Shaping Laguerre-Gaussian laser modes with binary gratings using a Digital Micromirror Device

TL;DR

This paper presents a holographic method to generate high-purity Laguerre-Gaussian laser modes using a binary amplitude DMD, offering a cost-effective and high-speed alternative to phase-only modulators.

Contribution

It introduces a novel holographic technique for creating pure LG modes with a binary amplitude DMD, demonstrating high purity and self-similarity of the shaped beams.

Findings

Beam purity exceeds 94%

Shaped beams exhibit self-similarity

Phase fronts are helical as required

Abstract

Laguerre-Gaussian (LG) beams are used in many research fields, such as microscopy, laser cavity modes and optical tweezing. We develop a holographic method of generating pure LG modes (amplitude and phase) with a binary amplitude-only Digital Micromirror Device (DMD), as an alternative to the commonly used phase-only Spatial Light Modulator. The advantages of such a DMD include very high frame rates, low cost and high damage thresholds. We show that the propagating shaped beams are self-similar and their phase fronts are of helical shape as demanded. We estimate the purity of the resultant beams to be above 94%.