Fig. 1. Device structure and process flow. (a) Process flow and schematics of the two hybrid α-Si/VO2 metasurfaces with VO2 at the bottom and center of the α-Si nanodisks. SEM images of the (b) HMB and (c) HMM devices. Inset shows the top-view SEM image.

Fig. 2. Tunable optical properties of HMB and HMM configurations. (a) Simulated and (b) measured transmittance spectra of the HMB configuration at dielectric and metallic states. (c) Simulated and (d) measured transmittance spectra of HMM configuration at dielectric and metallic states. Simulated transmission phase spectra of (e) HMB and (f) HMM configurations at dielectric and metallic states.

Fig. 3. Modal profiles of the HMB and HMM devices at ED and MD wavelengths, for both the dielectric state (D state) and the metallic state (M state). (a) Electric field distributions of ED mode at the dielectric state (left) and the metallic state (right) for the HMB device. (b) Electric field distributions of MD mode at the dielectric state (left) and the metallic state (right) for the HMB device. (c) Electric field distributions of the ED mode for the dielectric state (left) and the metallic state (right) of the HMM device. (d) Electric field distributions of MD mode for the dielectric state (left) and the metallic state (right) of the HMM device.

Fig. 4. Multipolar decomposition of the scattering cross sections. Scattering cross-section spectra of ED and MD modes of (a) HMB and (b) HMM configurations at the dielectric and metallic states. Simulated and fitted transmission spectra of (c) HMB and (d) HMM configurations for different metallic fractions of VO2.