Crafting the core asymmetry to lift the degeneracy of optical vortices

Abstract

We introduce an asymmetry in the core of a high charge optical vortex by using an appropriate computer generated hologram. The splitting of a high charge optical vortex core into unit charge vortices has been found to depend on the extent of the asymmetry. For a second order vortex, the trajectories of the split unit charged vortices and their separation have been recorded as a function of change in the asymmetry of the core. We find a good agreement between the experimentally obtained and numerically calculated results.

Far-field measurements of vortex beams interacting with nanoholes

“…However, instead of observing a vortex of charge l ′ = 3, three singularities of charge l = 1 are observed. This occurs because higher order phase singularities are very unstable and prone to split into first order singularities 52 53 54 55 . Thus, in the current scenario, a phase singularity of order l ′ will split into | l ′| singularities of order sign ( l ′).…”

Formation of optical vortices through superposition of two Gaussian beams

“…Equation (7) implies that when d z r θ at z 0, it forms a canonical optical vortex; otherwise it will be a noncanonical vortex. As the superposed structure propagates, the core becomes asymmetric, which results in an elliptical vortex beam [10]. It is also seen that the sign of vortices is decided by the sign of d and θ.…”

“…Nowadays spatial light modulators (SLMs) are more popular for generation of optical vortices. The forked grating [10] or the required phase pattern [11] can be transferred to the SLM to produce different order vortices. Recently, the vortices are also being produced with the help of integrated photonics [12].…”

Study of the birth of a vortex at Fraunhofer zone

“…In fact, it has been observed in other systems such as the breaking up of optical vortices [13,14]. Basically, in all these experimental and theoretical studies, some kind of asymmetry has been applied to a vortex.…”