High-angle diffraction of a Gaussian beam by the grating with embedded phase singularity

TL;DR

This paper investigates how Gaussian beams diffracted by a specialized grating with embedded phase singularity produce complex optical vortex patterns, including high-order vortex decomposition and intensity profile rotation, without small-angle constraints.

Contribution

It provides a theoretical and numerical analysis of high-angle diffraction effects on optical vortex beams created by a grating with groove bifurcation, expanding understanding beyond previous small-angle assumptions.

Findings

High-order OV decomposition into secondary single-charged OVs.

Intensity profile rotation during diffraction.

Conditions for maximum separation of secondary OVs.

Abstract

Spatial characteristics of the optical-vortex (OV) beams created during the Gaussian beam diffraction by a grating with groove bifurcation are analyzed theoretically and numerically. In contrast to previous works, condition of small-angle diffraction is no longer required and the diffracted beam can be strongly deformed. This causes the intensity profile rotation and the high-order OV decomposition into a set of secondary single-charged OVs. These effects are studied quantitatively and confronted with similar properties of a Laguerre-Gaussian beam that undergoes astigmatic telescopic transformation. In contrast to the latter case, the secondary OVs do not lie on a single straight line within the beam cross section, and morphology parameters of the individual secondary OVs carried by the same beam are, in general, different. Conditions for maximum relative separation of the secondary OVs with respect to the beam transverse size are specified. The results can be used for practical generation of OV beams and OV arrays with prescribed properties.