Control of optical vortex dislocations using optical methods

Abstract

In this paper we present the results of theoretical and experimental investigations of the optical vortex screw-dislocation position control based on optical vortex interference with the Gaussian beam. Optical vortices can be controlled by joining a Gaussian beam with a collinear optical vortex beam and changing the Gaussian beam intensity and phase. It is shown theoretically and experimentally that in this way it is possible to precisely change the optical vortex screw-dislocation position in plane transverse to propagation direction.

Topological charge transformation of beams with embedded fractional phase step in the process of second harmonic generation

“…On the contrary, the regular part does not have a vortex structure, therefore, its dark core will vanish upon propagation and, in the far field, the Poisson spot will be observed. Similarly to that described in [4,6], where the unit-charged optical vortex is superimposed with a coherent background beam, the structure of the beam will result in an off-axis unit-charged optical vortex.…”

“…The winding of the helical wavefront is described by a parameter known as the topological charge or the strength of a phase singularity, which we will denote by l. The topological charge describes the direction and multiplicity of the helical wavefront [4,5]. Although, theoretically, dislocations could have any topological charge, it was shown that, in the presence of coherent background, only dislocations of topological charge =  l 1 are stable and retain their properties upon linear propagation [4,6].…”