Optoelectronic Metasurfaces

Metasurfaces constructed from metallic nanostructures can be designed to operate efficiently as coupling structures for incident optical beams to surface plasmon polaritons (SPPs) propagating thereon. On a semiconductor, metallic metasurfaces can act simultaneously as a device electrode while ensuring strong optical field overlap with the active region. Additionally, SPP fields thereon can be confined to sub-wavelength dimensions and significantly enhanced relative to the exciting field. These features are very attractive for nanoscale optoelectronic device applications, such as photodetectors and modulators. We discuss recent progress on optoelectronic metasurfaces, particularly recent device demonstrations for high-speed reflection modulators based on a metal-oxide-semiconductor capacitor structure exploiting the carrier refraction effect in Si, and for Schottky contact photodetectors on III-Vs and Si.