Figure 4: Coupled emission of a single NV centre to CPPs in a VG.

(a–e) Wide-field collection fluorescence microscopy images of an assembled NV–VG device. (a) On wide-field illumination the contour of the VG can be detected owing to the enhancement of the Au auto-fluorescence at the VG location. (b–c) Collection polarization (red arrow) set transversal to the VG axis evidences the guided emission out-coupled from the VG tapered mirrors. Additional out-couplers along the VG axis correspond likely to defects in the VG. The excitation polarization (green arrow) was set transversal (b) and parallel (c) to the VG axis, respectively. (d–e) Collection polarization set parallel to the VG axis. Only emission coming directly from the excited NV centre is observed for both parallel (d) and transversal (e) excitation polarizations. (f) Fluorescence intensity along the dashed line in (b–e) (same colour code as the frames). (g) Lifetime measurements for the polarization configuration of (c) at three different collection locations. Direct collection (black) and emission out-coupled from the left (magenta) and right (cyan) VG extremities. Similar lifetime values measured at the three positions confirm that the guided emission corresponds to that of the single NV centre coupling to CPPs.