Substrate nanomodification based on heating and near field properties of gold nanoparticles

Theoretical and experimental results on nanosized modifications of substrates placed in the near field zone of metal nanoparticles are demonstrated. Gold nanoparticles with diameter of 200 nm are deposited on different substrates (dielectric, semiconductor, and metal) and irradiated by ultrashort laser pulses at wavelength of 800 nm. Formation of surface modification under the nanoparticles is observed at laser fluences below the modification threshold of the bulk substrate. The mechanisms of the surface modifications are explained by the heating of the nanoparticles and by the local field enhancement in their vicinity. The heating of the nanoparticle is described by two-temperature diffusion model as the input optical properties of the nanoparticles are evaluated on the basis of the Mie theory. The near field distribution is obtained by finite difference time domain (FDTD) simulation. The influence of the incident irradiation properties and the dielectric properties of the substrates on the modification characteristics is discussed.