Direct 3D Patterning of TiO₂ Using Femtosecond Laser Pulses

Direct 3D patterning of TiO2 with femtosecond laser pulses using a sol–gel-based negative-tone spin-coatable TiO2 resist is demonstrated (see figure). A layer of the resist was spun on glass and patterned in three dimensions by exposing it to femtosecond laser pulses and then developing in acetone. Heat treatment at 400 °C in air gave 3D patterns that were ca. 50 % of their original size.