Generation of Optical Vortices by Linear Phase Ramps

Sunil Vyas

doi:10.1155/2012/794259

Abstract

Generation of optical vortices using linear phase ramps is experimentally demonstrated. When two regions of a wavefront have opposite phase gradients then along the line of phase discontinuity vortices can be generated. It is shown that vortices can evolve during propagation even with the unequal magnitude of tilt in the two regions of the wavefront. The number of vortices and their location depend upon the magnitude of tilt. vortex generation is experimentally realized by encoding phase mask on spatial light modulator and their presence is detected interferometrically. Numerical simulation has been performed to calculate the diffracted intensity distribution from the phase mask, and presence of vortices in the diffracted field is detected by computational techniques.

Highlights

Optical fields possessing phase singularities or wavefront dislocations have received great deal of attention in recent years because of their fascinating properties and potential applications
In the neighborhood of the phase discontinuity line y = 0, if the x-components of the phase gradients are opposite in y > 0 and y < 0 regions, it is possible to generate vortices. β1 and β2 are constants
In [11] the phase gradients in the upper and lower parts of the beam point are in opposite directions

Summary

Introduction

Optical fields possessing phase singularities or wavefront dislocations have received great deal of attention in recent years because of their fascinating properties and potential applications. The study of phenomena associated with phase singularities has generated a new branch of physical optics called singular optics, which reveals their basic properties and possible applications. Phase singularities known as optical vortices are the points where the real and imaginary part of wave function vanishes. Nye and Berry showed that vortices in scalar field are strongly connected with the phase discontinuities or singularities [1]. In recent years several important applications of optical vortices have been demonstrated. For example vortices have been used in optical tweezers [7], wave guiding [8], astronomy as coronagraph [9], optical testing [10], and so forth

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