A high-precision silicon-on-insulator position sensor

Integrated photonic devices provide significant advantages over their conventional counterparts, such as a drastically reduced footprint as well as compatibility with other photonic or electronic circuitry. In this work, we present a high-precision optical position sensor fabricated on a silicon-on-insulator platform. The sensor relies on the principle of position-dependent directional waveguide coupling upon excitation of a monolithically integrated scatterer with a tightly focused polarization-tailored beam. We demonstrate a spatial resolution of 7.2 nm, corresponding to approximately ?/200.