Fig. 4

Dynamic investigation of the plasmonic phyllotaxis-inspired vortex nanosieve. a During the dynamic investigation by TR-PEEM (time-resolved two-photon photoemission electron microscopy), the probe pulse interferes with the propagating SPPs and liberates photoelectrons in a two-photon photoemission process, which will then be imaged with the PEEM setup. b A top-view SEM image of the sample. c–e Raw experimental data of delay-time snapshots from measured TR-PEEM results. Three stages of vortex evolution upon RCP illumination can be identified: formation (c), revolution (d), and decay (e). All the data are shown on a logarithmic intensity scale. f, g Processed images with only SPP dynamics that correspond to the delay times used in (c–e). The small black dashed arrows indicate the propagation of vortex wavefronts in each stage. The black dashed arrows in panel g indicate the revolution direction of the vortex patterns