Spontaneous micro-modification of single-layer graphene induced by femtosecond laser irradiation

Permanent micro-modifications in single-layer graphene with a spontaneous periodic structural change have been induced by femtosecond (fs) laser irradiation. These modifications present a regular variation along the radial direction from a central ablated region. Based on the obtained micro-Raman spectrum and the reflective micro-spectrum of laser-irradiated graphene, structural modification with periodic variations containing several spectral regimes has been observed, which was in good agreement with periodic topography of the structure observed using an atomic force microscope. It has also been found that several regions of the laser induced structures were with different optical properties, which were identified to be correlated with different modification mechanisms. In addition, after fs laser processing, graphene still maintains crystallinity. This work may be helpful for the development of graphene-based microstructures or devices by fs laser pulses.