Waveguide metacouplers for in-plane polarimetry

TL;DR

This paper introduces a compact, in-plane polarimeter using plasmonic metasurfaces that directly measures the state of polarization of light by coupling it into waveguide modes, enabling immediate SOP retrieval.

Contribution

It presents a novel waveguide metacoupler design based on plasmonic phase-gradient birefringent metasurfaces for in-plane polarimetry, which is compact and suitable for integrated optical circuits.

Findings

Confirmed functionality through full-wave simulations at 1.55 μm wavelength.

Demonstrated direct measurement of Stokes parameters from coupling efficiencies.

Showed potential for integration into remote sensing systems.

Abstract

The state of polarization (SOP) is an inherent property of the vectorial nature of light and a crucial parameter in a wide range of remote sensing applications. Nevertheless, the SOP is rather cumbersome to probe experimentally, as conventional detectors only respond to the intensity of the light, hence loosing the phase information between orthogonal vector components. In this work, we propose a new type of polarimeter that is compact and well-suited for in-plane optical circuitry, while allowing for immediate determination of the SOP through simultaneous retrieval of the associated Stokes parameters. The polarimeter is based on plasmonic phase-gradient birefringent metasurfaces that facilitate normal incident light to launch in-plane photonic waveguide modes propagating in six predefined directions with the coupling efficiencies providing a direct measure of the incident SOP. The functionality and accuracy of the polarimeter, which essentially is an all-polarization sensitive waveguide metacoupler, is confirmed through full-wave simulations at the operation wavelength of 1.55$\mu$m.