Waveguiding driven by the Pancharatnam-Berry phase

TL;DR

This paper explores waveguides created by the Pancharatnam-Berry phase through theoretical and numerical analysis, revealing polarization evolution and analogies with magnetic fields, advancing understanding of geometric phase effects in optical waveguides.

Contribution

It introduces a novel waveguide design based on the Pancharatnam-Berry phase with detailed analysis of polarization dynamics and geometric phase accumulation.

Findings

Polarization structure of quasi-modes evolves continuously.

Net geometric phase accumulation affects waveguide properties.

Analogies with charged particles in magnetic fields are established.

Abstract

We theoretically and numerically investigate the properties of waveguides based on the Pancharatnam-Berry phase, obtained by a longitudinally periodic rotation of the optic axis in a transversely-twisted birefringent medium. In this paper we study the case where the period of the longitudinal modulation is chosen so that a net accumulation of geometric phase in propagation occurs. First, the interplay between different contributions to the optical potential is addressed. Second, a continuous evolution of the polarization structure of the quasi-modes is observed in the numerical simulations. We explain it by a combination of plane-wave-based models and gauge transformations. We discover that, beyond the longitudinal oscillations, the polarization of the quasi-mode also varies through its cross-section. The analogies with respect to charged particles moving in a magnetic field are outlined.