Hybrid Plasmonic Photonic Crystal Cavity for Enhancing Emission from near-Surface Nitrogen Vacancy Centers in Diamond

Optical cavities create regions of high field intensity, which can be used for selective spectral enhancement of emitters such as the nitrogen vacancy center (NV) in diamond. This report discusses a hybrid metal–diamond photonic crystal cavity, which provides greater localization of the electric field than dielectric cavities and mitigates metal-related losses in existing plasmonic structures. We fabricated such hybrid structures using silver and single-crystal diamond and observed emission enhancement of NVs near the diamond surface. We measured a mode quality factor (Q) as high as 170 with a simulated mode volume of ∼0.1 (λ/n)3 and demonstrated its tunability. This cavity design and the associated fabrication approach specifically target enhancement of emission from near-surface NVs.