Physics

Transverse plane

Optical force

Mathematics

Laser

Structural engineering

Optics

Limit (mathematics)

Engineering

Mathematical analysis

Physical chemistry

Diffraction

Chemistry

Optical tweezers

Polarization (electrochemistry)

Photonics

Measure (data warehouse)

Optical path

Computer science

Database

Nature Communications

Accurately measuring mechanical displacements is essential for a vast portion of current technologies. Several optical techniques accomplish this task, allowing for non-contact sensing even below the diffraction limit. Here we introduce an optical encoding technique, dubbed "linear photonic gears", that enables ultra-sensitive measurements of a transverse displacement by mapping it into the polarization rotation of a laser beam. In ordinary ambient conditions, we measure the relative shift between two objects with a resolution of 400 pm. We argue that a resolution of 50 pm should be achievable with existing state-of-the-art technologies. Our single-optical-path scheme is intrinsically stable and it could be implemented as a compact sensor, using cost effective integrated optics. We anticipate it may have a strong impact on both research and industry.

Ultra-sensitive measurement of transverse displacements with linear photonic gears