Metasurface-Enabled Astronomical Polarimetry

TL;DR

This paper introduces SIMPol, a novel metasurface-based solar polarimeter that enables high-efficiency, snapshot imaging polarimetry of the sun, demonstrating its practical application in astronomical observations and showcasing the potential of metasurfaces in astronomy.

Contribution

The paper presents the first application of a metasurface polarization grating in a telescope for solar polarimetry, achieving high efficiency and polarization contrast in real astronomical observations.

Findings

Successfully integrated SIMPol into a major observatory telescope.

Detected Zeeman polarization signatures in solar spectral lines.

Achieved nearly 70% efficiency with high polarization contrast.

Abstract

In the last decade or so, metasurface optical components have received considerable scientific and industrial interest for a variety of applications. The miniaturization afforded by metasurfaces could benefit astronomy in particular (which is an often-cited potential application area for metasurfaces). However, few developed examples in which metasurface components offer a unique benefit to astronomical instrumentation - substantiated by the production of scientific data - have been shown. Here, we present the Solar Imaging Metasurface Polarimeter (SIMPol), a first-of-its-kind telescope for snapshot imaging polarimetry of the sun around a Sr I line at 460.7 nm enabled by a metasurface polarization-analyzing grating. This high-performance grating exhibits an overall efficiency of nearly 70% and high polarization contrast (diattenuation) across its four observation channels. We demonstrate SIMPol's integration into a major observatory telescope facility with two different imaging modes. In both cases, Zeeman polarization signatures were clearly observed in two adjacent spectral lines of Fe I and Sr I around 460.7 nm. This work demonstrates an early success of metasurface polarization optics in a real application in astronomical instrumentation (here, polarimetric observations of the solar atmosphere), and heralds the application of metasurfaces and emergent nanophotonic technologies in astronomy more broadly.