Unscrambling OAM mode using digital phase-shifting in the Stokes fluctuations correlation

Abstract

In this Letter, we propose and experimentally demonstrate a new, to the best of our knowledge, non-interferometric and highly stable technique to unscramble the incident orbital angular momentum (OAM) state and quantitatively measure the phase structure from the non-imaged random light. A new theoretical basis is developed and also verified by numerical simulation and experimental demonstration. We also quantitatively investigate the OAM modes of the incident light using orthogonal projection.

Phase shifting to measure the modal composition of the scattered helical beam

“…The use of a QWP in the experimental set-up is highly sensitive and affects the state of polarization measurements [44]. A digital four-step phase-shifting approach with Stokes correlation was also developed to retrieve the phase profile of the IVB [45].…”

Stokes correlation to estimate topological charge from the speckle pattern

“…The information-bearing properties of the speckle patterns were explored to develop different detection schemes for the recovery of incident helical beams. Researchers have used coherent light to generate speckle patterns and utilized information-bearing properties of this pattern to develop detection techniques for the recovery and estimation of TC of the helical beam [19][20][21][22][23][24][25] and in the examination of polarization properties [26]. In a recent development, the Hanbury-Brown Twiss effect was combined with off-axis holography to estimate the TC of the helical beam.…”