Geometry Driven Spin Polarization Effects in Waveguiding Plasmonic Crystal

TL;DR

This study explores how the polarization-dependent optical behavior of waveguiding plasmonic crystals can be modulated by changing illumination geometry, revealing circular polarization anisotropy effects even in symmetric, achiral systems.

Contribution

It demonstrates the emergence of circular polarization anisotropy in symmetric plasmonic crystals due to geometrical effects, analyzed through simulations and polarization formalism.

Findings

Circular anisotropy observed at non-zero azimuthal angles.

Polarization effects explained by birefringence and diattenuation.

Implications for spin-orbit interaction in plasmonic systems.

Abstract

We investigated the modulation in the polarization-dependent optical behaviour of the waveguiding plasmonic crystal by varying the illumination and detection geometry. We employed the finite element method-based COMSOL simulation and Jones-Mueller formalisms to probe the variations in optical parameters by systematically varying the angle of incidence and azimuthal angle of the incident plane wave source, thereby quantifying the variations in the polarization anisotropy parameters. The enhancement of optical properties at various resonances and the tunability of the hybridized modes are discussed. Importantly, our study reveals that despite the system being perfectly inversion-symmetric and achiral, it exhibits circular polarization anisotropy effects for non-zero finite azimuthal angles, manifested in the off-block-diagonal elements of the constructed Mueller matrices. The origin of this intriguing circular anisotropy effect is unravelled using the sequential linear birefringence and linear diattenuation effects arising from geometrical polarization transformation. Its implications in the spin-orbit interaction of light in the plasmonic crystal system are discussed.