Young’s experiment with waves near zeros

Abstract

We report an interesting observation in the formation of Young's fringes from a two pinhole arrangement illuminated by waves from the neighborhood of a zero of an optical phase singularity. Spacing of the Young's fringes appears to defy the dependence of pin-hole separation. But for larger pinhole separation such an anomalous phenomenon is not discernible. The experiments show that the fringe spacing is governed by the stronger local phase gradient near the vortex core that also has a radial part. Many diffraction experiments reported so far have missed this aspect as the phase gradient in a vortex beam is normally considered to have only azimuthal and longitudinal components. This work reveals the vortex core structure and is the first experimental evidence to the existence of a radial component of this phase gradient.

Phase Singularities to Polarization Singularities

“…e phase distribution ϕ is given by azimuthally varying function mθ, where θ is the polar angle. e transverse phase gradient [18,[33][34][35] for this vortex is given by ∇ϕ � (m/r) 􏽢 θ. is phase gradient is mainly circulating, and near the vortex core, its magnitude is high [11,32,36] and it also has some radial component [37][38][39]. e phase contours of different phase values terminate at the vortex (singular point), resulting in phase ambiguity, and therefore, the amplitude is zero at the vortex core.…”

“…In scalar optical fields, the properties of phase singular beams came under study [31,36]. e topological properties of vortices are studied in detail [37][38][39][168][169][170][171][172][173].…”

“…e handedness and azimuthal energy flow in optical vortex beams is also reported [248]. e radial [38,169,249] components of the propagation vector in a vortex beam came under scrutiny of few groups. Several other theoretical [25,26,[250][251][252][253][254] and experimental [255][256][257][258][259][260] investigations exist for Poynting singularities in transverse energy flow.…”

“…Normally, a higher topological charge vortex is unstable [339] and disintegrates into unit charged vortices under perturbation. Diffraction by single [80,340], double [38,319,341], and multiple slits [320] was studied and used for vortex detection. Multiple slits correspond to grating, and special gratings were also designed [263,321,342] for the diffraction study.…”

Data Visualization Using Hodge Decomposition - A Short Review

“…It had been applied to polarized vector fields and to reconstruct phase for wavefront distortions. We used HHD on scalar optical fields and studied the Orbital angular momentum (OAM) in diffraction optics that has been reported [10][11][12][13][14][15].…”