Nanofabrication induced by near-field exposure from a nanosecond laser pulse

We demonstrate a photoinduced nanofabrication method, applicable to dimensions beyond the diffraction limit, by employing a nanosecond laser pulse with a high peak power. The second-harmonic wave of a Nd: yttrium-aluminum-garnet (YAG) laser with a 5 ns pulse width was irradiated onto the sample, which consisted of a hexagonal arrayed monolayer of nanoparticles on an azopolymer film. Topographical changes in the surface after irradiation were observed by atomic force microscopy. A transcription of the arrayed structure in the form of a dent structure was attained. In the case of 100 nm nanoparticles, the resolution of the transcription was beyond the diffraction limit. The dent depth and diameter were changed depending on the diameter of the nanoparticles and the irradiation power used. A depth analysis indicates a threshold for the ablation process. (C) 2001 American Institute of Physics.