Ultrafast Vectorial Currents in Nanoscale Symmetry-Controlled Optoelectronic Metasurfaces*

Controlled charge flow underpins nearly all modern information technologies, while ultrafast vectorial nanoscale currents provide new opportunities in high-frequency nanoelectronics, transient symmetry control, nano-magnetism, electron hydrodynamics, and terahertz science. Clearly, the conventional paradigms of integrated circuits are limited in terms of versatility, speed, and active control, while emerging optoelectronic paradigms remain limited in terms of scalability and complex light-matter interaction configurations. Here we demonstrate a new class of optoelectronic metasurfaces that overcome many of these challenges by combining nanoscale patterning with a high degree of active optical control. Nanoplasmonic excitations of symmetry-broken gold antennas serve to drive directional photothermoelectric currents in underlying graphene monolayers, with local (unit cell) symmetries designed for versatile optical responses and corresponding local and global (millimeter-scale) current distributions. Polarization- and frequency-dependent optical responses for different unit cell symmetries offer direct sensitivity to these optical parameters in integrated graphene photodetection applications. Intriguingly, despite the relatively low-quality, large-area graphene utilized here, simulations suggest a new regime of ultrafast-induced electron hydrodynamic behaviors and nanoscale vortical flows. These results suggest additional and more general opportunities for designer control over ultrafast, nanoscale vectorial charge flow in a variety of applications and hybrid systems.