Light-driven lattice reconfiguration for terahertz functional metamaterials.

Surface lattice resonances (SLRs), or lattice modes, support high-Q resonances and significant electromagnetic field enhancement via diffractive coupling, arising from collective Rayleigh scattering in periodically structured metamaterial resonator arrays. However, the spectral characteristics of lattice modes are fixed by structural periodicity, thereby limiting their post-fabrication reconfigurability. Here, we demonstrate light-driven reconfiguration of lattice modes in a terahertz (THz) metamaterial without changing its physical structure. The device comprises a complementary asymmetric split-ring resonator metamaterial integrated with selective photo-active silicon regions. The incident terahertz radiation experiences an effective lattice periodicity that is optically reconfigured from 70 µm towards 140 µm. The pump-induced effect primarily increases the Q-factor of the Fano resonance by reconfiguring its coupling to the lattice mode.