Abstract

Large third-order optical susceptibilities have been reported for gold clusters in dielectric media at 532 nm, close to the surface plasmon resonance. The nonlinear optical (NLO) mechanism has been attributed by Hache et al.,¹ to optical heating of the electron gas, which results in a refractive index modulation due to Fermi smearing in the vicinity of the L point of the Brillouin zone. Evidence for electron heating in gold films was also observed in transient reflectivity measurements, which reported energy transfer from the hot electron gas to the lattice within several picoseconds.^2,3 Previous measurements of degenerate four-wave mixing (DFWM) in gold clusters, using 5–35-ps pulses, did not resolve this dynamic response.

© 1994 Optical Society of America