Recovery and Characterization of Orbital Angular Momentum Modes with Ghost Diffraction Holography

Abstract

Orbital angular momentum (OAM) of optical vortex beams has been regarded as an independent physical dimension of light with predominant information-carrying potential. However, the presence of scattering environment and turbulent atmosphere scrambles the helical wavefront and destroys the orthogonality of modes in vortex beam propagation. Here, we propose and experimentally demonstrate a new basis for the recovery of the OAM mode using a holographic ghost diffraction scheme. The technique utilizes the speckle field generated from a rotating diffuser for optical vortex mode encoding, and the fourth-order correlation of the speckle field for the efficient recovery of the associated modes. Furthermore, we successfully demonstrate the complex-field recovery of OAM modes by the adoption of a holography scheme in combination with the ghost diffraction system. We evaluate the feasibility of the approach by simulation and followed by experimental demonstration for the recovery of various sequentially encoded OAM modes. Finally, the efficacy of the recovered modes was quantitatively analyzed by an OAM mode analysis utilizing orthogonal projection scheme.

Ghost Diffraction Holography: A Correlation Assisted Quantitative Tool for Complex Field Imaging and Characterization

“…The development of unconventional correlation assisted GDH design capable of simultaneous detection of ghost diffraction intensity distribution by synchronizing Quantitative comparison of experimental and simulation results of various OAM modes recovered using GDH system: (a) variation of inner and outer radii with the topological charge (r1, inner radius and r2, outer radius); (b) variation of area of dark core (Ad, dark core) and area of bright annular ring (Ar, annular ring) of the recovered OAM modes. Adapted from [50].…”

“…The characteristic feature of the complex correlation function recovery of GDH system is recently exploited to develop a technique for the recovery and characterization of OAM modes [50]. The OAM associated with a vortex electromagnetic wave is an independent physical dimension of light having the characteristics of orthogonality and infinite-dimensional basis, which have remarkable applications in imaging, optical communication, quantum and classical information processing, multidimensional coding, etc.…”

“…Schematic of the experimental design of the GDH system for the generation and recovery of OAM modes; He-Ne: helium-neon laser source; M: mirror; SF: spatial filter assembly; L: lens; HWP: half wave plate; A: aperture; GG: ground glass diffuser; BS: beam splitter; SLM: spatial light modulator; MO: microscope objective; and CCD: charge coupled device camera. Adapted from [50].…”

“…Experimental results: (a-d) retrieved correlation holograms; (e-h) recovered amplitude distributions of the OAM modes; and(i-l) recovered phase distributions of the OAM modes; scale bar: 110 μm. Adapted from[50].…”

Wavefront phase calculation of optical vector beams using phase shifting interferometry

“…This is advantageous since any defect in the generation of phase distribution can be directly visualized on the phase pattern. Examples include the use of a phase-only SLM as a phase-shifting element within a Mach-Zehnder interferometer [25] or with ghost diffraction holography [26]. In this paper, we present a different method based on phase shifting technique to directly obtain the phase distribution of superposition of LG beams and so the topological charge can be obtained.…”