Terahertz-pulse emission through excitation of surface plasmons in metallic nanostructures

Abstract

The second-order processes of optical rectification and photoconduction are well known and widely used to produce ultrafast electromagnetic pulses in the terahertz frequency domain. We present a new form of rectification relying on the excitation of surface plasmons (SPs) in metallic nanostructures. Multiphoton ionization and ponderomotive acceleration of electrons in the enhanced evanescent field of the SPs, results in a femtosecond current surge and emission of terahertz electromagnetic radiation. Using gold, this rectification process is third or higher order in the incident field.