Fabrication of microlenses with continuously variable numerical aperture through a temporally shaped femtosecond laser

We developed a novel method for fabricating microlenses and microlens arrays by controlling numerical aperture (NA) through temporally shaped femtosecond laser on fused silica. The modification area was controlled through the pulse delay of temporally shaped femtosecond laser. The final radius and sag height were obtained through subsequent hydrofluoric acid etching. Electron density was controlled by the temporally shaped femtosecond laser, and the maximum NA value (0.65) of a microlens was obtained in the relevant studies with femtosecond laser fabrication. Furthermore, the NA can be continuously adjusted from 0.1 to 0.65 by this method. Compared with the traditional methods, this method exhibited high flexibility and yielded microlenses with various NAs and microlens arrays to meet the different demands for microlens applications.