Fig. 2: Dynamical wave-front shaping.
From: Surface-wave-assisted nonreciprocity in spatio-temporally modulated metasurfaces
a Reflectance measurements for the unmodulated metasurface. b Measured on-demand dynamical beam steering of the n = +1 harmonic. c Calculated spatial distribution of the electric field for on-axis focusing for the \(n = \bar n = + 1\) frequency harmonic (infinite-sized STMM). d Measured power for on-axis focusing. e Calculated (finite-sized STMM, Lx = 19 cm) and measured gain as a function of \(\ell\) for off-axis focusing. Error bars are determined by the standard deviation of gain over a narrow angular range within the focal region. f Measured power for off-axis focusing. In b–f, kin = 0, ωin = 2π × 6.9 GHz and Ω = 2π × 50 kHz. Input power in the experiments is 6.3 mW. Focusing parameters are (xf, zf) = (0,15) cm and (6,15) cm for on-axis and off-axis, respectively.
