Towards integrated position sensors with nanometer precision

Abstract

The ability to precisely measure the displacement between two elements, e.g. a mask and a substrate or a beam and optical elements, is fundamental to many precision experiments and processes. Yet typical optical displacement sensors struggle to go significantly below the diffraction limit. Here we combine advances in our understanding of directional scattering from nanoparticles with silicon photonic waveguides to demonstrate a displacement sensor with deep subwavelength accuracy. Depending on the level of integration and waveguide geometry used we achieve a spatial resolution between 5 − 7 nm, equivalent to approximately λ/200 − λ/300.