Figure 2:

Experimental comparison of NV spectra under plasmonic influence. (A) Polar contour plot of NV emission intensities for the setup in Figure 1(B), in the presence of a gold nanoparticle of radius r _m = 30 nm located at R = 38 nm from the NV center in air. (B) NV Emission intensity spectrum of the same NV-MNP setup obtained at θ = π/2 radians. The solid purple line shows the total NV emission and the long-dashed purple line shows the approximate far-field NV emission accounting for the MNP induced nonradiative losses of the emitted photons. The latter is obtained by scaling the total NV emission by the quantum efficiency (QE) ∼0.78 reported for the setup in [3], which assumes a QE $\sim 0.99$ for the bare NV center. Dotted curve depicts the spectrum of the isolated NV center magnified six times. (C) Modified decay rate spectrum (red curve) for a generic emitter oriented perpendicular to the aforementioned MNP surface, normalized by the respective free-space emission rate γ ^f (ω). Red circles capture the normalized decay rates for NV^⊥MNP (θ = π/2) case for the NV emission band peaks. The dashed blue curve depicts the absolute polarizability of the MNP, and its value at the input laser frequency (532 nm wavelength) is marked with the blue diamond. (D) Comparison of the calculated ZPL and integrated emission intensities against the experimentally detected photon counts in [3]. All emission values are normalized by the area of the isolated NV center spectrum at θ = π/2.