Terahertz polarimetry with a monolithic metasurface

Abstract

The state of polarization (SoP) is a fundamental property of electromagnetic radiation that can carry a rich set of important information in light transmitted through a test sample. Despite a wide range of applications in material identification, (thin-film) characterization, and defect analysis, the SoP remains difficult to exploit—especially at terahertz frequencies since its measurement requires complex apparatuses with multiple moving parts. We have addressed these challenges by designing a metasurface polarimeter (MSP) that incorporates the entire functionality of a division of aperture polarimeter (DoAP) with high efficiency into a single silicon layer without the need for moving parts. Collective simulations are in perfect agreement with experimental data, both confirming the intended operation. Furthermore, we present an automated analysis algorithm that allows for the complete determination of the SoP from a single image with an experimental accuracy of 92.1% ± 4.2%, following an initial calibration. We anticipate that the presented MSP will find applications in polarimetric sensing and imaging for non-destructive evaluation at terahertz frequencies.