An experimental investigation into the conversion of optical spin to orbital angular momentum using internal conical diffraction

Abstract

Internal conical refraction (ICR) transforms a ray incident upon the optic axis of a biaxial crystal into a cone of light within the medium and a hollow cylinder of light upon exiting. If the incident ray is circularly polarised each of the electric field components is separated out forming a π rotation of linear polarisation around the ring. The phenomenon of ICR has recently been expanded to incorporate paraxial diffraction of the conical beam (ICD). The paraxial transformation of a Gaussian beam results in the radial electric field of the conical beam described as a superposition of Bessel functions of zero- and first-order.