +/-30{\deg} cone in the far field. This approach to light extraction can be readily adapted to other solid-state color centers.
@article{arxiv.2007.04545,
title = {Adjoint-optimized nanoscale light extractor for nitrogen-vacancy centers in diamond},
author = {Raymond A. Wambold and Zhaoning Yu and Yuzhe Xiao and Benjamin Bachman and Gabriel Jaffe and Shimon Kolkowitz and Jennifer T. Choy and Mark A. Eriksson and Robert J. Hamers and Mikhail A. Kats},
journal= {arXiv preprint arXiv:2007.04545},
year = {2020}
}