Direct phase mapping of broadband Laguerre-Gaussian metasurfaces

TL;DR

This paper demonstrates the design and fabrication of broadband metasurfaces that generate Laguerre-Gaussian beams with precise phase control, using nanoantenna arrays to encode helical phase profiles for advanced optical applications.

Contribution

The work introduces a novel broadband metasurface approach for direct phase mapping of Laguerre-Gaussian modes using nanoantenna orientation encoding.

Findings

Broadband operation of metasurfaces confirmed across different laser sources.

Successful encoding of helical phase profiles with radial discontinuities.

Accurate measurement of orbital angular momentum using interferometry and holography.

Abstract

We report on the fabrication of metasurface phase plates consisting of gold nanoantenna arrays that generate Laguerre-Gaussian modes from a circularly polarized Gaussian input beam. The corresponding helical phase profiles with radial discontinuities are encoded in the metasurfaces by the orientation of the nanoantennas. A common-path interferometer is used to determine the orbital angular momentum of the generated beams. Additionally, we employ digital holography to record detailed phase profiles of the Laguerre-Gaussian modes. Experiments with different laser sources demonstrate the broadband operation of the metasurfaces.