Nanoscale material redistribution induced by spatially modulated femtosecond laser pulses for flexible high-efficiency surface patterning.

In this paper, we investigated the material redistribution phenomenon controlled by spatially modulated femtosecond laser pulses on a silicon surface. The intensity distribution was shaped by using a spatial light modulator. The material was first selectively melted and then redistributed by the laser-induced plasma. Thus, complex surface patterns were formed conformal to the laser intensity distribution. Sub-diffraction-limit size can be achieved due to the nanoscale material redistribution. Only one pulse was needed in the surface patterning process, thus greatly favoring the efficiency improvement. Combined with multibeam interference, a large-scale nanostructure array can be fabricated with high efficiency of 1600 μm/pulse. This method offers a simple, flexible and efficient alternative approach for nanoscale surface patterning applications.