Self-Trapping of Light Using the Pancharatnam-Berry Phase

Chandroth P Jisha,Alessandro Alberucci,Jeroen Beeckman,Stefan Nolte

doi:10.1103/physrevx.9.021051

Abstract

Since its introduction by Sir Michael Berry in 1984, geometric phase became of fundamental importance in physics, with applications ranging from solid state physics to optics. In optics, Pancharatnam-Berry phase allows the tailoring of optical beams by a local control of their polarization. Here we discuss light propagation in the presence of an intensity-dependent local modulation of the Pancharatnam-Berry phase. The corresponding self-modulation of the wavefront counteracts the natural spreading due to diffraction, i.e., self-focusing takes place. No refractive index variation is associated with the self-focusing: the confinement is uniquely due to a nonlinear spin-orbit interaction. The phenomenon is investigated, both theoretically and experimentally, considering the reorientational nonlinearity in liquid crystals, where light is able to rotate the local optical axis through an intensity-dependent optical torque. Our discoveries pave the way to the investigation of a new family of nonlinear waves featuring a strong interaction between the spin and the orbital degrees of freedom.

Highlights

The geometric phase is of primary importance in modern physics [1,2,3,4,5,6,7,8]
The PancharatnamBerry phase (PBP), experimentally demonstrated in 1988 in a laser interferometer [17], is not the only phenomenon in classical optics related to the geometric phase: The rotation of the beam polarization caused by a three
The different lines correspond to a maximum rotation angle θmax of 5°, 15°, and 45°, respectively. (e) Distribution of the rotation θ on the plane xz and (f) the corresponding cross section versus x, taken in the section where the rotation angle is maximum; the input parameters are w 1⁄4 2 μm, and the power density is 2 × 103 W m−1

Summary

Introduction

The geometric phase is of primary importance in modern physics [1,2,3,4,5,6,7,8] It arises when a classical or quantum system encompasses a variation of its parameters [9,10], such as a magnetic dipole moving in a rotating magnetic field [11,12]. Pancharatnam found that photons acquire a phase during polarization evolution; this phase depends on the area subtended by the path on the Poincaresphere This phase, dubbed the PancharatnamBerry phase (PBP), is responsible for a new set of optical phenomena, collectively called spin-orbit photonics [15,16]. The PBP, experimentally demonstrated in 1988 in a laser interferometer [17], is not the only phenomenon in classical optics related to the geometric phase: The rotation of the beam polarization caused by a three-

Methods

Results

Conclusion