Superpixel-based spatial amplitude and phase modulation using a digital micromirror device

TL;DR

This paper introduces a superpixel method for precise control of light's phase and amplitude using a DMD, achieving high fidelity and reducing errors compared to existing holography techniques.

Contribution

The authors develop a superpixel approach that enables independent phase and amplitude modulation with high fidelity and speed, improving upon previous holography methods.

Findings

Achieves a fidelity of 0.98 for independent phase and amplitude control at 8x8 resolution.

Fidelity of 0.99993 for LG10 orbital angular momentum mode at high resolution.

Reduces errors by 50% and 18% compared to Lee holography, with similar light efficiency.

Abstract

We present a superpixel method for full spatial phase and amplitude control of a light beam using a digital micromirror device (DMD) combined with a spatial filter. We combine square regions of nearby micromirrors into superpixels by low pass filtering in a Fourier plane of the DMD. At each superpixel we are able to independently modulate the phase and the amplitude of light, while retaining a high resolution and the very high speed of a DMD. The method achieves a measured fidelity $F=0.98$ for a target field with fully independent phase and amplitude at a resolution of $8\times 8$ pixels per diffraction limited spot. For the LG$_{10}$ orbital angular momentum mode the calculated fidelity is $F=0.99993$, using $768\times 768$ DMD pixels. The superpixel method reduces the errors when compared to the state of the art Lee holography method for these test fields by $50\%$ and $18\%$, with a comparable light efficiency of around $5\%$. Our control software is publicly available.