Sidewall Roughness Measurement of Photonic Wires and Photonic Crystals

The performance of nanophotonic building blocks such as photonic wires and photonic crystals are rapidly improving, with very low propagation loss and very high cavity Q-factors being reported. In order to facilitate further improvements in performance the ability to quantitatively measure topological imperfections such as sidewall roughness on a sub-nm scale becomes essential. In this paper we use atomic force microscopy (AFM) on tilted samples to obtain the most detailed sidewall roughness measurements yet on nanophotonic structures.