Figure 3.

GST-based metasurface with a grating nanostructure. (a) Tilted incidence and (b) cross-sectional SEM image of the nanograting in a GST₂₂₅ film on an SiO₂ layer; (c) Simulated spreading of y-component of the electric field in the xz surface for a nanograting unit cell at resonance; (d) Reflection and transmission spectra of the nanograting based on GST₂₂₅ at both amorphous and crystalline phases. Calculated switching contrast of (e) reflection and (f) transmission dispersion of the TE mode at both of the GST₂₂₅ phases; (g) Schematic illustration of the GST-based absorber-modulator using gratings for near infrared spectra; (h) The simulated reflectance curve with strips of Au top electrode and GST₂₂₅ thin film in both recognized phases; (i) The optimized extinction ratio (ER) for the maximum modulation depth (MD = 77%) at 1550 nm. (a–f) are adapted from [1], with permission from © 2016 AIP Publishing LLC; and (g–i) are adapted from [38], with permission from © 2016 OSA. ER is described by the logarithm of the reflected power ratio, while MD represents the difference between the maximum and minimum reflected power.