Electromagnetic waves, solutions to Maxwell’s equations, are
"transverse" in vacuum. Namely, the waves’ oscillatory electric and
magnetic fields are confined within a plane transverse to the waves’
propagation direction. Thus, the polarisation of these fields can be
described by an arbitrary vectorial superposition of two vectors lying
in the transverse plane. Though spatially uniform polarised beams are
widely used in optics, spatially structured polarised beams have
received much attention in the last decades. Such beams may possess
well-defined polarisation topological structures in the transverse
plane, which is isolated and preserved upon free-space propagation.
Under tight-focusing conditions, the polarisation of these beams can
exhibit three-dimensional structures, and may result in beams possessing
longitudinal electric or magnetic field. Such structures can exhibit
features such as transverse spin angular momentum; and non-trivial
topologies such as Möbius or Ribbon strips.
In my talk, I will present the recent progress, challenges, and
developments in structuring the polarisation of optical beams. The
stability and the dynamics of two- and three-dimensional polarisation
topologies, e.g. Möbius and Ribbon strips, as well as knots, will also
be the subject of my presentation.