Generation of ultrafast terahertz radiation pulses on metallic nanostructured surfaces

Welsh, G.H. and Wynne, K. (2009) Generation of ultrafast terahertz radiation pulses on metallic nanostructured surfaces. Optics Express, 17 (4). pp. 2470-2480. ISSN 1094-4087 (http://dx.doi.org/10.1364/OE.17.002470)

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Abstract

A resonant "incoherent" rectification process is presented relying on the excitation of surface plasmons on a nanostructured metal surface. Excitation of gold and silver films with 800-nm femtosecond laser pulses results in the emission of terahertz radiation with an angle-dependent efficiency and an approximately third-order power dependence. It is shown that the source of this terahertz pulse generation is the surface-plasmon-assisted multiphoton ionization and ponderomotive acceleration in the evanescent field of the surface plasmon. Simple models are used to understand the forces and dynamics near the surface.