Fig. 4: Proof-of-principle demonstrations of sub-diffraction all-optical switching.

a The final magnetization state induced by a single pulse. b The final magnetization states induced by a pair of spatially offset and time-delayed dual pulses with ∆t = a few seconds and ∆t = 500 ps. The solid and dashed circles indicate the irradiation areas of the first and second pulses, respectively. c, d The one-dimensional sub-diffraction all-optical switching array recorded through the dual-shot method (∆t = 500 ps) by sweeping the dual pulses from the right side to the left side of the sample (c) or vice versa (d). The red arrows indicate the sweeping directions. The scale bar is 40 μm