Subvolt high-speed free-space modulator with electro-optic metasurface

Active metasurfaces incorporating electro-optic materials enable high-speed free-space optical modulators that show great promise for a wide range of applications, including optical communication, sensing and computing. However, the limited light-matter interaction lengths in metasurfaces typically require high driving voltages exceeding tens of volts to achieve satisfactory modulation. Here we present low-voltage, high-speed free-space optical modulators based on silicon-organic-hybrid metasurfaces with dimerized-grating-based nanostructures. By exploiting a high-Q resonant mode, normally incident light is effectively trapped within a submicrometre-scale silicon slot region embedded with organic electro-optic material. Consequently, highly efficient modulation is obtained, enabling data transmission at 50 Mbps and 1.6 Gbps with driving voltages of only 0.2 V and 1 V, respectively. These metasurface modulators can now operate at complementary metal-oxide-semiconductor-compatible voltage levels, allowing energy-efficient high-speed practical applications of active metasurfaces.