Black Titanium Dioxide in Situ Generated on Femtosecond Laser Induced Periodic Surface Structures

Titanium dioxide (TiO
₂
) is in the focus of research for applications in gas sensors, solar cells photo catalysis, electronics and batteries. We demonstrate a simple confined laser plasma ablation method providing simultaneously laser induced periodic surface structures (LIPSS) in the micro-and nanometer range, covered by nano-textured black TiO
₂
. In addition we utilize the LIPSS formation and etalon effects of the confined ablation method to fabricate hollow silicon (Si) needles 10 μm in diameter and 60 μm in length as well as Si-metal-box structures with submicron wall thickness in combination with deep reactive ion etching (DRIE). The gentle field modulation by the ablation etalon reveals some aspects of the LIPSS formation dynamics. Our results on Si and metals show, high spatial frequency LIPSS (HSFL) are first generated parallel to the laser polarization followed by transformation into pinholes and LIPSS perpendicular to the laser polarization.