Femtosecond laser-induced spatial-frequency-shifted nanostructures by polarization ellipticity modulation

We demonstrate a prominent spatial frequency shift (SFS) for the femtosecond laser-induced periodic structures by only changing the polarization ellipticity of the working laser. The nanostructures are fabricated on the surfaces of silicon (Si) and zinc selenide (ZnSe) using elliptically polarized femtosecond laser pulses, with the pulse duration of 35 fs, the central wavelength of 800nm, and the repetition rate of 1kHz. The experimental results show that the red- and blue-shift trends of the SFS are individually represented on silicon and zinc selenide with the increased polarization ellipticity, where low- and high-spatial-frequency nano-ripples are fabricated, respectively. These unique phenomena are explained by using the laser-surface plasmon polariton interference mechanism and the effective medium theory. The proposed nanostructures with regulatable period are further used for creating nano-gratings on silicon which perform chirped characteristics. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

By changing the polarization ellipticity of the working laser, a prominent spatial frequency shift (SFS) for femtosecond laser-induced periodic structures is demonstrated. This results in the fabrication of unique nanostructures on silicon and zinc selenide with different characteristics as low- and high-spatial-frequency nano-ripples, respectively. These phenomena are explained using laser-surface plasmon polariton interference mechanism and effective medium theory.