Terahertz-Pulse Emission Through Laser Excitation of Surface Plasmons in a Metal Grating

Phys. Rev. Lett. 98, 026803 (2007)

ulse Emission Through Laser Excitation of Surface Plasmons in a Metal Grating

Gregor H. Welsh, Neil T. Hunt, and Klaas Wynne
Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, Scotland, UK

(Received 28 July 2006; revised 26 September 2006; published 10 January 2007)

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.
URL: http://link.aps.org/abstract/PRL/v98/e026803