Laser-assisted nanostructuring of metal films by means of a fibre dielectric microprobe

A simple apertureless dielectric microprobe in the form of a section of the tapered optical fibre was proposed for surface laser nanomodification. This probe enables surface λ/2-localisation of laser beam, as demonstrated both numerically and experimentally. The controllable formation of single through nanoholes with the minimum size down to 35 nm (∼λ/15) in the 50-nm Au/Pd film was shown using this probe and a 532-nm pump nanosecond laser. We also report for the first time on the formation of micro- and nanobumps, jet-like microstructures and microholes on optically thick gold films using single nanosecond laser pulses focused through the fibre dielectric apertureless probe. Both the shape and the sizes of the obtained microstructures were demonstrated to be determined by the pulse energy and film thickness.