Experimental observation of anisotropic diffraction induced by orbital angular momentum

TL;DR

This paper experimentally demonstrates that orbital angular momentum (OAM) induces anisotropic diffraction in optical beams, revealing new phenomena like spiraling elliptic beams and stable elliptic solitons in isotropic media.

Contribution

It provides the first direct experimental evidence linking OAM to anisotropic diffraction and observes novel spiraling elliptic beams and solitons in isotropic media.

Findings

Observation of spiraling elliptic Gaussian beams at critical OAM in free space

Stable propagation of elliptic solitons in lead glass with OAM

Power-controlled rotation of elliptic beams

Abstract

We reveal for the first time a direct relationship between the diffraction of optical beams and their carrying orbital angular momentum (OAM). We experimentally demonstrate a novel phenomenon that the anisotropic diffraction can be induced by the OAM, predicted by us [Opt. Express, \textbf{26}, 8084 (2018)], via the propagations of the elliptic beams with the OAM in linearly and both-linearly-and-nonlinearly isotropic media, respectively. In the former case, when its carrying OAM equals the so-called critical OAM, the spiraling elliptic Gaussian beam (fundamental eigenmode) is observed in the free space, where only the eigenmode with cylindrical-symmetry is supposed to exist for the beam without the OAM. In the latter case, the spiraling elliptic soliton, predicted by Desyatnikov et al. [Phys. Rev. Lett, \textbf{104}, 053902 (2010)], is observed to stably propagate in a cylindrical lead glass. The power-controllable rotation of such an elliptic beam is also experimentally demonstrated.