High aspect ratio nano-structures (HARNS) for photonic MEMS based on vertical DBR architecture

High aspect ratio nano-structures (HARNS), having an aspect ratio of up to 107, were fabricated by DRIE (deep reactive ion etching). Sidewall surface roughness was reduced to a level less than 20 nm peak-to-valley. These technological advances are applied to photonic MEMS based on in-plane, free-space propagation of light. As an illustration, a Fabry-Perot cavity is presented. It uses vertical distributed Bragg reflectors (DBRs), which consist of thin silicon walls separated by small air gaps, the widths being an even multiple of quarter wavelengths of light in silicon and in air, respectively.