A cavity-based optical antenna for color centers in diamond

An efficient atom-photon interface is a key requirement for the integration of solid-state emitters, such as color centers in diamond, into quantum technology applications. As other solid-state emitters, however, their emission into free space is severely limited due to the high refractive index of the bulk host crystal. In this work, we present a planar optical antenna based on two silver mirrors coated on a thin single crystal diamond membrane, forming a planar Fabry-Perot cavity that improves the photon extraction from single tin vacancy (SnV) centers and their coupling to an excitation laser. Upon numerical optimization of the structure, we find theoretical enhancements in the collectible photon rate by a factor of 60 as compared to the bulk case. As a proof-of-principle demonstration, we fabricate single crystal diamond membranes with sub-mu m thickness and create SnV centers by ion implantation. Employing off-resonant excitation, we show a sixfold enhancement of the collectible photon rate, yielding up to half a million photons per second from a single SnV center. At the same time, we observe a significant reduction of the required excitation power in accordance with theory, demonstrating the functionality of the cavity as an optical antenna. Due to its planar design, the antenna simultaneously provides similar enhancements for a large number of emitters inside the membrane. Furthermore, the monolithic structure provides high mechanical stability and straightforwardly enables operation under cryogenic conditions as required in most spin-photon interface implementations.

Automated summary

An efficient planar optical antenna based on silver mirrors coated on a thin single crystal diamond membrane has been proposed to improve photon extraction from single tin vacancy (SnV) centers and their coupling to an excitation laser. Numerical optimization shows a theoretical enhancement in the collectible photon rate by a factor of 60 compared to the bulk case. Experimental results demonstrate a significant reduction in the required excitation power and high mechanical stability of the structure, showcasing its functionality as an optical antenna for a large number of emitters inside the membrane.