26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Multi-wavelength polarisation imaging with inverse designed metasurfaces

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Speaker

Sarah E. Dean (ARC Centre of Excellence for Transformative Meta-Optical Systems, Department of Electronic Materials Engineering, Research School of Physics, The Australian National University)

Description

Polarisation imaging is used in remote sensing to capture enhanced information in a scene. Multispectral polarisation imaging, in particular, has agricultural applications such as crop classification and vegetation health monitoring$~$[1]. Drones, small satellites, and other lightweight unmanned aerial vehicles are accessible platforms for remote sensing, but have size and weight limitations that prohibit using conventional full-Stokes polarisation imaging methods. We propose that metasurfaces can be used to perform complex imaging in ultra-compact systems, and present the design, analysis, and experimental testing of a metasurface for multispectral polarisation imaging.

Metasurfaces are photonic devices consisting of an array of nanoresonators with tailored optical transmission resonances. There are many examples of single-shot polarisation imaging with metasurfaces; however, these works are limited to monochromatic light, or use multiple metasurfaces to capture all wavelengths$~$[2]. We extend these works to multispectral polarisation imaging with a single metasurface$~$[3], avoiding imaging offsets and beam-splitting, and ensuring it satisfies the performance requirements of drone-based applications.

We present a diffractive metasurface with a topology-optimised design for multispectral polarimetry at two simultaneous wavelengths, motivated by potential agricultural remote surveying applications. We also analyse critical performance metrics of our design, showing that the metasurface can operate for the required field-of-view and the polarisation reconstruction performance is maintained for spectral bandwidths exceeding 10$~$nm. Finally, we fabricate the metasurface by nanopatterning TiO$_2$ thin film and experimentally demonstrate the polarimetry at 532$~$nm and 637$~$nm optical wavelengths with the single metasurface.

These results establish metasurfaces as an effective platform for complex polarisation- and spectral-resolved imaging in a compact, lightweight footprint.
$\small{\mathrm{[1]~M.~W.~Kudenov~\mathit{et~al},~Appl.~Opt.~ \mathbf{62},~2078~(2023)}}$
$\small{\mathrm{[2]~L.~W.~Li~\mathit{et~al},~Appl.~Opt.~\mathbf{62},~1704~(2023)}}$
$\small{\mathrm{[3]~S.~E.~Dean~\mathit{et~al},~arXiv~2604.27756~(2026)}}$