Structured light in atmospheric turbulence—a guide to its digital implementation: tutorial

Structured light has gained prominence of late, offering a modern toolkit for controlling all of light’s degrees of freedom and facilitating many applications. A highly topical application is the long distance free-space delivery of structured light, essential in classical and quantum communication, remote sensing, and energy transport. Unfortunately atmospheric turbulence tends to distort the structure of light, negating many of the benefits. For this reason, laboratory studies of structured light in simulated atmospheric turbulence are highly desirable in order to study and mitigate these deleterious effects. Here, we outline how to get started with simulating atmospheric turbulence in the laboratory, from single-phase-screen approximations of weak turbulence to experimentally simulating long path strong turbulent conditions. Core to our approach is the use of modern digital tools in the form of digital micro-mirror devices and liquid crystal spatial light modulators, allowing fast, efficient, and realistic conditions to be realized in the laboratory. We show how to create and pass structured light through the simulated medium and outline the toolkit available for fast probing of the medium. We highlight all the potential pitfalls and common errors in this topical field, providing the code to circumvent them for immediate implementation. Finally, we show how the tutorial can be extended to the quantum regime, as well as general studies of complex light in complex media. This tutorial will be beneficial to both a beginner audience wishing to get started, as well as experienced researchers who wish to unravel the nuances of this approach.