Fig. 4. Performance of the nanopillar sensor arrays with direction control.

(A) Histogram of the saturation fluorescence rate (background subtracted) of NV centers. The blue and red bars indicate the data measured with an NA = 0.7 air/dry objective and an NA = 1.42 oil-immersion objective, respectively. (B) Comparison of the simulated and experimental results for different θ (the angle between NV axis and diamond surface) with an NA = 0.7 air/dry objective (blue) and an NA = 1.42 oil-immersion objective (red). The solid line corresponding to the left axis is the result of simulation. The point corresponding to the right axis is the statistical mean of the experimental results, and the error bar is the statistical SD. (C) Laser power–dependent fluorescence count rate measurements for one of the NV centers in (A) by NA = 1.42 oil-immersion objective. The hollow black circles are the photon counting rate data. The bold gray circles are the background count rate data obtained from the value of g⁽²⁾(0), and the gray dashed line is a linear fitting for the background. The bold black circles are the background-subtracted fluorescence rates. The red line is the fitted saturation curve, and the saturation fluorescence rate is 4.34 ± 0.03 Mcps. The inset shows the g⁽²⁾(τ) (measured at an excitation power of ~40 μW). (D) Fluorescence rate as a function of fluorescence-dependent detection sensitivity. Our results are expressed in red (measured with an NA = 1.42 oil-immersion objective) and blue (measured with an NA = 0.7 air/dry objective objective), where the bold circle and solid line are obtained from the experimental data and saturation curve, respectively. The experimental results of NV center photonic structures reported are marked as a reference (7–9, 49).