Figure 2.

Working principle and experimental results of dynamic holography. (a) Schematic diagrams of light propagation in the metasurface device before and after hydrogenation. (b) Simulated reflectance spectra and phase delay with incident light at the wavelength of 633 nm at the Mg (black) and MgH₂ (red) states. (c) Phase distribution for the hologram of a musical note. (d) SEM images of the metasurface sample. (e) Experimentally recorded switchable hologram through hydrogenation (H₂) and dehydrogenation (O₂).