Compact All-Metasurface Interferometer for High-Precision Displacement Sensing

Abstract

Compact and high-precision displacement sensing is a prerequisite for next-generation photolithography and nanomanufacturing. While metasurface-based sensors offer miniaturization, existing solutions inevitably resort to external optical systems of prisms or bulky lens for beam manipulation, hindering full integration of compact devices. Here, we propose a scheme of all-metasurface interferometry with ultrahigh sensitivity displacement sensing within a microscopic footprint. A Pancharatnam–Berry (PB) phase gradient metasurface initially encodes transverse displacement into a spin-dependent phase shift via large-angle diffraction (12°), while a polarization-multiplexed bifocal metalens subsequently recombines the beams to perform the differential phase-to-intensity conversion. Numerical results indicate a theoretical displacement resolution approaching 50 pm under ideal conditions with intrinsic common-mode noise suppression, achieved without any bulk optical components. This work presents a robust strategy for on-chip metrology, bridging the gap between picometer-level precision and integrated photonics.