Figure 7.

Nonlinear harmonic manipulations via TDC digital metasurfaces. (a) Conceptual illustration of TDC digital metasurfaces for spectral manipulations. Reproduced from [109]. (b) Geometry of the varactor-based programmable metasurface and its element. Reproduced from [109]. (c) The calculated spectral intensities pertaining to phase modulation waveforms with 1-bit (“010101…”) and 2-bit (“00-01-10-11…”) time-coding sequences. Reproduced from [109]. (d) Conceptual illustration of TDC digital metasurfaces for independent manipulation of harmonic phases and amplitudes. Reproduced from [120]. (e) Measured spectral phases and amplitudes at various harmonics, corresponding to three different voltage combinations V₁/V₂. Reproduced from [120]. (f) Measured scattering patterns at the +1^st harmonic frequency, corresponding to three sets of spatial coding “00000000,” “00001111,” and “00110011,” respectively. Reproduced from [120].