Light scattering from dipole and quadrupole nanoshell antennas

Metal nanoshells are nanoscale optical components that allow for the contro llable redirection of electromagnetic radiation via careful engineering of their multilayer structures. By varying the core size and shell thickness o f these nanoparticles, nanoscale "antennas" are constructed that can be sel ectively driven into a dipolar or quadrupolar oscillation pattern. With sca ttering cross sections many times larger than their physical cross section, these antennas efficiently couple to the incident electromagnetic wave. Th ese structures can focus, redirect, or split the incident light with subwav elength precision, and may find useful applications in the remote coupling of electromagnetic signals into nanoscale machines or devices. (C) 1999 Ame rican Institute of Physics. [S0003-6951(99)02432-8].