Femtosecond-Laser-Induced All-Silicon Dielectric Metasurfaces Assisted by Wet Chemical Etching

Abstract

All-dielectric metasurfaces offer low material loss and strong field localization and are, therefore, well suited for ultrathin and compact optical devices for electomagnetic wave manipulation at the nanoscale. All-silicon dielectric metasurfaces, in particular, may additionally offer the desired compatibility with complementary metal-oxide semiconductor technology and, hence, are ideal candidates for large-scale monolithic integration on a photonic chip. However, in conventional silicon microfabrication approaches, the combination of mask photolithography with reactive ion etching usually involves expensive masks and multiple preprocessing stages leading to increased cost and fabrication times. In this work, a single-step lithographical approach is proposed for the realization of all-silicon dielectric resonant metasurfaces that involves femtosecond laser processing of silicon below ablation threshold in combination with subsequent wet chemical etching. The method exploits the different etching rate between laser-modified and untreated regions, enabling large-area fabrication of patterned silicon surfaces in a facile and cost-efficient manufacturing approach. It is presented how two-dimensional silicon micro/nanostructures with controllable features, such as nanocones, can be effectively generated and, as a proof of concept, an all-silicon dielectric metasurface device supporting antiferromagnetic order is experimentally demonstrated.