Magneto-optical polarisation texturing

TL;DR

This paper explores how magneto-optical effects in magnetic materials can be used to shape the polarization of Laguerre-Gaussian beams, including the impact of longitudinal field components on polarization textures.

Contribution

It demonstrates the use of magneto-optical effects for vectorial polarization shaping of LG modes and analyzes the influence of beam waist size on polarization textures.

Findings

Magneto-optical effects enable polarization shaping of LG modes.

Longitudinal field components affect polarization textures.

Material and geometry choices control the polarization map.

Abstract

Left and right circularly polarized transverse electromagnetic waves propagate at slightly different speeds in a magnetic material leading to a polarization rotation by an amount proportional to the projection of the magnetic field along the direction of the wave propagation. We show how this magneto-optical effect can serve as a vectorial polarization shaper if the input mode is either a radially-polarised or an azimuthally-polarised Laguerre-Gaussian (LG) mode. The specific polarization map of the output field can be achieved by choosing appropriately the magnetic material and/or its geometry. We show further that when the LG beam waist is comparable to the wavelength the fields are no longer purely transverse but acquire an additional longitudinal (axial) component. We demonstrate how this modifies the polarisation texturing.