Optical Dielectric Apertureless Probe for Surface Laser Modification with λ/15 Lateral Resolution

Abstract

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. 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 by single nanosecond laser pulses focused through the fiber dielectric apertureless probe. The resulting structures were imaged via scanning electron and atomic force microscopy. It was shown that both the shape and sizes of the obtained microstructures are determined by the pulse energy and film thickness.