Fig. 3

Super-resolution nanoscopy of the emitter shown in Fig. 1 performed using a single laser and a coincident laser pair as the excitation source. a Schematic of the setup used to perform GSD nanoscopy employing excitation lasers with doughnut-shaped intensity profiles. The system point spread function (PSF) was determined by reflection of the lasers from a 50 nm gold nanosphere (inset, red circle). b Negative GSD images of the single defect under excitation with a single 708 nm, doughnut-shaped laser and using laser powers of 20 mW and 60 mW as indicated. The direct GSD images on the right are obtained by linear deconvolution of the negative GSD images on the left. c Negative GSD images of the same emitter after addition of a 10 µW, 532 nm, doughnut-shaped repumping laser co-aligned with the 708 nm laser. The images on the right are linear deconvolutions of the negative ones. d Photoluminescence intensity profiles of negative GSD in b showing a resolution improvement at higher excitation powers. Solid lines indicate the full-width at half-maximum (i.e., the resolution) of the emission null at the centre of the doughnut. e Intensity profiles used to compare the resolution obtained from negative GSD performed at 40 mW of 708 nm laser using the single doughnut beam (circles, violet) and the co-incident laser pair (triangles, orange). For comparison, the intensity profile obtained from reflection of 50 nm gold nanoparticles (squares, green) is shown as point spread function of our setup. f Dependence of GSD resolution on the power of the 708 nm laser, with and without the co-incident 532 nm, 10 µW repumping laser. Scale bars in b and c are 300 nm. Error bars have been calculated based on repeating the measurement for three times