Terahertz-pulse emission through laser excitation of surface plasmons in a metal grating

Welsh, G.H. and Hunt, N.T. and Wynne, K. (2007) Terahertz-pulse emission through laser excitation of surface plasmons in a metal grating. Physical Review Letters, 98 (2). 026803. ISSN 0031-9007

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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 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.