Abstract

Optical phenomena experience a giant enhancement in metal nanocomposites and rough thin films consisting of small nm-sized particles and roughness features, respectively. The enhancement is associated with excitation of surface plasmons which are collective modes and strongly depend on the morphology (geometrical structure) of the material. Fractal structures are prevalent in composites and cold-deposited thin films. The emergence of fractal geometry was a significant breakthrough in the description of irregularity. Fractal objects do not possess translational invariance and, therefore, cannot transmit running waves. Accordingly, collective excitations, such as surface plasmons, tend to be localized in fractals [1,2]. Formally, this is a consequence of the fact that plane running waves are not eigenfunctions of the operator of dilation symmetry characterizing fractals.

© 1996 Optical Society of America