Ultrafast laser-induced formation of surface micro-structuring on quantum dot coated glass

The fabrication induced by ultrafast laser illumination on solid surface has been widely illustrated in the field of laser physics. A new nanoscale-structure fabrication method based on the local surface plasmon resonance of the quantum dots (QDs) which are adhered on the substrate is demonstrated. By illuminating a K9 substrate which has been coated by Cu2S QDs with femtosecond laser, a series of grating-like and sub-wavelength period strips are achieved. The interval between each strip is nearly 34 nm when the central wavelength, pulse duration and illumination power of the laser are 1300 nm, 50 fs and 230 mW respectively. Moreover, the mechanism of inducing period strips has been demonstrated by the simulated near field distribution of the adhered QDs on substrate. The result shows that the period strips result from the interference between femtosecond laser and localized plasmon induced by QDs. This preparation method can not only reduce the laser threshold of nanoscale-structure fabrication of transparent medium, but also improve the processing technology of the micro-nano structure on the surface of the transparent substrate.