Optical apertureless fiber microprobe for surface laser modification of metal films with sub-100Â nm resolution

A simple apertureless dielectric microprobe in the form of a section of the tapered optical fiber was proposed for surface laser nanomodification. This probe enables surface λ/2-localization of laser beam, as shown both numerically and experimentally. Single nanoholes with the minimum size down to 90 nm (∼λ/6) were fabricated in the 25-nm Au/Pd film, using this probe and a 532-nm pump nanosecond laser.