Optical recording media using laser-induced size reduction of Au nanoparticles

Silica-gel films containing Au nanoparticles were fabricated by a photoreduction method, which functioned as a medium for high-density optical recording. On irradiation of 532 nm laser light, which corresponds to the surface plasmon resonance absorption of Au particles, the absorption spectrum of the film showed a blueshift. Using this property, a hologram was recorded on the film. Transmitting electron microscopy supported that the change in absorption spectrum was due to size reduction of embedded particles caused by laser irradiation. For recording the hologram, a threshold of laser fluence existed which corresponded to the heat of vaporization of Au particles.