Electromagnetic confinement via spin-orbit interaction in anisotropic dielectrics

TL;DR

This paper demonstrates how geometric phases from spin-orbit interactions in anisotropic dielectrics can induce electromagnetic confinement and waveguiding without traditional refractive index gradients, supported by theoretical and numerical analysis.

Contribution

It introduces a novel mechanism for electromagnetic confinement using geometric phases in uniaxial dielectrics with varying optic axis orientations, bypassing refractive index modifications.

Findings

Geometric phase induces an effective potential for waveguiding.

Theoretical results validated by numerical simulations of Maxwell's equations.

Potential for new guided wave structures without refractive index tailoring.

Abstract

We investigate electromagnetic propagation in uniaxial dielectrics with a transversely varying orientation of the optic axis, the latter staying orthogonal everywhere to the propagation direction. In such a geometry, the field experiences no refractive index gradients, yet it acquires a transversely-modulated Pancharatnam-Berry phase, that is, a geometric phase originating from a spin-orbit interaction. We show that the periodic evolution of the geometric phase versus propagation gives rise to a longitudinally-invariant effective potential. In certain configurations, this geometric phase can provide transverse confinement and waveguiding. The theoretical findings are tested and validated against numerical simulations of the complete Maxwell's equations. Our results introduce and illustrate the role of geometric phases on electromagnetic propagation over distances well exceeding the diffraction length, paving the way to a whole new family of guided waves and waveguides which do not rely on refractive index tailoring.