Interplay between diffraction and the Pancharatnam-Berry phase in inhomogeneously twisted anisotropic media

TL;DR

This paper explores how the interplay of diffraction and the Pancharatnam-Berry phase in inhomogeneously twisted anisotropic media influences electromagnetic wave propagation, revealing effective photonic potentials and guided modes.

Contribution

It demonstrates the origin of photonic potentials from the Pancharatnam-Berry phase and Kapitza effect, supported by theoretical and numerical analysis of inhomogeneously twisted anisotropic media.

Findings

Photonic potential arises from the Pancharatnam-Berry phase.

The effective potential supports transverse confinement of light.

Configuration supports non-leaky guided modes.

Abstract

We discuss the propagation of an electromagnetic field in an inhomogeneously anisotropic material where the optic axis is rotated in the transverse plane but is invariant along the propagation direction. In such a configuration, the evolution of an electromagnetic wavepacket is governed by the Pancharatnam-Berry phase (PBP), responsible for the appearance of an effective photonic potential. In a recent paper [A. Alberucci et al., "Electromagnetic confinement via spin-orbit interaction in anisotropic dielectrics", ACS Photonics \textbf{3}, 2249 (2016)] we demonstrated that the effective potential supports transverse confinement. Here we find the profile of the quasi-modes and show that the photonic potential arises from the Kapitza effect of light. The theoretical results are confirmed by numerical simulations, accounting for the medium birefringence. Finally, we analyze in detail a configuration able to support non-leaky guided modes.