Polarized vortices in optical speckle field: observation of rare polarization singularities.

Jan Dupont,Xavier Orlik

doi:10.1364/oe.23.006041

Abstract

Using a recent method able to characterize the polarimetry of a random field with high polarimetric and spatial accuracy even near places of destructive interference, we study polarized optical vortices at a scale below the transverse correlation width of a speckle field. We perform high accuracy polarimetric measurements of known singularities described with an half-integer topological index and we study rare integer index singularities which have, to our knowledge, never been observed in a speckle field.

Highlights

Wave dislocations [1], and the associated phase singularities, are notions which come with diffraction
Using a recent method able to characterize the polarimetry of a random field with high polarimetric and spatial accuracy even near places of destructive interference, we study polarized optical vortices at a scale below the transverse correlation width of a speckle field
We perform high accuracy polarimetric measurements of known singularities described with an half-integer topological index and we study rare integer index singularities which have, to our knowledge, never been observed in a speckle field

Summary

Introduction

Wave dislocations [1], and the associated phase singularities, are notions which come with diffraction. In order to carry out the polarimetric analysis of polarization singularities in such a field, we use a new method [10] sufficiently sensitive to perform polarimetric measurements near places where wave dislocations occur, i.e. where the intensity vanishes. Some types of polarization singularities called star, lemon, monstar have been widely studied [11,12,13,14,15,16], and are described with an half integer index. We point out here high accuracy measurements of these three known types of half integer index singularities in a speckle field. We detect other polarimetric structures which exhibit an integer index Their geometric shapes have already been observed [16] and simulated [17] in maps of instantaneous direction of the transverse electric field, at places where half integer index polarization singularities occur. We detect in a speckle field polarimetric ellipse arrangement along these geometric shapes

Polarimetric analysis by full projection in the Poincarespace

Optical vortices and classification of polarization singularities

Experimental results

Conclusion