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

Welsh, G.H. and Hunt, N.T. and Wynne, Klaas; (2007) Terahertz-pulse emission by laser excitation of surface plasmons in a metal grating. In: 2007 Joint 32nd International Conference on Infrared and Millemeter Waves and 15th International Conference on Terahertz Electronics. IEEE, New York, pp. 884-885. ISBN 978-1-4244-1438-3

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Abstract

Metallic nanostructures have been prepared by depositing thin layers of gold onto a fused-silica transmission grating. Excitation with 800-nm femtosecond laser pulses in air results in the emission of terahertz radiation with an angle-dependent efficiency and a third-order dependence on input power. Nanostructures consisting of metal nano-pyramids on glass as well as silver nano-pyramid arrays covered in gold also exhibit terahertz emission. We will show that the source of the terahertz radiation in all of these cases is surface-plasmon-assisted multiphoton ionisation and ponderomotive acceleration in the evanescent laser field.