Light-induced switching between structural forms with different optical properties in a single gallium nanoparticulate.

In a single gallium nanoparticulate, self-assembled (from an atomic beam) in a nanoaperture at the tip of a tapered optical fiber, we have observed reversible light-induced reflectivity changes associated with a sequence of transformations between a number of structural forms with different optical properties, stimulated by optical excitation at nanowatt power levels. The ability to change the optical properties of a nanoparticulate using structural transformations provides a new mechanism for photonic functionality on the nanoscale.