Fabrication of computer-generated holograms on silicon by femtosecond laser-assisted with chemical etching

We proposed a simple and flexible method for fabricating computer-generated holograms (CGHs) on crystalline silicon via femtosecond laser-assisted with chemical etching. Femtosecond laser irradiation led to the transformation of crystalline silicon into amorphous silicon, and its chemical activity is significantly reduced, so it can be used as an etching mask in alkaline solution. The amorphous silicon mask led to the formation of nanopillar structure after wet etching. The height of the nanopillars could be flexibly adjusted by controlling the etching time. By means of laser dynamic scanning, we realized the fabrication of holographic array on silicon. The diffraction pattern of the CGHs on silicon becomes clearer with the increase of the height of the nanopillar.