Fig. 7

Tunable metasurface holography and nonlinear metasurface holography. a Schematic of the demonstrated switchable photonic SOIs. Different optical performances of three designed metadevices can be switched when the GST layer is in amorphous or crystalline states. SEM images of fabricated patch antennas array are shown on the left bottom corner. The experimental results are shown on the right bottom corner [94]. b Schematic of a metasurface hologram on a stretchable substrate. The sizes and locations of holographic images can be changed by stretching the substrate [95]. c Merged metasurfaces composed of two independent phase profiles containing Mg/Pd and Au nanorods as dynamic and static pixels, respectively. The representative snapshots of the holographic images harmony and peace during hydrogenation and dehydrogenation are shown on the bottom [96]. d All-dielectric metasurfaces composed of C-shaped Si nanoantennas for nonlinear holography at THG [100]. e Silicon metasurfaces for nonlinear wavefront control of the third-harmonic generation and multiplexed holography. The generated nonlinear signal acquires phase modulations of θ_co = 2σϕ and θ_cross = 4σϕ in co- and cross-polarization states controlled by the oreientation angle, respectively. The experimental results of multiplexed holography are shown on the right [101]