Fabrication of Novel Structures on Silicon with Femtosecond Laser Pulses

In this study, the fabrication of novel micro/nano structures were induced on silicon surfaces using radially and azimuthally polarized femtosecond laser, with a similar to 120 fs pulse duration, an 800 nm wavelength, and a 1 kHz repetition rate. Results showed that, as the laser fluence approached the ablation threshold of the silicon, nanostructures with a period of approximately 600 similar to 700 nm were formed at the low laser fluence region (0.7 similar to 0.8 J/cm(2)), and their orientations were perpendicular to the laser polarization. However, as the laser fluence increased (0.9 similar to 1.1 J/cm(2)), microstructures with a period of approximately 2 similar to 3 mu m were formed, and their orientation were parallel to the laser polarization.