title: Electromagnetic Confinement via Spin-Orbit Interaction in Anisotropic Dielectrics.
abstract: We investigate electromagnetic propagation in uniaxial dielectrics with a transversely varying orientation of the optic axis, the latter staying orthogonal everywhere in 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 that do not rely on refractive index tailoring.
authors.affiliation: Optics Laboratory, Tampere University of Technology, FI-33101 Tampere, Finland; NooEL - Nonlinear Optics and OptoElectronics Lab, University "Roma Tre", IT-00146 Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Alberucci
authors.affiliation: Centro de Física do Porto, Faculdade de Ciências, Universidade do Porto , PT-4169-007 Porto, Portugal.
authors.forename: Chandroth P
authors.initials: CP
authors.lastname: Jisha
authors.affiliation: Dipartimento di Fisica, Università di Napoli Federico II, IT-80100 Naples, Italy; CNR-ISASI, Institute of Applied Science and Intelligent Systems, IT-80078 Pozzuoli (NA), Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Marrucci
authors.affiliation: Optics Laboratory, Tampere University of Technology, FI-33101 Tampere, Finland; NooEL - Nonlinear Optics and OptoElectronics Lab, University "Roma Tre", IT-00146 Rome, Italy; CNR-ISC, Institute for Complex Systems, IT-00185 Rome, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Assanto
keywords: Berry phase; Kapitza effect; anisotropic media; spin−orbit photonics; structured beams; waveguides