Active plasmonic nanoantenna: an emerging toolbox from photonics to neuroscience

Concepts adapted from radio frequency devices have brought forth subwavelength scale optical nanoantenna, enabling light localization below the diffraction limit. Beyond enhanced light–matter interactions, plasmonic nanostructures conjugated with active materials offer strong and tunable coupling between localized electric/electrochemical/mechanical phenomena and far-field radiation. During the last two decades, great strides have been made in development of active plasmonic nanoantenna (PNA) systems with unconventional and versatile optical functionalities that can be engineered with remarkable flexibility. In this review, we discuss fundamental characteristics of active PNAs and summarize recent progress in this burgeoning and challenging subfield of nano-optics. We introduce the underlying physical mechanisms underpinning dynamic reconfigurability and outline several promising approaches in realization of active PNAs with novel characteristics. We envision that this review will provide unambiguous insights and guidelines in building high-performance active PNAs for a plethora of emerging applications, including ultrabroadband sensors and detectors, dynamic switches, and large-scale electrophysiological recordings for neuroscience applications.