Fabrication of concave silicon micro-mirrors

We have fabricated spherical and cylindrical concave micro-mirrors in silicon with dimensions from 20 mu m to 100 mu m. The fabrication process involves standard photolithography followed by large area ion beam irradiation and electrochemical anodisation in a HF electrolyte. After thermal oxidation the silicon surface roughness is less than 2 nm. We also present a multilayer porous silicon distributed Bragg reflector fabricated on concave silicon surfaces which selectively reflect and focus a band of wavelengths from a parallel beam of incident white light. Development of such low roughness concave microstructures opens up new applications in areas such as silicon photonics and quantum information science. (C) 2010 Optical Society of America