Abstract

Superimposed multiple shots of femtosecond (fs) laser pulses can sculpt periodic surface nanostructures on solid surfaces through ablation. Because the period size d is 10–20% of the laser wavelength, this surface phenomenon has attracted considerable interest both for application in laser nanoprocessing technique beyond the diffraction limit of light and for understanding unknown physical mechanism. Recently, one of the dominant physical processes has been proposed that the moderate fs laser pulses can excite surface plasmon polaritons (SPPs) at the interface between the target substrate and the thin layer with high-density electrons generated [1]. Nowadays, based on the physical mechanism, we can form single-spatial-frequency nanostructures, nanograting, on GaN, Ti, and stainless steel [2], as shown in Fig. 1(a).

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