Emission of pulses of electromagnetic radiation in the terahertz range is observed when ultrathin gold films on glass are illuminated with femtosecond near-IR laser pulses. A distinct maximum is observed in the emitted terahertz amplitude from films of average thickness just above the percolation threshold. Our measurements suggest that the emission is through a second-order nonlinear optical rectification process, enhanced by the excitation of localized surface plasmon hot spots on the percolated metal film.
© 2011 Optical Society of America
Optics at Surfaces
Original Manuscript: May 10, 2011
Revised Manuscript: June 2, 2011
Manuscript Accepted: June 10, 2011
Published: July 1, 2011
Gopakumar Ramakrishnan and Paul C. M. Planken, "Percolation-enhanced generation of terahertz pulses by optical rectification on ultrathin gold films," Opt. Lett. 36, 2572-2574 (2011)