Terahertz-pulse emission through laser excitation of surface plasmons in a metal grating.
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 that relies on the excitation of surface plasmons in metal films deposited on a shallow grating. Multiphoton ionization and ponderomotive acceleration of electrons in the enhanced evanescent field of the surface plasmons 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.
Welsh
Gregor H
GH
Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, Scotland, UK.
Hunt
Neil T
NT
Wynne
Klaas
K