Fig. 3: Time-resolved PEEM (TR-PEEM) measurements of dielectric waveguide modes.

a Spatiotemporal evolution of waveguide modes measured with TR-PEEM. b Illustration of TR-PEEM measurement. c Crosscut lines from (a) along the red dashed line, indicating wave packet moving with time delay. The dashed pink line in (c) is the visual guide line. d Center of the observed wave packet varies with time delay, the red line is the linear fitting.