Nanostructuring of thin gold films by femtosecond lasers

Novel experimental data on microstructuring of thin (60 nm) gold films by femtosecond laser pulses are presented and discussed. Material modifications are induced by different laser field distributions on the sample surface. Images of specially fabricated masks are transferred onto the gold surface with a 50x and 100x demagnifications. It is shown that, in the irradiated region of the gold film, the heated material tends to concentrate in the center. For example, a square-like field distribution on the target surface produces a cross with a jet in the middle. It is shown that this technique allows producing of a variety of microstructures with controllable nanorelief. Possible mechanisms leading to the observed material modifications as well as the resolution limits of this technique are discussed.