Plasmonic grating for circularly-polarized out-coupling of waveguide-enhanced spontaneous emission

TL;DR

This paper demonstrates a plasmonic nanoparticle lattice on a dielectric waveguide that efficiently couples circularly polarized light into guided modes, achieving high polarization purity despite metal losses, and offers a new approach for integrated photonic devices.

Contribution

It introduces a novel plasmonic grating that enables efficient circular polarization control and out-coupling in waveguide systems, overcoming typical metal loss limitations.

Findings

Achieved 80% circular polarization degree in out-coupled emission.

Demonstrated efficient coupling of circularly polarized light into guided modes.

Validated the potential for integrated photonic device applications.

Abstract

Plasmonic metasurfaces form a convenient platform for light manipulation at the nanoscale due to their specific localized surface plasmons. Nevertheless, despite the high degree of light localization in metals, their intrinsic Joule losses are often considered prevention from applications in high-quality dielectric structures. Here, we experimentally demonstrate that in some cases, the capabilities of plasmonic particles for light manipulation prevail over the negative impact of absorption. We show the lattice of plasmonic nanoparticles onto a dielectric waveguide that efficiently couples the light of both circular polarizations to guided modes propagating in opposite directions. We demonstrate 80% degree of circular polarization for the out-coupled emission of GaAs-waveguide-embedded quantum dots. The results allow us to consider the lattice as a circular-polarization-controlled grating coupler operating at normal incidence and make this structure prospective for further implementation as an efficient coupling interface for various integrated devices.