3D Stokes polarimetric imaging at nanoscales

TL;DR

This paper introduces a novel 3D Stokes polarimetric imaging technique at nanoscale resolution, enabling detailed polarization mapping of nonparaxial optical fields in microscopy and nanophotonics.

Contribution

It extends classical Stokes polarimetry into the nonparaxial regime using nanosphere probes and a computational algorithm for efficient polarization state extraction.

Findings

Achieved nanoscale 3D polarization imaging over tens of micrometers.

Demonstrated applicability to single-molecule fluorescence microscopy.

Provided a simple, high-throughput imaging system for complex polarization fields.

Abstract

Optical fields polarized along three dimensions are frequent in optical microscopy and nanophotonics, and yet retrieving their polarization distribution is challenging. We present the experimental implementation of three-dimensional (3D) Stokes polarimetric imaging of nonparaxial optical fields with nanoscale spatial resolution. This approach extends classical Stokes polarimetry (traditionally limited to paraxial fields) into the nonparaxial regime. We use an array of gold nanospheres, each acting as a localized electric dipolar scatterer, to probe 3D polarization states over a field of view of tens of micrometers. The scattered signal is collected by a high numerical aperture objective lens and separated into its circular polarization components, providing a very simple imaging system. We introduce a computational algorithm to efficiently extract the physical parameters from the generated dipole spread functions with a high throughput across the whole field of view. Finally, we show that this method can also be applied to single-molecule localization and orientation fluorescence microscopy.