Figure 5.

Inhomogeneous tunable metasurfaces. (a) A tunable metadevice formed by meta-atoms incorporated with photosensitive materials to achieve light-controllable reflections on incident microwaves. Inset: picture of the fabricated sample. (b) Aberration-free and functionality-switchable microwave metalenses with individual meta-atoms controlled with different applied bias voltages. (c) A microwave coding-metasurface achieving reprogrammable holograms controlled by voltages applied on PIN diodes embedded in constitutional meta-atoms. (d) A microwave tunable flat lens realized with random-access reconfigurable metamaterial based on microfluidic technology. Insets: picture and schematics of the microcavity filled with liquid metal. (e) Schematics of the single-pixel imaging process realized with a THz Spatial light modulator (SLM). Insets: photo of the fabricated SLM and measured absorption spectra of a single pixel under two bias voltages. (f) Gate-controlled diffractions of light at a MIM metadevice with ITO as its spacer, under appropriately chosen electric gating. (g) An adaptive metalens formed by dielectric metalens and artificial muscles to realize simultaneous controls on focal length, astigmatism, and shift of the formed image, enabled through electrical-strain control on the artificial muscles. Reproduced with permissions: (a) from [47] © 2012 APS; (b) from [48] © 2016 AIP. (c) from [49]; (d) from [50] © 2015 WILEY-VCH; (e) from [51] © 2014 Macmillan Publishers Limited; (f) from [52] ©2016 ACS; (g) from [53].