Simultaneous Control of the Spatial and Temporal Spectra of Light With Space-Time Varying Metasurfaces

This paper presents space-time varying (STV) metasurfaces for simultaneously controlling the spatial and temporal spectra of electromagnetic waves. These metasurfaces transform incident electromagnetic waves into specified reflected and transmitted waves, with arbitrary temporal and spatial frequencies. They are synthesized in terms of time-domain generalized sheet transition conditions. Moreover, they are characterized using an analytical method and the unstaggered finite-difference time-domain technique adapted to space-time metasurfaces. STV metasurfaces performing pulse shaping, time reversal, and differentiation are demonstrated as examples.