Abstract

The local field enhancement connected with surface plasmon (SP) excitations in metal nanoparticles represents the basis for many linear and nonlinear optical effects and various important applications.^1,2 Accordingly, it is of great interest to realize large enhancement factors, i.e., low homogeneous linewidths of SP resonances in metal nanoparticles. SP resonances seen in linear optical far-field spectra of ensembles of metal nanoparticles are inhomogeneously broadened. Due to its shortness, the dephasing time T₂ of a SP excitation (the inverse of the homogeneous linewidth) has not been measured yet. Thus the homogeneous linewidths of SPs and their dependencies on the nanoparticle parameters and the embedding matrix are not known and systematic optimization of the field enhancement factor is difficult to achieve.

© 1998 Optical Society of America