Fig. 5

Meta-optics for all-optical modulation. a Left: SEM image of the GaAs metasurface. Right: measured differential reflectance map as a function of the wavelength and delay time. The red and blue colour scales correspond to positive and negative changes, respectively [108]. b Left: SEM image of the plasmonic metasurface. Right: optical density (∆OD) map as a function of the wavelength and delay time. The red and blue colour scales correspond to positive and negative changes, respectively [109]. c Left: SEM image of the ITO metasurface. Right: the dependences of ∆OD on the delay time with different pump fluences [110]. d Left: schematic of transmission modulation from an aluminum-doped zinc oxide metafilm. Right: changes in transmission as a function of the delay time [111]. e Left: schematic of polarization switching from a CdO based metafilm absorber. Right: ∆OD map as a function of the wavelength and delay time. The red and blue colour scales correspond to positive and negative changes, respectively [112]. f Left: schematic of the structure composed of a plasmonic metasurface coupled to an ITO film with an ENZ response. Right: changes in transmission as a function of the pump-probe delay time [113]